Wireless communication system, wireless communication method, and wireless communication program

Abstract

To achieve stable command communication from a ground station to a terminal station.SOLUTION: A terminal station 01 includes an interference wave detection unit 105 that detects a signal band in which an interference wave exists from a received spectrum as interference wave detection information. The terminal station 01 also includes a communication method determination unit 106 that determines center frequencies of command signals for N channels (N is a natural number) based on the interference wave detection information and SINRs measured by N demodulation units. In addition, N demodulation units 108 wait for command signals for the respective center frequencies for the N channels and demodulate the command signals. A combination unit 109 combines the N command signals. A telemetry transmission unit 110 transmits the center frequencies for the N channels to a ground station 04 as a telemetry signal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a wireless communication system, a wireless communication method, and a wireless communication program for wirelessly transmitting command signals for controlling a terminal station from a ground station to a terminal station, such as an artificial satellite or an unmanned aerial vehicle. [Background technology]

[0002] When transmitting command signals wirelessly from a ground station to a terminal station, interference from other systems may prevent the commands from being correctly received by the terminal station, making it impossible for the ground station to remotely control the terminal station.

[0003] As a countermeasure, for example, in Non-Patent Document 1, in a satellite communication system using a spread spectrum communication method that is resistant to interference, an interference suppression function is implemented in the receiver (transponder) of the terminal station. Non-Patent Document 1 shows that if the bandwidth (A [Hz]) of the interference wave is sufficiently narrow (A << B) compared to the bandwidth (B [Hz]) of the spread spectrum command signal, good communication quality can be maintained due to the interference suppression effect. In this case, not only the interference wave component but also a part of the command signal component is suppressed, but since the suppressed bandwidth is A / B of the entire command signal, if A is sufficiently small compared to B (A / B << 1), the impact of suppressing the command signal component is slight. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] “Adaptive Interference Rejection Filtering in On-Board Direct-Sequence / Spread-Spectrum Transponder for TT&C Applications: Analysis, Simulation & Breadboard Test Results”, L. Simone, F. Caselli, 2008 NASA / ESA Conference on Adaptive Hardware and Systems, IEEE, Aug. 2008. Summary of the Invention [Problem to be solved by the invention]

[0005] When the interference wave becomes wideband and the bandwidth of the interference wave becomes equal to or larger than the bandwidth of the spectrum-spread command signal (A≧B), the technology of Non-Patent Document 1 cannot be used. When the interference wave becomes wideband, not only the interference wave components but also the frequency components of the command signal are all suppressed, resulting in the terminal station being unable to correctly receive commands from the ground station. In this case, it is effective to use a means for changing the center frequency of the received command signal to a frequency band where no interference wave exists. However, because the frequency switching command from the ground station cannot be received due to the effects of interference waves, the frequency cannot be switched and the terminal station cannot escape from an uncontrollable state.

[0006] The present disclosure aims to achieve stable command communication even when interference waves are scattered over a wide band or the frequency of interference waves fluctuates, by having a terminal station observe the uplink reception spectrum, and based on the observation results and the reception state of the demodulator, determine an appropriate center frequency of a command signal and an appropriate modulation method, and notify the ground station of the determination result, and the ground station transmits commands based on the frequency and modulation method of the command signal determined by the terminal station. [Means for solving the problem]

[0007] A wireless communication system according to the present disclosure includes a terminal station and a ground station that transmits a command signal to the terminal station, and the terminal station transmits a telemetry signal to the ground station. The terminal station, a spectrum measurement unit that measures a power spectrum of a received signal as a received spectrum; an interference wave detection unit that detects a signal band in which an interference wave exists from the reception spectrum by using a threshold value as interference wave detection information; a communication method determination unit that determines a center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and SINR (signal power to interference plus noise power ratio) measured by N demodulation units; The N demodulation units wait for a command signal for each of the center frequencies of the N channels, and when a command signal is received, demodulate the command signal and transmit the SINR to the communication method determination unit; a synthesis unit that synthesizes the N command signals demodulated by the N demodulation units and outputs the synthesized signal as command data; and a telemetry transmitting unit that transmits the center frequencies for the N channels to the ground station as a telemetry signal. Effect of the Invention

[0008] In the wireless communication system according to the present disclosure, an appropriate command signal frequency and an appropriate modulation method are determined based on the reception spectrum measured by the terminal station and the reception state of the demodulator, and the ground station transmits commands at the command signal frequency and modulation method determined by the terminal station. This has the effect of maintaining a high reception SINR regardless of the bandwidth or frequency of the interference wave, thereby achieving uninterrupted, stable command communication. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a wireless communication system according to a first embodiment. [Diagram 2]FIG. 2 is a diagram showing a configuration example of a terminal station according to the first embodiment; [Diagram 3] FIG. 2 is a diagram showing a configuration example of a ground station according to the first embodiment. [Figure 4] 4 is a flowchart showing an operation related to a command line in the wireless communication system according to the first embodiment. [Diagram 5] FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result (at the time of initial observation) according to the first embodiment. [Figure 6] FIG. 2 is a diagram showing an example of a modulation method that can be selected by a communication method determination unit according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing an example of uplink frequency and modulation scheme determination in a communication scheme determination unit according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing an example of interference suppression amount information corresponding to FIG. 7; [Figure 9] FIG. 2 is a diagram showing an example of the configuration of a spectrum measurement unit and an interference suppression unit according to the first embodiment. [Figure 10] 4 is a diagram showing timing control of Side A and Side B in the interference suppression unit according to the first embodiment. [Figure 11] FIG. 11 is a diagram showing the difference between a case where a delay process according to the first embodiment is performed and a case where the delay process is not performed. [Figure 12] FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result (after interference suppression) according to the first embodiment. [Figure 13] FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result according to the first embodiment (after transmitting a command signal). [Figure 14] 4 is a diagram showing a state in which a reception S / IN and a reception level are calculated when a command signal is demodulated in the first embodiment. FIG. [Figure 15] FIG. 13 is a diagram showing an example of an uplink signal spectrum observation result (after interference wave (a) changes) according to the first embodiment and an uplink frequency and modulation method designation for modulated wave #2. [Figure 16] FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result according to the first embodiment (after changing the frequency of modulated wave #2). [Figure 17]FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result according to the first embodiment and an uplink frequency and modulation method designation for each modulated wave. [Figure 18] FIG. 4 is a diagram showing an example of an uplink signal spectrum observation result according to the first embodiment. [Figure 19] FIG. 2 is a diagram showing an example of a hardware configuration of each device in the wireless communication system according to the first embodiment. [Figure 20] FIG. 13 is a diagram showing another example of the hardware configuration of each device in the wireless communication system according to the first embodiment. [Figure 21] FIG. 11 is a diagram showing an uplink signal spectrum observation result according to the second embodiment. [Figure 22] FIG. 13 is a diagram showing a configuration example of a ground station according to a third embodiment. [Figure 23] FIG. 11 is a diagram showing a configuration example of a terminal station according to the third embodiment. [Figure 24] FIG. 13 is a diagram showing an example of the configuration of a wireless communication system according to a fourth embodiment. [Diagram 25] FIG. 13 is a diagram showing a configuration example of a terminal station according to the fourth embodiment. [Figure 26] FIG. 13 is a diagram showing a configuration example of a ground station according to a fourth embodiment. [Figure 27] FIG. 11 is a flow diagram showing an operation related to a telemetry line in the wireless communication system according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment will be described with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals. In the description of the embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate. The arrows in the drawing mainly indicate the flow of data or the flow of processing. In addition, the relationship of the size of each component in the following drawings may differ from the actual one. In addition, in the description of the embodiment, directions or positions such as up, down, left, right, front, back, front, and back may be indicated. These notations are for convenience of explanation and do not limit the arrangement, direction, or orientation of devices, instruments, parts, etc.

[0011] Embodiment 1 ***Configuration Description*** FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 500 according to the present embodiment. In FIG. 1, a wireless communication system 500 includes a terminal station 01 , a ground station 04 , and an interference source 09 . The terminal station 01 is equipped with a receiving antenna 02 and a transmitting antenna 03 . The ground station 04 is equipped with a receiving antenna 05 and a transmitting antenna 06 . A telemetry signal 08 is transmitted from a transmitting antenna 03 of the terminal station 01 to a receiving antenna 05 of a ground station 04. In addition, a command signal 07 is transmitted from a transmitting antenna 06 of the ground station 04 to a receiving antenna 02 of the terminal station 01. An interference wave 10 is transmitted from an interference source 09 .

[0012] FIG. 2 is a diagram showing an example of the configuration of the terminal station 01 according to the present embodiment. The terminal station 01 includes an amplifier 99, a receiving filter 100, a variable gain unit 101, an automatic gain control unit 102, an AD converter 103, a spectrum measurement unit 104, an interference wave detection unit 105, a communication method determination unit 106, an interference suppression unit 107, a demodulation unit 108, a synthesis unit 109, and a telemetry transmission unit 110. AD is an abbreviation for Analog Digital. The demodulation unit 108 includes a demodulation unit #1_108a, a demodulation unit #2_108b, and a demodulation unit #3_108c.

[0013] FIG. 3 is a diagram showing an example of the configuration of the ground station 04 according to this embodiment. The ground station 04 includes a telemetry receiving unit 200, a data duplicating unit 201, a modulating unit 202, and a combining unit 203. The modulating unit 202 includes a modulating unit #1_202a, a modulating unit #2_202b, and a modulating unit #3_202c.

[0014] ***Explanation of Operation*** FIG. 4 is a flow diagram showing operation related to a command line in wireless communication system 500 according to the present embodiment. 4 shows an operation flow regarding the command line in the wireless communication system 500. In this figure, step S3 is a process performed by the ground station 04. The other steps, step S1, step S2, and step S4 to step S6, are processes performed by the terminal station 01.

[0015] The operation of wireless communication system 500 according to the present embodiment will be described. 1, a wireless communication system 500 according to this embodiment is composed of a ground station 04 and a terminal station 01. The ground station 04 transmits a command signal to the terminal station 01, and the terminal station 01 transmits a telemetry signal to the ground station 04. In the wireless communication system 500 according to this embodiment, even when an interference wave 10 from an interference source 09 is input to the terminal station 01, stable command communication is realized without being affected by the interference wave 10. Here, the command signal is a radio signal modulated with command information for remotely operating the terminal station 01 from the ground station 04. In the following, the upward link from the ground station 04 to the terminal station 01 is called an uplink, and the downward link from the terminal station 01 to the ground station 04 is called a downlink.

[0016] <Step S1: Uplink signal spectrum observation (before receiving command signal)> First, the terminal station 01 receives an uplink signal using the receiving antenna 02 shown in FIG. 2, and after the power of the received signal is amplified by an amplifier 99, a receiving filter 100 filters out only the frequency components of the system band assigned to the wireless communication system. Next, terminal station 01 automatically controls the reception level using variable gain section 101 and automatic gain control section 102 so that the level of the filtered reception signal falls within the input dynamic range of downstream AD converter 103. The gain value of variable gain section 101 is controlled by automatic gain control section 102. Automatic gain control section 102 controls the reception signal level input to downstream AD converter 103 to be below a certain level, thereby preventing saturation of AD converter 103 even when terminal station 01 receives a high-level command signal or a high-level interference wave.

[0017] The spectrum measurement unit 104 measures the power spectrum of the received signal as the received spectrum. More specifically, this is done as follows. The spectrum measurement unit 104 in Fig. 2 converts the received data sequence (= data sequence in the time domain) output from the AD converter 103 into a data sequence in the frequency domain. The means for converting to the frequency domain uses a fast Fourier transform (FFT) or a discrete Fourier transform (DFT), etc. The data converted to the frequency domain is squared for each frequency bin and converted into a power value to obtain the power spectrum of the received signal. If a more accurate power spectrum is required, multiple power spectra are averaged for each frequency bin. This power spectrum is the received spectrum of the uplink frequency band assigned to the system itself. An example of the configuration will be described later with reference to Fig. 9.

[0018] Through such signal processing, the terminal station 01 performs the initial operation "Step S1: Uplink signal spectrum observation" shown in Fig. 4. At this point, a command signal has not yet been transmitted from the ground station 04. Furthermore, this spectrum observation operation does not have to be started by a command from the ground station 04, but may be started when the terminal station 01 is manually powered on, or after a certain period of time has elapsed after powering on using a timer. In this way, by not issuing a command to start the operation by a command from the ground station 04, the effects of interference waves can be avoided.

[0019] FIG. 5 is a diagram showing an example of an uplink signal spectrum observation result (at the time of initial observation) according to the present embodiment. FIG. 5 shows the initial operation, and thus the ground station 04 has not yet transmitted a command signal to the terminal station 01. The horizontal axis represents frequency, and only the frequency bands allocated to the wireless communication system 500 are shown. As shown in Figure 5, interference waves from interference source 09 are observed as (a), (b), and (c). Interference waves (a) and (c) exist statically in the frequency band shown in Figure 5. Interference wave (b), which is made up of three narrowband interference waves, shows how the center frequencies of each wave change dynamically within the range indicated by the dotted arrows in Figure 5.

[0020] The terminal station 01 needs to detect such dynamic changes in interference waves. Therefore, the spectrum measurement unit 104 observes the uplink signal spectrum not just once, but repeatedly, and sequentially transmits the observed results to the interference wave detection unit 105 at the downstream.

[0021] <Step S2: Determining the uplink communication method (before receiving a command signal)> <<Determination of threshold value TH and detection of interference wave>> Next, the interference wave detection unit 105 detects a signal band in which an interference wave exists from the received spectrum, as interference wave detection information, using a threshold value. The interference wave detection unit 105 detects the presence or absence of an interference wave by comparing the uplink signal spectrum observation result from the spectrum measurement unit 104 with the threshold value TH shown in Fig. 5. This detection operation is repeatedly performed every time the uplink signal spectrum observation result is sent from the spectrum measurement unit 104. This threshold value TH is used in the initial stage when no command signal has been received from the ground station 04. After receiving a command signal from the ground station 04, the threshold value is changed to another threshold value THR(i) (where i∈{0, 1, . . . N-1}) described later. Here, the threshold value TH is provided by the communication method determination unit 106, but since at this point in time the command signal from the ground station 04 has not yet been received, the received power of the command signal is not used in calculating the threshold value TH.

[0022] The communication method determination unit 106 determines the threshold value by using noise power information measured in advance before operation. Specifically, the process is as follows. The communication method determination unit 106 determines the threshold value TH based on the noise level generated in the amplifier 99 etc. of the terminal station 01, the control value ATT [dB] given to the variable gain unit 101 by the automatic gain control unit 102, and the relative threshold value ΔTH [dB]. Specifically, if the noise power at ATT=0 dB in the frequency bin band during the FFT (or DFT) is NZ [dBm / bin] and the relative threshold value is ΔTH [dB], then TH [dBm / bin] is calculated by the following (Equation 1). The relative threshold value ΔTH [dB] is the actual adjustment parameter.

[0023] TH[dBm / bin]=NZ[dBm / bin]+ΔTH[dB]-ATT[dB] Equation (1)

[0024] Note that ATT is attenuated when it is positive. For example, when ATT=3, the received power is attenuated by -3dB. NZ [dBm / bin] is given as a known value from the test data obtained during the development stage before operation. In this way, the communication method determination unit 106 obtains the threshold value TH [dBm / bin] from the formula (1) instead of from the power spectrum of the received signal. If the threshold value TH is obtained from the power spectrum of the received signal, the power spectrum is disturbed by the appearance or disappearance of an interference wave, and the threshold value TH is also affected and varies in value. On the other hand, in this embodiment, as shown in formula (1), the noise power NZ [dBm / bin] is a known value obtained from measurement data obtained at the development stage before operation. Therefore, the noise power NZ [dBm / bin] does not vary due to the appearance or disappearance of an interference wave. Therefore, the threshold value TH [dBm / bin] obtained from formula (1) is prevented from being affected by the appearance or disappearance of an interference wave. The only case where ATT increases due to the appearance of interference is when the noise components added to the interference are also attenuated, so the threshold TH [dBm / bin] must be lowered by the amount attenuated by the ATT. In this case, the value of TH [dBm / bin] will fluctuate depending on the appearance or disappearance of the interference. However, as shown in equation (1), ATT is given as a constant value for all frequency bins, so TH [dBm / bin] does not become unstable for each frequency bin.

[0025] Here, if the threshold value TH is too low, the noise exceeds the threshold value TH, increasing the probability of being erroneously detected as an interference wave. On the other hand, if the threshold value TH is too high, the interference wave level falls below the threshold value TH, increasing the probability of not detecting the interference wave. Therefore, the communication method determination unit 106 sets the threshold value (TH) to an appropriate value so as to suppress both erroneous detection and non-detection. Furthermore, if the noise level changes depending on the temperature, the communication method determination unit 106 controls the threshold value TH so that it is an appropriate value for each temperature based on temperature information.

[0026] <<Determining the center frequency and modulation method of the command signal>> The communication method determination unit 106 determines the center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and the SINR (signal power to interference plus noise power ratio) measured by the N demodulation units. In addition to determining the center frequencies for the N channels, the communication method determination unit 106 also determines the modulation method of the command signal for each of the N channels from M types (where M∈{2, 3, ..}). The N demodulation sections wait for a command signal for each of the center frequencies for the N channels, and upon receiving a command signal, demodulates the command signal and simultaneously transmits the SINR to the communication method determination section 106 .

[0027] The communication method determination unit 106 determines the center frequency and modulation method of the command signal to be transmitted by the ground station 04 based on the interference wave detection information from the interference wave detection unit 105 and the demodulation states from demodulation unit #1 (108a), demodulation unit #2 (108b), and demodulation unit #3 (108c). The power spectrum measured by the spectrum measurement unit 104 is also transmitted to the communication method determination unit 106 via the interference wave detection unit 105. The power spectrum measured by the spectrum measurement unit 104 is used in the calculation of the SINR performed by the communication method determination unit 106. The specific calculation of the SINR will be described later.

[0028] In this embodiment, three demodulators are provided, and the ground station 04 copies the command data into three and then transmits the same data three times at the same time. That is, this is a configuration example in which the number N of parallel transmission channels for command signals is 3 (N=3). However, this is just one example, and N can be any number as long as it is 1 or more. Immediately after the initial operation, the ground station 04 is at a stage where it has not yet transmitted a command signal to the terminal station 01. Therefore, the demodulation status of the three demodulation units (108a, 108b, 108c) that demodulate the command signal on the terminal station 01 side is "waiting for command signal."

[0029] FIG. 6 is a diagram showing an example of modulation methods that can be selected by the communication method determining unit 106 according to this embodiment. The modulation schemes that the communication method determination unit 106 can select are two, direct spread spectrum (DSS) modulation and narrowband BPSK modulation, as shown in Fig. 6. DSS is an abbreviation for Direct Spread Spectrum. BPSK is an abbreviation for Binary Phase Shift Keying. Both modulation methods have the same data rate (R [bit / s]), and DSS modulation is achieved by first modulating a BPSK-modulated signal, then further spreading the signal with a spreading code of chip rate Y [chip / s] (Y≫R). Note that BPSK is just an example, and any modulation method such as FSK or QPSK may be used as long as it is a narrow-band modulation wave. In this embodiment, BPSK will be described as an example. FSK is an abbreviation for frequency shift keying. QPSK is an abbreviation for quaternary phase shift keying. In this way, the number of channels N may be 2 or more, and the modulation method may include a direct sequence spread spectrum (DSS) and a narrowband modulation method. The terminal station may transmit a spectrum of the narrowband modulation method and a spectrum of the direct sequence spread spectrum (DSS) in a state where they are overlapped on the frequency axis.

[0030] FIG. 7 is a diagram showing an example of the uplink frequency and modulation scheme determination in the communication scheme determining section 106 according to this embodiment. FIG. 8 is a diagram showing an example of interference suppression amount information corresponding to FIG.

[0031] The communication method determination unit 106 determines the center frequencies (F1, F2, F3) of the three command signals and their respective modulation methods {DSS, BPSK} as shown by 301, 302, 303 in FIG. 7, 301 denotes the modulation method (DSS) and center frequency (F1) for the modulation unit #1 (202a) of the ground station 04 specified by the communication method determination unit 106. 302 denotes the modulation method (BPSK) and center frequency (F2) for the modulation unit #2 (202b) of the ground station 04 specified by the communication method determination unit 106. 303 denotes the modulation method (BPSK) and center frequency (F3) for the modulation unit #3 (202c) of the ground station 04 specified by the communication method determination unit 106.

[0032] The signal processing steps up to when the communication method determination unit 106 determines each center frequency and each modulation method will be described below. Candidates for each center frequency and each modulation method designated by the communication method determination unit 106 are as follows. In the frequency range of the system band shown in Fig. 7, when a specific center frequency (FC) is assigned a specific modulation method (Mod Type), if the SINR calculated indicates a certain threshold value STH or more, the specific center frequency and the specific modulation method become candidates. In other words, when SINR ≥ STH, the specific center frequency and the specific modulation method become candidates for each center frequency and each modulation method designated by the communication method determination unit 106. SINR is an abbreviation for Signal to Interference & Noise Ratio. Here, STH is the required SINR required to achieve a certain bit error rate (BER) or less. Note that the value of STH varies depending on the modulation method of each command signal. For example, STH is high when the modulation method is multi-level modulation (16QAM, etc.) and low when the modulation method is BPSK. Furthermore, if the reception level of the command signal is S [dBm], the power of the interference wave is I [dBm], and the noise power is N [dBm], the SINR is calculated using the following equation (2).

[0033] SINR[dB]=S[dBm]-I[dBm]-N[dBm] Equation (2)

[0034] The bandwidth required to calculate the interference power (I) and noise power (N) is the same as the bandwidth of the command signal (=B), and the specific frequency range is the command signal center frequency F±0.5*B. The communication method determination unit 106 obtains N [dBm] shown in equation (2) as follows. When the bandwidth per bin after FFT or DFT is BF and the bandwidth of the command signal is B, the communication method determination unit 106 multiplies the noise power NZ [dBm / bin] by 10*log 10 It is calculated by adding (B / BF) [dB]. That is, it is as follows. N[dBm]=NZ[dBm / bin]+10*log 10 (B / BF) [dB]

[0035] Next, a specific method for calculating the interference wave component I [dBm] will be described. The communication method determination unit 106 calculates the total power SP [dBm] of the command signal in the frequency range F±0.5*B from the power spectrum measured by the spectrum measurement unit 104. If no interference wave exists in the frequency range F±0.5*B, the relationship SP [dBm] + ATT [dB] ≈ N [dBm] is established. Here, ATT [dB] is a control value that the automatic gain control unit 102 gives to the variable gain unit 101, and by adding this ATT value to SP, the condition is aligned with N [dBm], which is the value when ATT = 0 dB. On the other hand, if the relationship is SP [dBm] + ATT [dB] > N [dBm], it means that the interference wave component is included in {SP [dBm] + ATT [dB]}. Therefore, since the interference component is found from the difference between the antilogarithm of both, the communication method determining unit 106 calculates the interference wave component I [dBm] based on the following formula (2a).

[0036] I[dBm]=10*log 10 (10^((SP+ATT) / 10)-10^(N / 10)) Equation (2a)

[0037] On the other hand, the reception level S [dBm] of the command signal required to calculate the SINR in equation (2) is an expected value because it is an initial stage before the command signal is received. The expected value can be estimated from the communication distance D obtained from the position information of the terminal station 01 and the ground station 04, and the equivalent isotropically radiated power (EIRP) information of the ground station 04. EIRP is an abbreviation for Equivalent Isotropically Radiated Power. Note that when the terminal station 01 moves, the communication method determination unit 106 may obtain the position information of the terminal station 01 from the GPS. GPS is an abbreviation for Global Positioning System. Furthermore, since the noise components are mainly generated in the amplifier 99 within the terminal station 01, the noise power (N) required for calculating the SINR can be treated as a known value that is measured in advance during the terminal station manufacturing test. Through this calculation process, the terminal station 01 can calculate the SINR using the predicted value of the reception level S even before receiving the command signal.

[0038] In addition, when the modulation method is DSS, a spreading gain is obtained during demodulation, so the communication method determination unit 106 calculates the SINR after the spreading gain is obtained, as shown in the following formula (3). Spreading gain = 10 * log10 (Y / R) [dB].

[0039] SINR[dB]=S[dBm]-I[dBm]-N[dBm]+10*log10(Y / R)[dB] Formula (3)

[0040] Furthermore, in the case of DSS, only when the bandwidth (A [Hz]) of the interference wave is narrower than the bandwidth (B [Hz]) of the command signal, the SINR can be improved by suppressing only the frequency components mixed with the interference wave as described in the above non-patent document 1. For example, when only the frequency components mixed with the interference wave are suppressed to zero, the SINR is calculated by the following equation (4). By suppressing the interference wave, the interference wave power I does not exist in equation (4), and the interference wave is multiplied by the loss of the suppressed command signal power ((BA) / B).

[0041] SINR[dB]=S[dBm]-N[dBm]+10*log10(Y / R)[dB]+10*log10((BA) / B)[dB] Equation (4)

[0042] Therefore, when the modulation scheme is DSS, the communication method determination unit 106 calculates not only the SINR (equation 2) when interference is not suppressed, but also the SINR (equation 3) when interference is suppressed. Then, when the SINR when interference is suppressed is higher than the SINR when interference is not suppressed, the SINR when interference is suppressed is selected on the premise that interference is suppressed.

[0043] The communication method determination unit 106 performs the above SINR calculation while shifting the center frequency (FC) within the range of the system band, and records the results. The stored values ​​become the characteristics of frequency on the horizontal axis and SINR on the vertical axis. If there are multiple types of modulation methods, the SINR is calculated for each modulation method and the results are recorded. Furthermore, if the modulation method is DSS, the SINR when interference suppression is performed is also calculated and the results are recorded in the same manner.

[0044] In the process of performing the above-mentioned SINR calculation and comparison process with the threshold value STH, the communication method determination unit 106 detects the center frequency FC and the modulation method Mod Type at which the SINR is equal to or greater than the threshold value STH. In FIG. 7, the frequency band in which the interference wave (c) exists has a very high power density Io [dBm / Hz] of the interference wave (c), and the SINR does not exceed the threshold value STH in either BPSK or DSS. In this case, the communication method determination unit 106 avoids allocating the command signal to the frequency band in which the interference wave (c) exists, and proceeds to consider allocating the command signal to other frequency bands.

[0045] In the frequency band in which the interference wave (b) exists in Fig. 7, the center frequencies of the three narrowband interference signals change dynamically within the range of that frequency band. Furthermore, the level of each narrowband interference signal is strong enough that the SINR falls below the threshold value STH when it overlaps with the BPSK command signal. Therefore, it is not desirable to place BPSK in the frequency band in which the interference wave (b) exists. On the other hand, the total bandwidth of the three narrowband interference signals is sufficiently narrower than the signal bandwidth of DSS. If DSS is selected as the modulation method and the interference is suppressed, the SINR will be equal to or greater than the threshold value STH. In this case, the communication method determination unit 106 selects DSS as the modulation method for the modulation unit #1 (202a) of the ground station 04, and specifies its center frequency as F1 in the frequency band in which the interference wave (b) exists, as shown in FIG. At the same time, the communication method determination unit 106 issues a command to the interference suppression unit 107 to suppress the interference wave (b) consisting of three narrowband signals, based on the information detected by the interference wave detection unit 105. Specific information that the communication method determination unit 106 transmits to the interference suppression unit 107 is interference suppression amount information shown in FIG.

[0046] The communication method determining unit 106 repeats the above process every time the uplink signal spectrum observation result is output from the spectrum measuring unit 104 and the interference wave detection result is received from the interference wave detecting unit 105 . The interference suppression unit 107 suppresses the interference wave superimposed on the command signal based on reception level information of the interference wave detected by the interference wave detection unit 105, and provides the command signal after interference suppression to N demodulation units. The interference suppression unit 107 converts the received signal into the frequency domain, and then suppresses the interference wave (b) based on interference suppression amount information (FIG. 8) from the communication method determination unit 106.

[0047] FIG. 9 is a diagram showing an example of the configuration of spectrum measurement section 104 and interference suppression section 107 according to this embodiment. The interference suppression unit 107 and the spectrum measurement unit 104 will be described in detail with reference to FIG. In the configuration example of Fig. 9, FFT is used as a means for time-frequency conversion, and IFFT is used as a means for frequency-time conversion. Even when interference is suppressed for a received signal, a two-parallel configuration is used as shown by the dashed lines in Fig. 9 to maintain the continuity of the time waveform so that the time waveform is not partially lost during suppression. In Fig. 9, the two parallel configurations are Side A 409 and Side B 410. In order to maintain such continuity, the spectrum measurement unit 104 shifts the processing timing of Side B by N / 2 samples (where N is the number of FFT points) under timing control from the timing control unit 301.

[0048] FIG. 10 is a diagram showing timing control of Side A and Side B in interference suppression section 107 according to this embodiment. In Fig. 10, (A) shows the time waveform output from Hanning window adding unit 302 on the Side A side. Also, (B) shows the time waveform output from Hanning window adding unit 303 on the Side B side. As is clear from Fig. 10, the processing on the Side B side is shifted by N / 2 samples (where N is the number of FFT points) compared to the Side A side.

[0049] By applying such timing control to two parallel Hanning window processing, the original input time waveform is restored when both (A) and (B) are added. The NpointFFT unit 304 performs an FFT on the time waveform of N successive samples, such as (1), (3), and (5), shown in Fig. 10. Moreover, the NpointFFT unit 305 performs an FFT on the time waveform of N successive samples, such as (2), (4), and (6), shown in Fig. 10. Even if these two FFT-processed data series are not subjected to interference suppression, but are subjected to IFFT again to return them to the original time domain data series, and the two are added by the adder 408, the original input time waveform is restored.

[0050] Power conversion section 306 in spectrum measurement section 104 converts output data of Npoint FFT section 305 into power, and power conversion section 307 converts output data of Npoint FFT section 304 into power. Adder 308 in the subsequent stage adds the power value converted by power conversion section 306 and the power value converted by power conversion section 307. The averaging unit 309 averages the power values ​​of the power value sequence added by the adder 308 (the number of data points in one sequence is N points) using M sequences and M power values ​​obtained for each frequency bin, and outputs the result as a power spectrum. Based on this power spectrum information, the interference wave detection unit 105 detects the presence or absence of an interference wave as described above. When the communication method determination unit 106 places a command signal in a frequency band where an interference wave exists, it notifies the interference suppression unit 107 of the interference suppression amount information.

[0051] Weighting conversion unit 401 in interference suppression unit 107 generates a weighting coefficient W(k,i) for each bin for the frequency data after FFT based on this interference suppression amount information, and provides it to multipliers 404 and 405. In weighting coefficient W(k,i), k is a sample number (∈{1, 2, 3, ..}) that increases with the FFT period, i is a number corresponding to the BIN number of the FFT (∈{0, ​​1, ..N-1}, and N is the number of points. When interference suppression information is X(k,n) [dB], the value of W(k,n) is 10^(-X(k,n) / 20).

[0052] Here, a certain delay time τ occurs from when the N-point FFT units 304 and 305 output the data after FFT until when the weighting conversion unit 401 outputs the weighting coefficients to the multipliers 404 and 405 . Therefore, delay devices 402 and 403 in interference suppression section 107 delay the FFT output data from N-point FFT sections 304 and 305 by a time equivalent to this time delay τ, using a memory or the like.

[0053] FIG. 11 is a diagram showing the difference between when delay processing is performed and when it is not performed in delay devices 402 and 403 according to the present embodiment. If this delay processing is not applied, a state in which interference is not suppressed temporarily occurs for the received signal for the time τ from when the terminal station 01 detects interference to when it suppresses it. The state in which interference is not suppressed is shown by the shaded area in (1) of Figure 11. As a result, the command data sequence becomes partially erroneous due to the influence of the interference wave. Or, carrier synchronization or bit synchronization of the downstream demodulation unit {#1, #2, #3} is lost, which leads to a situation in which command data cannot be received until synchronization is achieved again.

[0054] On the other hand, when delay units 402 and 403 apply a time delay τ to the FFT output data, the received data is held up for time τ by delay units 402 and 403. During that time, weighting coefficients for suppressing interference are provided to multipliers 404 and 405, so that a state in which interference is not suppressed for the received signal never occurs even temporarily. This state is shown in (2) of FIG.

[0055] Multipliers 404 and 405 multiply the post-FFT data series output from delay devices 402 and 403 by the weighting coefficient W(k,i) output from weighting conversion section 401 . Here, the data sequence after FFT output from delay unit 402 is A(k,i), and the data sequence after FFT output from delay unit 403 is B(k,i). Here, k is the sample number (∈{1, 2, 3, ..}) that increases with the FFT period, i is the FFT BIN number (∈{0, ​​1, ..N-1}, and N is the number of points. At this time, multiplier 404 performs the calculation of the following (Equation 5), and multiplier 405 performs the calculation of the following (Equation 6).

[0056] AM(k,i) = A(k,i) × W(k,i) Equation (5) BM(k,i)=B(k,i)×W(k,i) Equation (6)

[0057] When no interference is detected, the values ​​of W(k,i) are all 1, and as a result, the input data of the multiplier is output as is. In other words, (AM(k,i)=A(k,i),BM(k,i)=B(k,i). On the other hand, if an interference wave is detected in frequency bin number n and the interference suppression information is X(k,n) [dB], the value of W(k,n) will be 10^(-X / 20), and each signal vector of A(k,n) and B(k,n) will be suppressed by 10^(-X / 20) times.

[0058] Next, an NPointIFFT unit 406 performs IFFT on the output data of the multiplier 404 to convert it into a data sequence in the time domain. Similarly, an NPointIFFT unit 407 performs IFFT on the output data of the multiplier 405 to convert it into a data sequence in the time domain. The adder 408 performs vector addition on the data output from the NPointIFFT unit 406 and the data output from the NPointIFFT unit 407 . Through the above series of processes, the terminal station 01 can reliably suppress interference waves from the moment they appear, while maintaining the continuity of the received signal time waveform.

[0059] FIG. 12 is a diagram showing an example of an uplink signal spectrum observation result (after interference suppression) according to the present embodiment. The difference between FIG. 12 and FIG. 5 is that the interference wave (b) is suppressed to less than the threshold value TH. As mentioned above, in the frequency band in which the interference wave (b) exists, the center frequencies of the three narrowband interference signals change dynamically within the range of that frequency band. In order to reliably suppress such interference waves that change dynamically on the frequency axis, the terminal station 01 quickly and repeatedly performs a series of processes from interference wave detection to interference suppression processing.

[0060] The frequency band in which the interference wave (a) in Fig. 7 exists has a lower power density Io [dBm / Hz] than the interference wave (c), and even if a BPSK command signal is placed, the SINR is strong enough to exceed the threshold value STH. In this case, the communication method determination unit 106 selects BPSK as the modulation method for the modulation unit #2 (202b) of the ground station 04, and specifies the center frequency as F2 in the frequency band in which the interference wave (a) exists, as shown in Fig. 7. Similarly, the communication method determination unit 106 selects BPSK as the modulation method for the modulation unit #3 (202c) of the ground station 04, and specifies the center frequency as F3 in the frequency band in which the interference wave (a) exists, as shown in Fig. 7.

[0061] If the power density of the interference wave (a) is as high as that of the interference wave (c) and the SINR is below the threshold value STH, the communication method determination unit 106 may specify the modulation method and frequency as follows. The communication method determination unit 106 may specify the modulation method and frequency only for the modulation unit #1 (202a) of the ground station 04 without specifying the modulation method and frequency for the modulation unit #2 (202b) and modulation unit #3 (202c) of the ground station 04. Alternatively, the communication method determination unit 106 may specify the modulation method (DSS) and frequency (F1) specified for the modulation unit #1 (202a) to the modulation unit #2 (202b) and modulation unit #3 (202c) in the same manner. Then, the SINR of the DSS command signal may be further improved by in-phase synthesis of three DSS command signals from the ground station 04 into one at the frequency F1.

[0062] The telemetry transmitter 110 transmits the center frequencies of the N channels as a telemetry signal to the ground station. The telemetry transmitter 110 also transmits the modulation method of each of the N channels in addition to the center frequency of each of the N channels to the ground station as a telemetry signal. Specifically, the following is done. 2 modulates each modulation method and center frequency information to modulation unit #1 (202a), modulation unit #2 (202b), and modulation unit #3 (202c) designated by the communication method determination unit 106 into a telemetry signal and transmits it. At this time, the telemetry transmission unit 110 modulates each modulation method and center frequency information together with telemetry information in other terminal stations into a telemetry signal and transmits it. In addition, each modulation method and center frequency information designated by the communication method determination unit 106 is periodically updated. Therefore, the telemetry transmission unit 110 modulates the "expiration date information" corresponding to the expiration date of each modulation method and center frequency information into a telemetry signal and transmits it.

[0063] The "expiration date information" is time information that the terminal station 01 (communication method determination unit 106) notifies the ground station 04. The terminal station 01 waits for a command signal from the ground station 04 using each modulation method and center frequency information transmitted by telemetry until the time notified to the ground station 04. On the other hand, if the notified time has passed, the terminal station 01 will not necessarily wait using that modulation method and center frequency information, and may wait using a different modulation method and center frequency. The terminal station 01 communicates the above content to the ground station 04 using the "expiration date information."

[0064] The telemetry signal modulated in this manner is transmitted to the ground station 04 via the transmitting antenna 03 of the terminal station 01 .

[0065] At this point, the process up to "Step S2: Determine uplink frequency and modulation method, and transmit by telemetry. Implement interference suppression if necessary" in the operational flow diagram shown in Figure 4 has been completed.

[0066] <Step S3: Send command signal from ground station> The telemetry receiving unit 200 receives the telemetry signal and extracts information on the center frequency of each of the N channels and the modulation method of each of the N channels from the telemetry signal. More specifically, this is as follows. The ground station 04 shown in Fig. 3 receives a telemetry signal from the terminal station 01 via the receiving antenna 05. The telemetry receiver 200 demodulates the telemetry signal from the terminal station 01. The telemetry receiver 200 extracts, from the demodulated telemetry data, the modulation method and center frequency information for each modulation unit 202 designated by the communication method determination unit 106 of the terminal station 01, and the expiration date information. In this embodiment, the telemetry receiver 200 extracts the modulation method and center frequency information for each modulation unit #1 (202a), modulation unit #2 (202b), and modulation unit #3 (202c), and the expiration date information.

[0067] Next, the telemetry receiving unit 200 transmits a command signal from the ground station 04 to the terminal station 01 based on each modulation method and center frequency information designated by the communication method determining unit 106 by the expiration date. Then, the telemetry receiving unit 200 checks whether there is a possibility that the terminal station 01 will be able to receive them. If there is a possibility, the telemetry receiving unit 200 distributes each modulation method and center frequency information designated by the communication method determining unit 106 to each modulation unit. On the other hand, if the information transmission is delayed for some reason and does not arrive in time for the expiration date, the telemetry receiving unit 200 discards each modulation method and center frequency information designated by the communication method determining unit 106 without distributing it to each modulation unit.

[0068] The reason for discarding is that even if the ground station 04 transmits a command signal to the terminal station 01 based on the specified modulation method and center frequency information after the expiration date, the standby frequency or modulation method setting of the terminal station 01 may have already been updated to a new setting. In this case, the terminal station 01 will be unable to demodulate the command signal normally, so the telemetry receiver 200 will not distribute the command signal and will wait for the next specified information to be sent from the terminal station 01. The telemetry receiving unit 200 also outputs telemetry data from other terminal stations 01 as monitor information.

[0069] On the other hand, the data duplicating unit 201 copies the command data to be transmitted to the terminal station into N copies. The N modulation units modulate and frequency convert each of the N pieces of copied command data based on the center frequency for the N channels, and output them as command signals. The N modulation units modulate each piece of copied command data using the modulation method for each of the N channels, and then transmit it to the terminal station using the center frequency for each of the N channels. Specifically, it is as follows. The data duplicating unit 201 shown in FIG. 3 duplicates the command data from the ground station into three and outputs them as CMD Data #1, CMD Data #2, and CMD Data #3. The modulation unit #1 (202a) modulates and outputs the command data CMD Data #1 output from the data duplication unit 201 based on the modulation method (Mod Type #1) and center frequency information (Fc #1) for the modulation unit #1 (202a) extracted by the telemetry receiving unit 200. Here, since Mod Type #1 is the DSS selected by the communication method determination unit 106 and Fc #1 is the F1 selected by the communication method determination unit 106, the modulation unit #1 (202a) outputs a DSS-modulated command signal with a center frequency of F1.

[0070] The modulation unit #2 (202b) modulates and outputs the command data CMD Data #2 output from the data duplication unit 201 based on the modulation method (Mod Type #2) and center frequency information (Fc #2) for the modulation unit #2 (202b) extracted by the telemetry receiving unit 200. Here, since Mod Type #2 is BPSK selected by the communication method determination unit 106 and Fc #2 is F2 selected by the communication method determination unit 106, the modulation unit #2 (202b) outputs a BPSK-modulated command signal with a center frequency of F2.

[0071] The modulation unit #3 (202c) modulates and outputs the command data CMD Data #3 output from the data duplication unit 201 based on the modulation method (Mod Type #3) and center frequency information (Fc #3) for the modulation unit #3 (202c) extracted by the telemetry receiving unit 200. Here, since Mod Type #3 is BPSK selected by the communication method determination unit 106 and Fc #3 is F3 selected by the communication method determination unit 106, the modulation unit #3 (202c) outputs a BPSK-modulated command signal with a center frequency of F3.

[0072] A downstream combiner 203 combines the modulated signals output from the modulators #1 (202a), #2 (202b), and #3 (202c), and then power-amplifies the combined signal and outputs it. Furthermore, the downstream transmitting antenna 06 transmits the signal output from the combiner 203 to the terminal station 01 .

[0073] At this point, the process up to "Step S3: Transmitting a command signal based on the result of the determination by the terminal station" in the operational flow diagram shown in FIG. 4 has been completed.

[0074] <Step S4: Uplink signal spectrum observation (after sending command signal)> The terminal station 01 starts preparations for receiving a command signal from the ground station 04 while the ground station 04 is executing the process of step S3. Specifically, the communication method determination unit 106 sets the modulation method and frequency specified for the modulation unit #1 (202a) in the demodulation unit #1 (108a). Then, when a command signal is transmitted from the modulation unit #1 (202a), the demodulation unit #1 (108a) prepares to receive and demodulate the command signal. Similarly, the communication method determination unit 106 sets the modulation method and frequency specified for the modulation unit #2 (202b) in the demodulation unit #2 (108b). Then, when a command signal is transmitted from the modulation unit #2 (202b), the demodulation unit #2 (108b) prepares to receive and demodulate the signal. Similarly, the communication method determination unit 106 sets the modulation method and frequency specified for the modulation unit #3 (202c) in the demodulation unit #3 (108c). Then, when a command signal is transmitted from the modulation unit #3 (202c), the demodulation unit #3 (108c) prepares to receive and demodulate the signal.

[0075] FIG. 13 is a diagram showing an example of an uplink signal spectrum observation result (after transmitting a command signal) according to the present embodiment. Figure 13 shows the uplink signal spectrum while the ground station 04 is transmitting a command signal. The difference from Figure 5 is that the spectrum of three command signals (modulated wave #1, modulated wave #2, modulated wave #3) from the ground station 04 is added.

[0076] Next, the spectrum measurement unit 104 of the terminal station 01 measures the uplink signal spectrum shown in FIG. 13 to which the three modulated waves from its own system have been added, and transmits the measurement result to the interference wave detection unit 105 at the subsequent stage.

[0077] At this point, the process up to "Step S4: Observing the uplink signal spectrum" in the operational flow diagram shown in FIG. 4 has been completed.

[0078] <Step S5: Command signal demodulation process> Each of the demodulators 108 waits for a command signal in the modulation method and frequency specified by the communication method determination unit 106. The demodulators #1 (108a), #2 (108b), and #3 (108c) receive the modulated waves #1, #2, and #3 to be demodulated in the same modulation method and frequency. The modulation method of the transmitting side (earth station 04 side) and the modulation method of the receiving side (terminal station 01 side) match, and the frequency of the transmitting side (earth station 04 side) and the frequency of the receiving side (terminal station 01 side) match. Therefore, the demodulators #1 (108a), #2 (108b), and #3 (108c) easily establish carrier bit synchronization with the command signal and realize demodulation of the command signal.

[0079] As described above, the demodulator #1 (108a) that demodulates the modulated wave #1 has the interference wave (b) suppressed in advance by the interference suppression unit 107 at the previous stage as shown in Fig. 12. Therefore, synchronization and demodulation of the command signal are realized without being affected by the interference wave (b). Note that each of the demodulators 108a, 108b, and 108c does not make a hard decision on the command demodulated signal to a binary value {0, 1}, but outputs it as a command demodulated signal (I+jQ), which is a signal vector. Each demodulator 108a, 108b, and 108c also outputs the received signal power to interference plus noise power ratio (S / IN) and the reception level obtained during the demodulation process as accompanying information. Note that S / IN has the same meaning as the above-mentioned SINR, and is simply expressed differently.

[0080] FIG. 14 is a diagram showing the state of calculation of the reception S / IN and reception level when demodulating a command signal according to the present embodiment. The demodulators 108b and 108c demodulate the BPSK modulated command signal. The demodulator 108a demodulates the DSS, but after despreading, it demodulates the BPSK modulated command signal in the same way as the other demodulators. Therefore, in any demodulation section, the received signal point after BPSK demodulation will converge to one of two points, indicated by the symbols {◯, ●}, shown in FIG. 14, if there is no effect of noise or interference. The phase θ [deg] is divided into the first quadrant (-90≦θ<+90) and the second quadrant (-90>θ, θ≧+90) with the boundary being ±90 degrees. At this time, when each demodulator first calculates the received S / IN and reception level, it degenerates the signal points scattered in the two quadrants into the first quadrant. Specifically, assuming that the amplitude of Ich is I, the amplitude of Qch is Q, the amplitude after degeneration is Ic, and the amplitude after degeneration is Qd, the degeneration process is performed according to the following equation (7).

[0081] Ic=+I, Qc=+Q (I≧0) Ic=-I, Qc=-Q (I<0) Equation (7)

[0082] In Fig. 14, the symbol △ indicates each signal point after degeneration. In Fig. 14, the symbol ● indicates the average vector obtained by integrating each signal point vector after degeneration and then dividing by the average number of integrations, which is the signal component of the command. The squared value of the average vector length is the power (S) of the signal component. Therefore, the demodulators 108a, 108b, and 108c each obtain the received signal power by the above-mentioned vector averaging process and the process of squaring the average vector length (S1, S2, and S3).

[0083] On the other hand, in Figure 14, the distance between the symbol ● and each symbol △, for example the arrow part in Figure 14, is the sum of the residual interference component and the noise component, and the average of the squared values ​​of this distance becomes the sum (IN) of the residual interference wave power and the noise power. Therefore, the demodulation units 108a, 108b, and 108c calculate the vector length of the residual interference component + noise component, i.e., the arrow portion of ``residual interference component + noise component'' in Figure 14, and calculate the sum of the residual interference wave power and the noise power by squaring the vector length and averaging it (IN1, IN2, IN3). Finally, demodulators 108a, 108b, and 108c respectively calculate the ratio between the two and output them as signal power to interference, noise power ratios (S1 / IN1, S2 / IN2, and S3 / IN3).

[0084] The combiner 109 combines the N command signals demodulated by the N demodulators, and outputs the combined signal as command data. Specifically, this is as follows. The combiner 109 in FIG. 2 converts the S D / IN D (where D∈{1,2,3}, D corresponds to the demodulation unit number #), the combiner 109 combines the three demodulated command demodulated signals output from each of the demodulators 108. Specifically, the combiner 109 combines the three demodulated command demodulated signals output from demodulator #1 (108a), demodulator #2 (108b), and demodulator #3 (108c).

[0085] The synthesis method is to use three S / IN (i.e. S D / IN DA selection and combination method is used, which selects and outputs the command demodulation signal with the highest (=most likely) S / IN from (D∈{1,2,3}). Alternatively, maximum ratio combining may be used, in which the S / IN (=likelihood) of each of the three command demodulation signals is weighted before vector combination. If a time delay difference occurs among the three command demodulated signals when they are combined, the combiner 109 detects a synchronization word (=unique word) added to the header of each command data from the command demodulated signal, and then combines the signals after adjusting the time delay using the reception timing of the detected synchronization word so as to cancel out the time delay difference among the three command demodulated signals.

[0086] The combiner 109 performs hard decision on the combined demodulated signal, which is obtained by combining the three command demodulated signals in this manner, to a binary value {0, 1}, and outputs the result of the hard decision as command demodulated data. By synthesizing these three command demodulated signals, it is possible to obtain an effect of improving reception sensitivity through frequency diversity.

[0087] FIG. 15 is a diagram showing an example of an uplink signal spectrum observation result (after interference wave (a) changes) according to the present embodiment and an uplink frequency and modulation method designation for modulated wave #2. For example, as shown in Fig. 15, the S / IN of modulated wave #2 may decrease due to a sudden spectrum change of the interference wave (a), and as a result, the demodulation unit #2 (108b) may fall into a state where it cannot demodulate the command signal normally. Even in such a case, the command demodulation signal from another demodulation unit is selected (selective synthesis), or the command demodulation signal from demodulation unit #2 (108b) is weighted lightly and the command demodulation signal from another demodulation unit is weighted heavily before being synthesized (maximum ratio synthesis). Therefore, the command demodulation data after synthesis is not affected by this, and the terminal station 01 can continue to obtain stable command demodulation data. In addition, each of the above S D / IN D (D∈{1,2,3}), each received signal power S D(D∈{1,2,3}) and each synchronization state of the demodulators 108a, 108b, 108c are also transmitted to the communication method determination unit .

[0088] At this point, the process up to "Step S5: demodulating the command signal" in the operational flow diagram shown in FIG. 4 has been completed.

[0089] <Step S6: Update the uplink frequency and modulation method as necessary, and transmit by telemetry. Implement interference suppression as necessary> The communication method determination unit 106 calculates the received signal power S D Based on the (D∈{1,2,3}) information, the threshold value to be provided to the interference wave detection unit 105 is updated. The threshold value TH before updating that has already been provided to the interference wave detection unit 105 is the one before receiving the command signal from the ground station 04, and was determined based on the noise level generated in the amplifier 99 of the terminal station 01, etc.

[0090] In contrast, the newly updated threshold value THR(i) (where i is a BIN number, i∈{0, 1, . . . , N-1}) is generated for the state in which a command signal is received from the ground station 04. The shape of the newly updated threshold value THR(i) is determined by the command signal reception conditions from the ground station 04. An example of threshold value THR(i) is shown by the dotted line in FIG. 13. Since each command signal is received, with the threshold value TH before the update, the spectrum of the command signal exceeds the threshold value TH in the signal band in which the command signal exists, and as a result, the command signal is erroneously determined to be an interference wave. Therefore, the threshold is raised in the signal band where the command signal exists, and the threshold is set to the total value of the signal power and noise power (not including the interference power) in BIN units, as shown by the dotted line in Fig. 13 as the threshold THR(i). This makes it possible to detect only the signal bands where the interference waves a, b, and c exist, without erroneously determining that the command signal is an interference wave, even while each command signal is being received.

[0091] A specific method for generating the threshold value THR(i) will be described. The information required to generate the threshold THR(i) is the power of each received signal S D (D∈{1,2,3}), the modulation method and center frequency information set in demodulator #1 (108a), demodulator #2 (108b), and demodulator #3 (108c), and the threshold value TH used when the aforementioned command signal is not received.

[0092] The communication method determination unit 106 first determines the bandwidth B of each command signal from the modulation methods designated for the modulation unit #1 (202a), the modulation unit #2 (202b), and the modulation unit #3 (202c) of the ground station 04. D (where D∈{1,2,3}). The bandwidth of the modulated wave can be determined from the modulation method. Next, the communication method determination unit 106 determines the center frequency information F D (where D∈{1,2,3}), calculate three frequency bands in which the command signal exists. The three frequency bands ∈{F1±0.5*B1, F2±0.5*B2, F3±0.5*B3}.

[0093] If there is no interference wave, only noise components exist at frequencies other than the frequency band {F1±0.5*B1, F2±0.5*B2, F3±0.5*B3}. Therefore, for frequency bin numbers corresponding to frequency bands where the command signal does not exist, THR(i) is set to TH. On the other hand, the THR(i) set for the frequency band in which the command signal exists is D (D∈{1,2,3}) and the bandwidth of the command signal B D (D∈{1,2,3}), the center frequency information of the command signal F D (where D∈{1,2,3}) etc.

[0094] The following describes a method for calculating THR(i) to be set in the frequency band in which the command signal exists. Since BF is the bandwidth of the frequency bin of the FFT, the signal power per 1 bin of the command signal received from the modulation unit #D (where D∈{1,2,3}) is SF D [dBm / bin] is calculated using the following formula: Signal power SF D Since [dBm / bin] needs to be the received power before interference wave suppression, the amount of suppression per bin given to each command signal band by the interference suppression unit 107 is Z D [dB / bin], it is shown in the following equation (8). For example, in the case of a command signal i(∈{1,2,3}) that is not suppressed by interference, Z i For command signal i(∈{1,2,3}) with [dB / bin]=0dB and 10dB interference suppression, Z i [dB / bin]=10dB.

[0095] science fiction D [dBm / bin]=10×log 10 (S D ×BF / B D )+Z D [dB / bin]+Px[dB] Formula (8)

[0096] However, Px is a fixed value that depends on the design content, and is the relative reception level per bin, 10 × log 10 (S D ×BF / B D ) [dB / bin] to the actual receive level per bin [dBm / bin].

[0097] In this case, THR(i) to be set for the frequency band in which the command signal exists is calculated from the sum of the signal power per bin and the ATT-controlled noise power, as shown in the following equation (9).

[0098] THR(i) = 10 × log 10 {10^(SF D / 10)+10^((NZ-ATT) / 10)}[dBm / bin]+ΔTH[dB] Equation (9)

[0099] Here, NZ [dBm / bin] is the noise power in the frequency bin band, ATT [dB] is the control value that the automatic gain control unit 102 gives to the variable gain unit 101, and ΔTH [dB] is the relative threshold value.

[0100] Each received signal power S D As shown in FIG. 14, (D∈{1,2,3}) is the received power of the command signal that does not include residual interference components or noise components. Therefore, the SF D [dBm / bin] is not affected by interference or noise levels. Therefore, the THR(i) calculated by equation (9) is not affected by the appearance or disappearance of interference.

[0101] While monitoring this information, the communication method determination unit 106 determines whether to maintain the already determined center frequencies (F1, F2, F3) of the command signals and their respective modulation methods {DSS, BPSK} as they are or to change them. Prior to the determination, the communication method determination unit 106 calculates the S D / IN D (D∈{1,2,3}). In the initial stage before receiving the command signal, the communication method determination unit 106 uses the SINR predicted values ​​calculated by the above formulas (2), (3), and (4). However, after receiving the command signal, the S D / IN D (D∈{1,2,3}), received power S D (D∈{1,2,3}) Next, the communication method determination unit 106 D / IN D Compare the STH with (D∈{1,2,3}).

[0102] Here, the STH value differs depending on the modulation method of the command signal, so STH is set for each of the three command signals. D (D∈{1,2,3}). The communication method determination unit 106 determines S D / IN D STHD Is it the above (S D / IN D ≧ STH D ), or not (S D / IN D < STH D ) is detected.

[0103] S D / IN D is maintained at STH D or more, the communication method determination unit 106 does not change each modulation method (Mod Type#D) and center frequency information (Fc#D) specified by the communication method determination unit 106 (where D ∈ {1, 2, 3}). On the other hand, as shown in FIG. 15, the spectrum of the interference wave (a) changes to become the interference wave (a)’, and there is a case where the SINR of the modulated wave #2, which is the spectrum of the command signal, is lower than STH (S2 / IN2 < STH2). In this case, since the quality of the command communication using the modulated wave #2 is not sufficiently ensured, the communication method determination unit 106 considers changing the modulation method (Mod Type#2) and center frequency information (Fc#2) of the modulated wave #2. Specifically, the communication method determination unit 106 considers resetting the modulation method (Mod Type#2) and center frequency information (Fc#2) of the modulated wave #2. The communication method determination unit 106 considers resetting the modulation method (Mod Type#2) and center frequency information (Fc#2) of the modulated wave #2 based on the current interference wave detection information detected by the interference wave detection unit 105, the current power spectrum information measured by the spectrum measurement unit 104, and each modulation method (Mod Type#D) and center frequency information (Fc#D) currently specified by the communication method determination unit 106.

[0104] In considering this, the communication method determination unit 106 first calculates the SINR based on the above formulas (2), (3), and (4). Note that the frequency band where the own wave (= modulated wave #2) exists is excluded from the calculation target. Also, compared with the initial stage when the terminal station #1 has not yet received the command signal, the modulated wave #1 and the modulated wave #3 exist. These are measured as interference components based on the formula (2a). Here, the S [dBm] described in equations (2), (3), and (4) is the measured value, that is, the received signal power spectral density SF2 [dBm / bin] calculated by equation (8), to which the number of bins corresponding to the signal bandwidth of modulation wave #2 is converted to dB and added (= SF2 [dBm / bin] + 10 * log 10 (B2 / BF)) may be used. However, B2 is the signal bandwidth of modulation wave #2.

[0105] Based on the calculated SINR information, the communication mode determination unit 106 searches for the center frequency FC and modulation mode Mod Type at which the SINR of modulation wave #2 is equal to or greater than the threshold value STH2. The communication mode determination unit 106 extracts a plurality of candidates for {center frequency, modulation mode} that are equal to or greater than the threshold value STH2. Here, when Mod Type is DSS, the communication mode determination unit 106 searches separately for the case without interference suppression and the case with interference suppression.

[0106] Also, when the communication mode determination unit 106 temporarily arranges modulation wave #2 at the center frequency FC at which the SINR of modulation wave #2 is equal to or greater than the threshold value STH2, it checks whether the signal spectrum of modulation wave #2 overlaps with the signal spectrum of another modulation wave #1 or modulation wave #3. For example, when the spectrum of modulation wave #2 overlaps with the spectrum of modulation wave #1, the communication mode determination unit 106 calculates the predicted SINR value SINRE1 of modulation wave #1. Since the predicted value SINRE1 has the signal spectrum of modulation wave #2 added as an interference component, it will decrease compared to each S1 / IN1 measured by the demodulation unit 108a (SINRE1 < S1 / IN1). Therefore, even for the center frequency FC and modulation mode Mod Type at which the SINR of modulation wave #2 is equal to or greater than the threshold value STH2, if the predicted value SINRE1 of modulation wave #1 is below the threshold value STH2, the communication mode determination unit 106 excludes that {center frequency, modulation mode} from the candidates.

[0107] Hereinafter, a specific method for calculating the predicted value SINRE1 will be shown. First, the communication mode determination unit 106 determines the interference + noise power IN currently received by the demodulation units 108a, 108b, and 108c D(D∈{1,2,3}) is calculated using the following formula (10).

[0108] IN D [dBm]=SF D [dBm / bin]+10*log 10 (B D / BF)[dB]-10*log10(S D / IN D )[dB] Equation (10)

[0109] However, B D (D∈{1,2,3}) is the signal bandwidth of modulated wave #D.

[0110] Next, the interference + noise power INA when the corresponding modulated wave is added as an interference wave D [dBm] (D∈{1,2,3}). For example, if modulated wave #2 interferes with modulated wave #1, calculate the interference+noise power INA1 [dBm] of modulated wave #1 after modulated wave #2 interferes with modulated wave #1. Here, the interference power IS2 [dBm] that modulated wave #2 causes to modulated wave #1 is calculated by the following formula: where SF2 [dBm / bin] is the value obtained by formula (8), and Bs is the bandwidth where the spectra of modulated wave #2 and modulated wave #1 overlap.

[0111] IS2[dBm]=SF2[dBm / bin]+10*log 10 (Bs / BF)[dB] Formula (10a)

[0112] Therefore, the interference plus noise power INA2 [dBm] and the expected value SINRE1 [dB] when modulated wave #2 is added as an interference wave are calculated by the following equations (11) and (12).

[0113] INA2[dBm]=10*log 10 (10^(IN D / 10)+10^(IS D / 10)) Equation (11) SINRE1[dB]=SF1[dBm / bin]+10*log 10(B1 / BF)[dB]-INA2[dBm] Formula (12)

[0114] In addition, when the modulation method of modulated wave #1 is DSS and demodulator #1 (108a) performs interference suppression, the interference power IS2 [dBm] that modulated wave #2 causes to modulated wave #1 is suppressed, but the received signal power of modulated wave #1 is also suppressed by the bandwidth Bs where the spectra of modulated wave #2 and modulated wave #1 overlap. Therefore, SINRE1 [dB] when interference suppression is performed is calculated by the following equation (13) without using the above equation (12).

[0115] SINRE1[dB]=SF1[dBm / bin]+10*log 10 ((B1-Bs) / BF)[dB]-IN D [dBm] Formula (13)

[0116] Even when the spectra of modulated wave #2 and modulated wave #1 overlap in this manner, if the SINRE1 [dB] calculated using equations (12) and (13) is greater than or equal to threshold value STH1 and the SINR of modulated wave #2 is greater than or equal to threshold value STH2, the communication method determination unit 106 also reserves the {center frequency, modulation method} at that time as a candidate for FC#2 and Mod Type#2.

[0117] The communication method determination unit 106 determines, from among the multiple {center frequency, modulation method} candidates obtained as described above, FC#2 and Mod Type#2 based on those that achieve the highest overall SINR for each of the modulated waves #1 to #3 against the respective threshold values ​​STH.

[0118] In this embodiment, the case where the center frequency and modulation method of modulated wave #2 are changed and the spectrum of modulated wave #2 and modulated wave #1 overlap is described as an example. However, the communication method determination unit 106 also determines the SINR or SINRE in the same manner when the center frequency and modulation method of other modulated wave #1 or modulated wave #3 are changed and when the spectrums overlap. DBy finding (D∈{1,2,3}), a new center frequency and modulation method are determined.

[0119] 15 indicates the destination of modulated wave #2 determined by the communication method determination unit 106. The center frequency is changed from F2 to F2', and the modulation method remains BPSK. FIG. 15 shows a situation in which in frequency bands where interference waves (a)' and (c) exist, the interference wave level is high and the SINR of modulated wave #2 falls below threshold value STH2 in most frequency ranges. 15, in the frequency band where modulated wave #1 exists and in the frequency region where interference wave (b) does not exist, the spectrum power density of modulated wave #1 (DSS) is low, so the SINR of modulated wave #2 exceeds the threshold value STH2. In this case, if the center frequency of modulated wave #2 is moved from F2 to F2', the communication quality of the command signal using modulated wave #2 can be ensured.

[0120] On the other hand, when the center frequency of modulated wave #2 is shifted to F2', modulated wave #1 is added as an interference component in addition to the interference wave (b). In Fig. 15, if modulated wave #2 is BPSK (narrowband signal), and interference including modulated wave #2 is suppressed, the predicted value SINRE1 [dB] exceeds the threshold value STH1. In view of this, the communication method determining unit 106 determines to change only the center frequency from F2 to F2', without changing the modulation method of modulated wave #2 from BPSK. In response to this change, demodulator #2 (108b) receiving modulated wave #2 temporarily stops demodulation processing, changes the center frequency from F2 to F2', and waits for BPSK modulated modulated wave #2.

[0121] In response to the change in the center frequency of modulated wave #2, the telemetry transmitter 110 modulates the modulation method and center frequency information for each of the designated modulation units #1 (202a), #2 (202b), and #3 (202c) updated by the communication method determination unit 106 into a telemetry signal while adding "expiration date information" to the information, and transmits it. The only difference from the content transmitted up until now is the center frequency of modulated wave #2 in this example.

[0122] At this point, the process up to "Step S6: Update the uplink frequency and modulation method as necessary, and transmit by telemetry. Implement interference suppression as necessary" shown in the operational flow diagram of FIG. 4 has been completed.

[0123] The telemetry receiving unit 200 of the ground station 04 extracts each modulation method and center frequency information for the modulation unit #1 (202a), modulation unit #2 (202b), and modulation unit #3 (202c) from the demodulated telemetry data in the same manner as before. Furthermore, the telemetry receiving unit 200 checks from the "expiration date information" that the expiration date will be met, and then distributes each modulation method and center frequency information designated by the communication method determining unit 106 to the modulation unit #1 (202a), modulation unit #2 (202b), and modulation unit #3 (202c).

[0124] At this point, the center frequency information (Fc#2) delivered to modulation unit #2 (202b) is changed from F2 to F2'. In accordance with this change, modulation unit #2 (202b) changes the center frequency from F2 to F2' when BPSK modulating command data CMD Data#2 output from data duplication unit 201 and outputs the changed center frequency. Meanwhile, the method and center frequency of each modulated wave output from modulation unit #1 (202a) and modulation unit #3 (202c) do not change. The downstream combiner 203 combines these three modulated waves, then amplifies the power and outputs the combined wave.

[0125] FIG. 16 is a diagram showing an example of an uplink signal spectrum observation result according to the present embodiment (after changing the frequency of modulated wave #2). Figure 16 shows the uplink signal spectrum after the center frequency of modulated wave #2 is changed. Comparing it with Figure 13, it can be seen that the center frequency of modulated wave #2 has changed. Through this series of frequency change processes, the quality of command communication using modulated wave #2 is once again sufficiently ensured.

[0126] FIG. 17 is a diagram showing an example of an uplink signal spectrum observation result according to the present embodiment and an uplink frequency and modulation method designation for each modulated wave. FIG. 17 shows the spectrum of the uplink signal after that, and the interference wave has changed compared to FIG.

[0127] Specifically, the interference wave (c) remains stationary, while the interference wave (b) changes to interference wave (b)', the interference wave (a)' disappears, and the interference wave (d) appears. The interference wave (b) was composed of three narrowband interference waves, but the interference wave (b)' shows that the number of narrowband interference waves has increased from three to eight, and the center frequencies of each wave change dynamically within the range indicated by the dotted arrows in Figure 17. The reception level of each narrowband interference wave constituting the interference wave (b)' is higher than that of modulated wave #2 or modulated wave #3. Therefore, when the state of the interference wave changes in this way, every time the spectrum of modulated wave #2 and modulated wave #3 overlaps with that of interference wave (b)', demodulator #2 (108b) or demodulator #3 (108c) loses carrier synchronization and bit synchronization. As a result, the quality of command communication using modulated wave #2 or modulated wave #3 is not sufficiently ensured (S2 / IN2 <STH2,S3 / IN3<STH3)。 In addition to the interference wave (b)', the spectrum of modulated wave #1 also overlaps with the new interference wave (d), and as a result, if interference suppression is performed, more than half of the own wave band will be lost. As a result, the quality of command communication using modulated wave #1 cannot be sufficiently ensured (S1 / IN1 <STH1)。

[0128] In this case, the communication method determination unit 106 considers changing the modulation method (Mod Type#D, D∈{1,2,3}) and center frequency information (Fc#D, D∈{1,2,3}) of each modulated wave. The specific signal processing process for this consideration is the same as described above. In FIG. 17, {305, 306, 307} and {F1', F2", F3'} indicate the modulation method (Mod Type#D, D∈{1,2,3}) and center frequency information (Fc#D, D∈{1,2,3}) of each new modulated wave determined by the communication method determination unit 106.

[0129] The details will be explained below. The communication method determination unit 106 changes the center frequency from F1 to F1' while keeping the modulation method of the modulated wave #1 as DSS, thereby avoiding spectrum overlap with the interference wave (d) and improving S1 / IN1. This ensures sufficient command communication quality of the modulated wave #1 (S1 / IN1≧STH1). Next, the communication method determination unit 106 changes the modulation method of modulated wave #2 from BPSK to DSS, changes the center frequency from F2' to F2", and performs control to reduce the influence of interference due to interference wave (b)' and improve S2 / IN2 by setting interference suppression. Finally, the communication method determination unit 106 performs control to avoid spectrum overlap caused by the interference wave (b)' and improve S / IN3 by changing the center frequency from F3 to F3' while keeping the modulation method of modulated wave #3 as BPSK. In this case, modulated wave #3 and modulated wave #2 will interfere with each other, but even so, command communication quality is sufficiently ensured (S2 / IN2≧STH2, S3 / IN3≧STH3).

[0130] FIG. 18 is a diagram showing an example of an uplink signal spectrum observation result according to the present embodiment. FIG. 18 shows the uplink signal spectrum after changing the modulation method (Mod Type#D, D∈{1,2,3}) and center frequency information (Fc#D, D∈{1,2,3}) of each modulated wave. In this way, the wireless communication system 500 according to this embodiment can maintain the communication quality of the command signal while responding to various changes in interference waves by changing not only the center frequency of the command signal but also the modulation method.

[0131] If the frequency range of the interference wave (b)' widens and spectrum overlap with the modulated wave #3 occurs even when the center frequency is changed to F3', a frequency hopping (FH) method may also be prepared as a modulation method and FH may be selected. The dashed line 308 in Fig. 18 indicates the frequency range of FH. By frequency hopping the modulated wave #3 in this way, the time rate at which spectrum overlap with the interference wave (b)' occurs can be reduced, improving the SINR.

[0132] In this case, by performing frequency hopping, when terminal station 01 demodulates modulated wave #1 and modulated wave #2, modulated wave #3 has an effect as an interference wave, but by suppressing the interference before demodulation, it is possible to prevent a reduction in SINR and maintain communication quality. On the other hand, when demodulating the frequency hopped modulated wave #3, modulated waves #1 and #2 have an effect as interference waves, but since the power density of modulated waves #1 and #2 is low, the increase in SINR is small, and the communication quality of the command signal using modulated wave #3 can be maintained.

[0133] In this way, in preparation for the case where a new modulation method is required, the circuits of each modulation unit (202a, 202b, 202c) and each demodulation unit (108a, 108b, 108c) may be configured to be rewritable using an FPGA. FPGA is an abbreviation for Field Programmable Gate Array. Circuit data for rewriting may be stored in advance in a memory (not shown) of the terminal station 01, or may be transmitted from the ground station to the terminal station 01 together with a command signal. Alternatively, a microprocessor may be used instead of an FPGA to be similarly configured to be rewritable. In this case, software programs related to the modulation processing performed in each modulation unit (202a, 202b, 202c) and software programs related to the demodulation processing performed in each demodulation unit (108a, 108b, 108c) may be stored in a memory (not shown) of the terminal station 01, or may be transmitted from the ground station to the terminal station 01 together with a command signal.

[0134] In this embodiment, two types of modulation methods (BPSK, DSS) have been described, but if it is determined that a combination of FH and DSS is more suitable, for example, two types of modulation methods, FH and DSS, can be selected during operation. In this way, the number of channels N may be 2 or more, and the modulation methods may include direct sequence spread spectrum (DSS) and frequency hopping (FH). The terminal station 01 may transmit a spectrum of the frequency hopping (FH) method and a spectrum of the direct sequence spread spectrum (DSS) in a state where they are overlapped on the frequency axis. This determination may be made by the communication method determination unit 106 of the terminal station 01, an operator of the ground station 04, or a computer owned by the ground station. When the determination is made by the ground station 04, the terminal station 01 periodically transmits power spectrum information measured by the spectrum measurement unit 104 to the ground station 04 via the telemetry transmission unit 110 as information for the determination.

[0135] As shown in the above flow, the communication method determination unit 106 determines an appropriate center frequency and modulation method for the command signal for various dynamically changing interference conditions. For this reason, the communication method determination unit 106 may be configured with software and may implement artificial intelligence (AI) that determines an appropriate center frequency and modulation method for the command signal while learning dynamically changing interference conditions by machine learning.

[0136] ***Explanation of the Effects of the Present Embodiment*** As described above, in the wireless communication system according to the present embodiment, the terminal station observes the uplink reception spectrum, and determines the center frequency and the appropriate modulation method of the command signal that realizes an appropriate reception SINR based on the observation result and the reception state of the demodulator. Then, the ground station transmits the command signal based on the frequency and the modulation method of the command signal determined by the terminal station. The wireless communication system according to the present embodiment is a system in which the above operations between the terminal station and the ground station are repeated. Therefore, compared to a system in which the center frequency and the modulation method of the command signal are predetermined, the system has excellent interference avoidance. For example, in a system in which the center frequency and modulation method of a command signal are predetermined, if an interference wave exists in the center frequency band of a plurality of predetermined command signals, the command signal from the ground station will be affected by the interference wave and will not be able to reach the terminal station. However, in the wireless communication system according to this embodiment, the center frequency band of the command signal is not predetermined, but can be freely determined within the range of the system band, so there is a high degree of freedom in avoiding interference waves.

[0137] In addition, in a normal system, if the command signal from the ground station is affected by interference waves and does not reach the terminal station, the center frequency switching command that the ground station sends to the terminal station to avoid the interference also does not reach the terminal station, which causes the terminal station to be unable to escape from an uncontrollable state. On the other hand, in the wireless communication system according to the present embodiment, the terminal station notifies the ground station of a center frequency that is not affected by interference based on the received power spectrum information, and the ground station repeats the interference avoidance operation of transmitting a command signal at the center frequency notified by the terminal station. This prevents the terminal station from falling into an uncontrollable state due to the influence of interference.

[0138] In this embodiment, the terminal station 01 is configured to include an interference suppression unit 107, but this configuration is not essential. If the interference suppression unit 107 is not provided, the SINR improvement effect due to interference suppression cannot be obtained, and this places restrictions on the frequency allocation of each modulated wave performed by the communication method decision unit 106. However, the wireless communication system can maintain the operation of detecting and avoiding interference waves. Furthermore, if the interference suppression unit 107 is not provided, the effect of reducing the circuit scale can be obtained.

[0139] In this embodiment, the ground station 04 uses three modulated waves to simultaneously transmit three identical command data to the terminal station 01, and the terminal station 01 demodulates the three modulated waves and then combines them. However, the number of modulated waves (=number of channels) N is not limited to 3, and may be any number equal to or greater than 1. Here, when N=1, no gain can be obtained from the combining process performed by the combiner 109 of the terminal station 01. However, the wireless communication system can maintain the operation of detecting interference waves and avoiding them. Also, since both the modulation unit and demodulation unit can be configured as a single set, the effect of reducing the circuit scale of the ground station 04 and the terminal station 01 can be obtained.

[0140] ***Explanation of Hardware Configuration Example*** FIG. 19 is a diagram showing an example of a hardware configuration of each device in wireless communication system 500 according to the present embodiment. FIG. 20 is a diagram showing another example of the hardware configuration of each device in wireless communication system 500 according to the present embodiment. In the following description, each of the terminal stations and the ground stations of the wireless communication system 500 will be described as each device of the wireless communication system 500.

[0141] In FIG. 19, a case will be described in which the functions of each unit of each device in wireless communication system 500 are realized by software. Each device in the wireless communication system 500 is a computer. Each device in the wireless communication system 500 includes a processor 910 and other hardware such as a memory 921, an auxiliary storage device 922, an input / output interface 930, and a communication interface 950. The processor 910 is connected to the other hardware via a signal line 80 and controls the other hardware. The functions of each device in the wireless communication system 500 may be realized by software.

[0142] The processor 910 is a device that executes the functions of each device in the wireless communication system 500. The wireless communication program is a program that realizes the functions of each device in the wireless communication system 500. The processor 910 is an IC that performs arithmetic processing. Specific examples of the processor 910 are a CPU, a DSP, and a GPU. IC is an abbreviation for Integrated Circuit. CPU is an abbreviation for Central Processing Unit. DSP is an abbreviation for Digital Signal Processor. GPU is an abbreviation for Graphics Processing Unit.

[0143] The memory 921 is a storage device that temporarily stores data. Specific examples of the memory 921 are SRAM and DRAM. SRAM is an abbreviation for Static Random Access Memory. DRAM is an abbreviation for Dynamic Random Access Memory. The auxiliary storage device 922 is a storage device that stores data. A specific example of the auxiliary storage device 922 is a HDD. The auxiliary storage device 922 may also be a portable storage medium such as an SD (registered trademark) memory card, CF, NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD. Note that HDD is an abbreviation for Hard Disk Drive. SD (registered trademark) is an abbreviation for Secure Digital. CF is an abbreviation for CompactFlash (registered trademark). DVD is an abbreviation for Digital Versatile Disk.

[0144] The input / output interface 930 is an interface for connecting an input / output device. Specific examples of the input / output interface 930 include a USB and an HDMI (registered trademark) port. USB is an abbreviation for Universal Serial Bus. HDMI (registered trademark) is an abbreviation for High-Definition Multimedia Interface.

[0145] The communication interface 950 is an interface for communicating with an external device. Specific examples of the communication interface 950 include an Ethernet (registered trademark) port, or a device for performing wireless communication.

[0146] The wireless communication program is executed in each device of the wireless communication system 500. The wireless communication program is loaded into the processor 910 and executed by the processor 910. The memory 921 stores not only the wireless communication program but also the OS. The OS is an abbreviation for Operating System. The processor 910 executes the wireless communication program while executing the OS. The wireless communication program and the OS may be stored in the auxiliary storage device 922. The wireless communication program and the OS stored in the auxiliary storage device 922 are loaded into the memory 921 and executed by the processor 910. Note that a part or all of the wireless communication program may be incorporated into the OS.

[0147] Each device in the wireless communication system 500 may include multiple processors that replace the processor 910. These multiple processors share the task of executing the wireless communication program. Each processor is a device that executes the wireless communication program, just like the processor 910.

[0148] Data, information, signal values ​​and variable values ​​used, processed or output by the wireless communication program are stored in the memory 921 , the secondary storage device 922 , or in registers or cache memory within the processor 910 .

[0149] The "unit" of each unit of each device of wireless communication system 500 may be read as a "circuit," "step," "procedure," "process," or "circuitry." The wireless communication program causes a computer to execute each process, with the "unit" of each unit of each device of wireless communication system 500 read as a "process." The "process" of each process of each device of wireless communication system 500 may be read as a "program," "program product," "computer-readable storage medium storing a program," or "computer-readable recording medium recording a program." The wireless communication method is a method performed by each device of wireless communication system 500 executing a wireless communication program. The wireless communication program may be provided in a state stored in a computer-readable recording medium, or may be provided as a program product.

[0150] 20 illustrates an example in which the functions of each unit of each device in the wireless communication system 500 are implemented by hardware. Specifically, each device in the wireless communication system 500 includes an electronic circuit 909 instead of a processor 910.

[0151] The electronic circuit 909 is a dedicated electronic circuit that realizes the function of each unit of each device in the wireless communication system 500. Specifically, the electronic circuit 909 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA is an abbreviation for Gate Array. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array.

[0152] The functions of each unit of each device in the wireless communication system 500 may be realized by one electronic circuit, or may be distributed across multiple electronic circuits.

[0153] As another modification, some of the functions of each unit of each device in the wireless communication system 500 may be realized by electronic circuits, and the remaining functions may be realized by software. Also, some or all of the functions of each unit of each device in the wireless communication system 500 may be realized by firmware.

[0154] Each of the processor and electronic circuits is also called a processing circuitry. In other words, the functions of each unit of each device in the wireless communication system 500 are realized by the processing circuitry.

[0155] Embodiment 2 In this embodiment, differences from and additions to the first embodiment will be mainly described. In this embodiment, components having the same functions as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

[0156] FIG. 21 is a diagram showing the results of uplink signal spectrum observation according to this embodiment, with the vertical axis indicating time and the horizontal axis indicating frequency. In the wireless communication system of the first embodiment, the modulation method and center frequency information of each modulated wave of the command signal are controlled based on the received power spectrum information. When an interference component periodically appears and disappears over the entire system band, as in the interference wave (e) shown in Fig. 21, and the SINR at the time of appearance is below the threshold value STH, the interference cannot be avoided by changing the center frequency alone, and the communication quality of the command signal may deteriorate. Therefore, in the wireless communication system of this embodiment, in addition to the modulation method and center frequency of the command signal, each parameter related to the time of the command signal is also controlled, thereby ensuring the communication quality of the command signal.

[0157] First, a method using time diversity will be described. The period during which the interference wave (e) repeatedly appears and disappears is Ts [seconds], the time during which it appears is Tx [seconds], and Ts≧Tx*2. In this case, in the wireless communication system of this embodiment, when the earth station 04 transmits two modulated waves #1 and #2, the transmission of modulated wave #2 is delayed by τ (≧Ts). This delay operation causes the positions of the command data affected by the interference wave (e) to be shifted between modulated wave #1 and modulated wave #2, without overlapping. Therefore, when terminal station 01 demodulates modulated wave #1 and modulated wave #2, if the modulated wave #1 is delayed by time τ to align the delay times of the two waves and then selectively combined, only the command data that is not affected by the interference wave (e) will be selected.

[0158] In order to realize such time diversity, the communication method determination unit 106 of the terminal station 01 creates a spectrogram using the periodically obtained received power spectrum, monitors the occurrence of two-dimensional interference waves including not only frequency but also time direction, and learns the characteristics. As shown in Fig. 21, when the appearance of the interference wave has periodicity in the time direction, the communication method determination unit 106 determines the delay time τ from the appearance period and appearance rate of the interference wave in addition to each modulation method and each center frequency information of the modulated waves #1 and #2. Then, the communication method determination unit 106 notifies the above to the ground station 04 via the telemetry line.

[0159] Another method that does not use time diversity is intermittent transmission. The intermittent transmission means transmits a command signal during the time period when the interference wave (e) disappears, as in the case of modulated wave #3 shown in Fig. 21, and does not transmit a command signal while the interference wave (e) is present. In this case, the communication method determination unit 106 of the terminal station 01 determines the intermittent transmission period, transmission time rate, and time to start intermittent transmission of the modulated wave #3 that can avoid the influence of the interference wave (e) from the created spectrogram in addition to the modulation method and center frequency information of the modulated wave #3. Then, the communication method determination unit 106 notifies the ground station 04 of these via the telemetry line.

[0160] In this way, in the wireless communication system of this embodiment, the terminal station 01 uses the spectrogram received to control the modulation method and center frequency of the command signal as well as each parameter related to the time of the command signal (delay time, intermittent transmission cycle, transmission time rate, and time to start intermittent transmission). This makes it possible to achieve stable communication quality of the command signal even under conditions where interference components repeatedly appear and disappear across the entire system band. The communication method determination unit 106 in the second embodiment may also be configured using software, and may be realized using artificial intelligence (AI) that determines an appropriate center frequency and modulation method for the command signal while learning by machine learning the interference that changes dynamically in the two dimensions of frequency and time.

[0161] Embodiment 3 In this embodiment, differences from the first and second embodiments and additional features to the first and second embodiments will be mainly described. In this embodiment, components having the same functions as those in the first and second embodiments are given the same reference numerals, and the description thereof will be omitted.

[0162] FIG. 22 is a diagram showing an example of the configuration of the ground station 04 according to this embodiment. FIG. 23 is a diagram showing an example of the configuration of the terminal station 01 according to the present embodiment. The number of channels N may be 2 or more, and the combiner 109 of the terminal station 01 may be configured with an error correction decoder, and the data replicator 201 of the ground station 04 may be configured with an error correction encoder.

[0163] In the first embodiment, the ground station 04 is provided with a data duplicating unit 201 that duplicates the command data into three pieces, but the data duplicating unit 201 may be replaced with an error correction coding unit 204 with a coding rate of 1 / 3. The error correction coding unit is also called an error correction coder. Fig. 22 shows an example of the configuration of the ground station 04 in this embodiment, and Fig. 23 shows an example of the configuration of the terminal station 01 in this embodiment. In this case, in the terminal station 01, the combiner 109 that combines the demodulated command signals is replaced with an error correction decoder 111 with a coding rate of 1 / 3. The error correction decoder is also called an error correction decoder.

[0164] In this way, the wireless communication system in the third embodiment transmits command data that has been error correction coded in error correction coding section 204, and therefore a coding gain is obtained through error correction, and as a result, the threshold value STH can be lowered. For example, even if the SINR at the time of demodulating the command signal is reduced due to strong interference waves and the demodulated command data is erroneous, the communication quality of the command signal can be ensured because the SINR is corrected by the error correction decoder 111. In this case, the threshold value STH can be lowered to an extremely low SINR at which the error correction decoder 111 cannot correct the erroneous data.

[0165] Therefore, compared to the first embodiment, the wireless communication system in this embodiment can maintain the communication quality of the command signal without going into interference avoidance operation even under conditions of a lower SINR. The communication method determination unit 106 may add reliability information from the error correction decoding unit 111 to the determination of switching the center frequency and modulation method of the command signal.

[0166] Embodiment 4 In this embodiment, differences from the first to third embodiments and additional features to the first to third embodiments will be mainly described. In this embodiment, components having the same functions as those in the first to third embodiments are given the same reference numerals, and the description thereof will be omitted.

[0167] In the first to third embodiments, an example has been described in which an interference wave overlaps with a command signal transmitted from the ground station 04 to the terminal station 01. In the present embodiment, a mode will be described in which, conversely, even if an interference wave overlaps with a telemetry signal transmitted from the terminal station 01 to the ground station 04, the communication quality of the telemetry signal can be maintained in a similar manner. In this case, the configuration in FIG. 2 serves as a ground station, receives telemetry data instead of command data, and the telemetry transmitter 110 is replaced with a command transmitter. Also, the configuration in FIG. 3 serves as a terminal station, receives telemetry data instead of command data, and the telemetry receiver 200 is replaced with a command receiver.

[0168] Furthermore, in the case where an interference wave overlaps with the command signal transmitted from the ground station 04 to the terminal station 01 and also overlaps with the telemetry signal transmitted from the terminal station 01 to the ground station 04, the interference avoidance means and interference suppression means shown in the present embodiments 1 to 3 are provided on both the uplink and downlink.

[0169] FIG. 24 is a diagram showing an example of the configuration of a wireless communication system according to the present embodiment. 24 differs from the first embodiment in that an interference source 11 is added. An interference wave 12 from the interference source 11 interferes with a telemetry signal transmitted from the terminal station 01 to the ground station 04. When the telemetry signal is affected by interference from the interference source 11, the ground station 04 cannot normally receive the modulation method and center frequency information designated by the communication method determination unit 106 of the terminal station 01. As a result, the ground station 04 cannot detect which modulation method to use for modulating the command data and which center frequency to use for transmission, and falls into a state where it cannot transmit the command signal.

[0170] FIG. 25 is a diagram showing an example of the configuration of the terminal station 01 according to the present embodiment. FIG. 26 is a diagram showing an example of the configuration of the ground station 04 according to this embodiment. In this embodiment, the terminal station 01 has the configuration shown in FIG. 25, and the ground station 04 has the configuration shown in FIG. 26, thereby making it possible to avoid interference with not only command signals but also telemetry signals. The terminal station 01 of this embodiment shown in FIG. 25 differs from the terminal station 01 of the first embodiment shown in FIG. 2 in that the telemetry transmission unit 110 is replaced with a telemetry transmission unit 110a. The difference between the ground station 04 of this embodiment shown in FIG. 26 and the ground station 04 of the first embodiment shown in FIG. 3 is that the telemetry receiving unit 200 is replaced with a telemetry receiving unit 200a.

[0171] The configuration of the telemetry transmission unit 110a is similar to the configuration of the command data transmission unit 205 indicated by the dotted line frame in Fig. 26. The difference between the telemetry transmission unit 110a and the command data transmission unit 205 is that the telemetry transmission unit 110a makes one or more copies of telemetry data instead of command data, modulates the copies in one or more modulation units, and transmits the copies. The telemetry receiver 200a has the same configuration as the command data receiver 112 shown in the line frame in FIG. 25. The telemetry receiver 200a is different from the command data receiver 112 in that the communication method determination unit 106 of the ground station 04 determines each modulation method and each center frequency information of the telemetry signal based on the reception power spectrum information of the downlink, not the uplink. Each demodulator of the telemetry receiver 200a demodulates the telemetry signal, not the command signal, and the synthesizer outputs the demodulated telemetry signals synthesized as telemetry data. Although not shown, the telemetry receiver 200a extracts modulation method information (Mod Type#1 to #3) and center frequency information (Fc#1 to #3) to be given to each modulator of the ground station 04 from the obtained telemetry data, and notifies each modulator (202a, 202b, 202c). In addition, the communication method determination unit 106 implemented in the telemetry receiving unit 200a of the ground station 04 may also be configured using software, and may be realized using artificial intelligence (AI) that determines an appropriate center frequency and modulation method for the telemetry signal while learning from machine learning the interference that changes dynamically in the two dimensions of frequency and time.

[0172] FIG. 27 is a flow diagram showing an operation related to a telemetry line in wireless communication system 500 according to the present embodiment. FIG. 25 shows an operational flow regarding the telemetry line. Steps S11 to S13 are operations performed on the terminal station side, and steps S14 to S16 are operations performed on the ground station side.

[0173] The operation flow for the telemetry line in Fig. 27 has the same design concept as the operation flow for the command line explained in Fig. 4 of the first embodiment. The difference from the design concept of the first embodiment is that the terminal station 01 transmits a telemetry signal at the default downlink frequency and modulation method only when the terminal station 01 does not receive a command signal for a certain period of time, such as immediately after starting operation. The reason for this control is that immediately after the start of operation, the ground station 04 has not yet communicated the center frequency and appropriate modulation method of the telemetry signal to the terminal station 01 by a command signal. In this state, the ground station 04 needs to receive the telemetry signal from the terminal station 01, so only immediately after the start of operation, the center frequency and modulation method of the telemetry signal transmitted from the terminal station 01 to the ground station 04 use predetermined default values. The default downlink frequency and modulation method are also known to the ground station 04, so the ground station 04 is able to receive the telemetry signal.

[0174] The default downlink frequency and modulation method may be changed every time, instead of being fixed. In this case, the ground station 04 can receive the telemetry signal if it holds the change pattern of the downlink frequency and modulation method for this time as known information in advance. In this way, by changing the default downlink frequency and modulation method every time, instead of fixing them, the ability to avoid interference with the telemetry signal immediately after the start of operation is improved.

[0175] In addition, not only immediately after the start of operation but also during operation, the terminal station 01 may transmit a telemetry signal modulated based on the frequency and modulation method of the telemetry signal determined by the ground station 04, while simultaneously transmitting the same telemetry signal modulated with the default downlink frequency and modulation method. In this case, the ground station 04 demodulates these two telemetry modulated signals, combines them, and receives the telemetry signal. Using such frequency diversity improves the interference resistance performance on the downlink side and realizes reliable reception of the telemetry signal at the ground station.

[0176] With the above-described configuration and operation flow, in the wireless communication system according to this embodiment, the ground station 04 determines the center frequency and appropriate modulation method of the telemetry signal that realizes an appropriate reception SINR based on the downlink reception power spectrum. Then, the terminal station transmits the telemetry signal based on the frequency and modulation method of the telemetry signal determined by the ground station. These operations of the ground station and the terminal station are repeated. As a result, the wireless communication system according to this embodiment is provided with interference avoidance means and interference suppression means for both the command line on the uplink side and the telemetry line on the downlink side, making it possible to realize a wireless communication system with even better interference resistance than the first embodiment.

[0177] In the above first to fourth embodiments, each unit of each device of the wireless communication system 500 has been described as an independent functional block. However, the configuration of each device of the wireless communication system 500 does not have to be the configuration as in the above-mentioned embodiments. The functional blocks of each device of the wireless communication system 500 may have any configuration as long as they can realize the functions described in the above-mentioned embodiments. Furthermore, each device of the wireless communication system 500 does not have to be a single device, and may be a system composed of multiple devices. In addition, it is possible to combine two or more parts of the first to fourth embodiments. Alternatively, it is possible to implement only one part of these embodiments. In addition, it is possible to implement any combination of these embodiments, either as a whole or in part. That is, in the first to fourth embodiments, the embodiments can be freely combined, any of the components in each embodiment can be modified, or any of the components in each embodiment can be omitted.

[0178] The above-described embodiment is essentially a preferred example, and is not intended to limit the scope of the present disclosure, the scope of application of the present disclosure, and the scope of use of the present disclosure. The above-described embodiment can be modified in various ways as necessary. For example, the procedure described using a flow chart or sequence chart may be modified as appropriate.

[0179] Various aspects of the present disclosure are summarized below as appendices.

[0180] (Appendix 1) A wireless communication system including a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, The terminal station, a spectrum measurement unit that measures a power spectrum of a received signal as a received spectrum; an interference wave detection unit that detects a signal band in which an interference wave exists from the reception spectrum by using a threshold value as interference wave detection information; a communication method determination unit that determines a center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and SINR (signal power to interference plus noise power ratio) measured by N demodulation units; The N demodulation units wait for a command signal for each of the center frequencies of the N channels, and when a command signal is received, demodulate the command signal and transmit the SINR to the communication method determination unit; a synthesis unit that synthesizes the N command signals demodulated by the N demodulation units and outputs the synthesized signal as command data; a telemetry transmitting unit that transmits the center frequencies for the N channels to the ground station as a telemetry signal; A wireless communication system comprising: (Appendix 2) The ground station: a telemetry receiving unit that receives the telemetry signal and extracts center frequencies for the N channels included in the telemetry signal; a data duplicating unit for duplicating command data to be transmitted to the terminal station into N pieces; N modulation units that modulate and frequency convert each of the N pieces of copied command data based on a center frequency for the N channels and output the converted data as the command signal; 2. A wireless communication system as described in claim 1, comprising: (Appendix 3) In the terminal station, The communication method determination unit determining a center frequency for the N channels and determining a modulation method for a command signal for each of the N channels from M types (where M∈{2, 3, ..}); The demodulation unit is demodulate each of the N channels of command signals using the modulation method for each of the N channels; The telemetry transmission unit is 3. The wireless communication system of claim 2, wherein the center frequency of each of the N channels as well as the modulation scheme of each of the N channels are transmitted to the ground station as a telemetry signal. (Appendix 4) In the ground station, The telemetry receiving unit includes: extracting information on a center frequency of each of the N channels and a modulation method of each of the N channels from a telemetry signal transmitted from the terminal station; The N modulation units include 4. The wireless communication system according to claim 3, wherein each of the N duplicated command data is modulated using a modulation method for each of the N channels, and then transmitted to the terminal station using a center frequency for each of the N channels. (Appendix 5) The terminal station, 5. The wireless communication system according to claim 1, further comprising an interference suppression unit that suppresses an interference wave superimposed on a command signal based on reception level information of the interference wave detected by the interference detection unit, and provides the command signal after interference suppression to the N demodulation units. (Appendix 6) The communication method determination unit 6. The wireless communication system according to claim 1, wherein the threshold value is determined using noise power information measured in advance before operation. (Appendix 7) The communication method determination unit 7. The wireless communication system according to claim 1, wherein when a command signal is not received, the SINR is calculated using an expected reception level of the command signal, rather than a value measured by the demodulation unit. (Appendix 8) 5. The wireless communication system according to claim 3, wherein the number of channels N is 2 or more, and the modulation methods include a direct sequence spread spectrum (DSS) method and a narrowband modulation method. (Appendix 9) 9. The wireless communication system according to claim 8, wherein the terminal station transmits a spectrum of a narrowband modulation scheme and a spectrum of a direct sequence spread spectrum (DSS) in a state where the spectrum is overlapped on the frequency axis. (Appendix 10) 5. The wireless communication system according to claim 3, wherein the number of channels N is 2 or more, and the modulation method includes a direct sequence spread spectrum (DSS) method and a frequency hopping (FH) method. (Appendix 11) The wireless communication system according to claim 10, wherein the terminal station transmits a frequency hopping (FH) spectrum and a direct sequence spread spectrum (DSS) in a state where the spectrum is overlapped on the frequency axis. (Appendix 12) The communication method determination unit further determines a parameter related to a time of the command signal; the demodulation unit demodulates each of the command signals for N channels using the time-related parameters determined by the communication method determination unit; The telemetry transmission unit also transmits parameter information related to the time determined by the communication method determination unit to the ground station in a telemetry signal; In the ground station, The telemetry receiving unit includes: extracting parameter information relating to the time transmitted by the telemetry transmitter; The N modulation units include 5. The wireless communication system according to claim 3 or 4, wherein each of the N pieces of copied command data is modulated using the parameter information related to time extracted by the telemetry receiving unit, and then transmitted to the terminal station at a frequency of command signals for N channels. (Appendix 13) the number of channels N is 2 or more, and the combining unit of the terminal station is configured with an error correction decoder; 3. The wireless communication system of claim 2, wherein the data replicating unit of the ground station is configured with an error correction coder. (Appendix 14) The telemetry receiving unit in the ground station a telemetry spectrum measurement unit that measures a spectrum of a telemetry reception signal; a telemetry interference wave detection unit that detects a signal band in which an interference wave exists and a reception level of the interference wave from the telemetry reception spectrum measured by the telemetry spectrum measurement unit; a telemetry communication method determination unit that determines the frequency of the telemetry signal for N' channels (where N'∈{1, 2, 3...}) based on the result detected by the telemetry interference wave detection unit and the demodulation states of the N' telemetry demodulation units; the N' telemetry demodulation units that wait for a telemetry signal for each of the N' channel frequencies determined by the telemetry communication method determination unit and demodulate the telemetry signal when the telemetry signal is captured; a telemetry synthesis unit that synthesizes the N' telemetry signals demodulated by the N' demodulation units and outputs the synthesized signal as telemetry data; the ground station includes a command transmission unit that transmits the telemetry center frequencies for the N' channels determined by the telemetry communication method determination unit as command signals to the terminal station; The telemetry transmission unit in the terminal station 3. A wireless communication system as described in claim 2, comprising: a data duplicating unit that duplicates telemetry data into N' pieces; and N' modulators that modulate and frequency convert the N' duplicated pieces of telemetry data based on a center frequency of the N' channels of telemetry signals, and output the resulting signals as the telemetry signals. (Appendix 15) In the ground station, the telemetry communication method determination unit determines a frequency of a telemetry signal to N' channels (where N'∈{2, 3, 4...}) and at the same time determines a modulation method of the telemetry signal suitable for each channel from among M types (where M∈{2, 3, ..}); the telemetry demodulation unit demodulates each of the telemetry signals of the N' channels by the modulation method determined by the telemetry communication method determination unit; the command transmitting unit transmits, to the terminal station, in a command signal, information on a modulation method suitable for each channel in addition to the center frequencies of the telemetry signals for the N' channels determined by the telemetry communication method determining unit; The terminal station, demodulating the command signal to extract a center frequency of the command signal for N' channels and information on a modulation method suitable for each channel; The telemetry transmission unit is 15. The wireless communication system according to claim 14, wherein telemetry signals for N' channels are modulated and transmitted based on the extracted information on a modulation method suitable for each channel. (Appendix 16) A wireless communication method for use in a wireless communication system comprising a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, The terminal station, Measure the power spectrum of the received signal as a received spectrum; Detecting a signal band in which an interference wave exists from the received spectrum using a threshold value as interference wave detection information; determining a center frequency of the command signal for N channels (N is a natural number) based on the interference detection information and a measured SINR (signal to interference plus noise ratio); A command signal is waited for for each of the center frequencies of the N channels, and when a command signal is received, the command signal is demodulated; Combining the demodulated N command signals and outputting the combined signal as command data; A wireless communication method for transmitting the center frequencies for the N channels as telemetry signals to the ground station. (Appendix 17) A wireless communication program for use in a wireless communication system including a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, A spectrum measurement process for measuring a power spectrum of a received signal as a received spectrum; an interference wave detection process for detecting a signal band in which an interference wave exists from the received spectrum using a threshold value as interference wave detection information; A communication method determination process for determining a center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and a measured SINR (signal power to interference plus noise power ratio); a demodulation process for waiting for a command signal for each of the N channel frequencies and demodulating the command signal when the command signal is received; a synthesis process of synthesizing the adjusted N command signals and outputting the synthesized signal as command data; a telemetry transmission process for transmitting the center frequencies of the N channels as a telemetry signal to the ground station; A wireless communication program that causes a computer to execute the above. (Appendix 18) The wireless communication program according to claim 17, wherein the communication method determination process is implemented by artificial intelligence based on machine learning. (Appendix 19) The wireless communication system according to any one of claims 1 to 4, wherein the communication method determination unit is configured with artificial intelligence based on machine learning. [Explanation of symbols]

[0181] 01 terminal station, 02, 05 receiving antenna, 03, 06 transmitting antenna, 07 command signal, 04 ground station, 08 telemetry signal, 09 interference source, 10 interference wave, 11 interference source, 99 amplifier, 100 receiving filter, 101 variable gain section, 102 automatic gain control section, 103 AD converter, 104 spectrum measurement section, 105 interference wave detection section, 106 communication method determination section, 107 interference suppression section, 108 demodulation section, 109 synthesis section, 110, 110a telemetry transmission section, 111 error correction decoding section, 112 command data reception section, 200, 200a telemetry reception section, 201 data duplication section, 202 modulation section, 203 synthesis section, 204 error correction coding section, 205 command data transmission section, 301 timing control section, 302, 303 Hanning window addition unit, 401 weighting conversion unit, 402, 403 delay unit, 404, 405 multiplier, 500 wireless communication system, 909 electronic circuit, 910 processor, 921 memory, 922 auxiliary storage device, 930 input / output interface, 950 communication interface.

Claims

1. A wireless communication system including a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, The terminal station, a spectrum measurement unit that measures a power spectrum of a received signal as a received spectrum; an interference wave detection unit that detects a signal band in which an interference wave exists from the reception spectrum by using a threshold value as interference wave detection information; a communication method determination unit that determines a center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and SINRs (signal power to interference plus noise power ratios) measured by the N demodulation units; the N demodulation units each waiting for a command signal for each of the center frequencies of the N channels, and demodulating the command signal when receiving the command signal, and at the same time transmitting the SINR to the communication method determination unit; a synthesis unit that synthesizes the N command signals demodulated by the N demodulation units and outputs the synthesized signal as command data; a telemetry transmitting unit that transmits the center frequencies of the N channels to the ground station as telemetry signals; A wireless communication system comprising:

2. The ground station: a telemetry receiving unit that receives the telemetry signal and extracts center frequencies for the N channels included in the telemetry signal; a data duplicating unit for duplicating command data to be transmitted to the terminal station into N pieces; N modulation units that modulate and frequency-convert each of the N pieces of copied command data based on a center frequency for the N channels and output the result as the command signal; The wireless communication system according to claim 1 .

3. In the terminal station, The communication method determination unit determining a center frequency for the N channels and determining a modulation method for a command signal for each of the N channels from M types (where M ∈ {2, 3, . . .}); The demodulation unit is demodulating the command signals for each of the N channels using a modulation method for each of the N channels; The telemetry transmission unit is 3. The wireless communication system according to claim 2, wherein the center frequency of each of said N channels as well as the modulation scheme of each of said N channels are transmitted to said ground station in a telemetry signal.

4. In the ground station, The telemetry receiving unit includes: extracting information on a center frequency of each of the N channels and a modulation method of each of the N channels from a telemetry signal transmitted from the terminal station; The N modulation units include 4. The wireless communication system according to claim 3, wherein each of the N pieces of copied command data is modulated using a modulation method for each of the N channels, and then transmitted to the terminal station using a center frequency for each of the N channels.

5. The terminal station, 5. The wireless communication system according to claim 1, further comprising an interference suppression unit that suppresses interference waves superimposed on a command signal based on reception level information of the interference waves detected by the interference wave detection unit, and provides the command signal after interference suppression to the N demodulation units.

6. The communication method determination unit 5. The wireless communication system according to claim 1, wherein the threshold value is determined by using noise power information measured beforehand before operation.

7. The communication method determination unit 5. The wireless communication system according to claim 1, wherein when a command signal is not being received, the SINR is calculated using an expected reception level of the command signal, rather than a value measured by the demodulator.

8. 5. The wireless communication system according to claim 3, wherein the number of channels N is 2 or more, and modulation methods include a direct sequence spread spectrum (DSS) method and a narrowband modulation method.

9. 9. The wireless communication system according to claim 8, wherein the terminal station transmits a narrowband modulation spectrum and a direct sequence spread spectrum (DSS) in a state where the spectrum is overlapped on the frequency axis.

10. 5. The wireless communication system according to claim 3, wherein the number of channels N is 2 or more, and modulation methods include a direct sequence spread spectrum (DSS) method and a frequency hopping (FH) method.

11. 11. The wireless communication system according to claim 10, wherein the terminal station transmits a frequency hopping (FH) spectrum and a direct sequence spread spectrum (DSS) in a state where the spectrum is overlapped on the frequency axis.

12. The communication method determination unit further determines a parameter related to a time of the command signal, the demodulation unit demodulates each of the command signals for N channels using the time-related parameters determined by the communication method determination unit; The telemetry transmission unit also transmits parameter information related to the time determined by the communication method determination unit to the ground station in a telemetry signal; In the ground station, The telemetry receiving unit includes: extracting parameter information relating to the time transmitted by the telemetry transmitter; The N modulation units include 5. The wireless communication system according to claim 3, wherein each of the N pieces of copied command data is modulated using the parameter information related to time extracted by the telemetry receiving unit, and then transmitted to the terminal station at a frequency of the command signal for N channels.

13. the number of channels N is 2 or more, and the combining unit of the terminal station is composed of an error correction decoder; 3. The wireless communication system according to claim 2, wherein the data replicating unit of the ground station is constituted by an error correction encoder.

14. The telemetry receiving unit in the ground station a telemetry spectrum measurement unit that measures a spectrum of a telemetry reception signal; a telemetry interference wave detection unit that detects a signal band in which an interference wave exists and a reception level of the interference wave from the telemetry reception spectrum measured by the telemetry spectrum measurement unit; a telemetry communication method determination unit that determines the frequency of the telemetry signal for N' channels (where N'∈{1, 2, 3 . . .}) based on the result detected by the telemetry interference wave detection unit and the demodulation states of the N' telemetry demodulation units; the N' telemetry demodulation units which wait for a telemetry signal for each of the N' channel frequencies determined by the telemetry communication method determination unit and demodulate the telemetry signal when the telemetry signal is captured; a telemetry synthesis unit that synthesizes the N' telemetry signals demodulated by the N' demodulation units and outputs the synthesized signal as telemetry data; the ground station includes a command transmission unit that transmits the telemetry center frequencies for the N' channels determined by the telemetry communication method determination unit as command signals to the terminal station; The telemetry transmission unit in the terminal station 3. The wireless communication system according to claim 2, comprising a data duplicating unit which duplicates telemetry data into N' pieces, and N' modulators which modulate and frequency convert the N' pieces of telemetry data based on the center frequency of the N' channels of telemetry signals, and output them as the telemetry signals.

15. In the ground station, the telemetry communication method determination unit determines a frequency of a telemetry signal on N' channels (where N'∈{2, 3, 4, ..}) and at the same time determines a modulation method of the telemetry signal suitable for each channel from among M types (where M∈{2, 3, ..}); the telemetry demodulation unit demodulates each of the telemetry signals of the N' channels by the modulation method determined by the telemetry communication method determination unit; the command transmission unit transmits, to the terminal station, in a command signal, information on a modulation method suitable for each channel in addition to the center frequencies of the telemetry signals for the N' channels determined by the telemetry communication method determination unit; The terminal station, demodulating the command signal to extract a center frequency of the command signal for N' channels and information on a modulation method suitable for each channel; The telemetry transmission unit is 15. The wireless communication system according to claim 14, wherein telemetry signals for N' channels are modulated and transmitted based on the extracted information on a modulation method suitable for each of said channels.

16. A wireless communication method for use in a wireless communication system comprising a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, The terminal station, Measure the power spectrum of the received signal as a received spectrum; Detecting a signal band in which an interference wave exists from the received spectrum using a threshold value as interference wave detection information; determining a center frequency of the command signal for N channels (N is a natural number) based on the interference detection information and a measured SINR (signal to interference plus noise ratio); Awaiting a command signal for each of the center frequencies of the N channels, and demodulating the command signal when the command signal is received; Combining the demodulated N command signals and outputting the combined signal as command data; A wireless communication method for transmitting the center frequencies of the N channels as telemetry signals to the ground station.

17. A wireless communication program for use in a wireless communication system including a terminal station and a ground station for transmitting a command signal to the terminal station, the terminal station transmitting a telemetry signal to the ground station, A spectrum measurement process for measuring a power spectrum of a received signal as a received spectrum; an interference wave detection process for detecting a signal band in which an interference wave exists from the received spectrum using a threshold value as interference wave detection information; a communication method determination process for determining a center frequency of the command signal for N channels (N is a natural number) based on the interference wave detection information and a measured SINR (signal power to interference plus noise power ratio); a demodulation process for waiting for a command signal for each of the N channel frequencies and demodulating the command signal when the command signal is received; a synthesis process of synthesizing the adjusted N command signals and outputting the synthesized signal as command data; a telemetry transmission process of transmitting the center frequencies of the N channels as a telemetry signal to the ground station; A wireless communication program that causes a computer to execute the above.

18. The wireless communication program according to claim 17 , wherein the communication method determination process is implemented by artificial intelligence based on machine learning.

19. The wireless communication system according to claim 1 , wherein the communication method determination unit is configured with artificial intelligence based on machine learning.

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