Control station

Abstract

The present disclosure relates to a control station. This control station is notified, from a reception device that aerially receives radio waves transmitted by a transmission device, regarding the reception level of the radio waves, the control station being configured to execute: a process for holding the ideal characteristics of an antenna of the reception device, and identifying information pertaining to radio waves transmitted by the transmission device; a process for receiving a plurality of reception levels from the reception device; a process for identifying the generation frequencies of each of the plurality of reception levels; a process for correcting the ideal characteristics so as to match a plurality of sets of the reception levels and the generation frequencies, thereby generating correction characteristics; and a process for determining, as a communication frequency, the frequency at which the reception level is maximized in the correction characteristics.

Description

Control Station

[0001] The present disclosure relates to a control station.

[0002] In a small aircraft equipped with a wireless communication device that is composed of a transmitter and a receiver and can freely set the communication frequency, there is a demand for improving the reception level of the receiver in wireless communication in the sky. For example, Patent Document 1 discloses a technology for improving the radiation efficiency of wireless communication using an antenna by changing the communication frequency. In other words, by optimizing the communication frequency, the reception level in wireless communication can be increased.

[0003] One method for optimizing the communication frequency used for wireless communication in the sky is to measure the reception level beforehand using a small aircraft before flight. For example, the communication frequency can be optimized by transmitting radio waves of a specific frequency while the small aircraft is placed on the ground and measuring the reception level.

[0004] Patent No. 7210606

[0005] However, with the above-mentioned method, errors in antenna characteristics, such as VSWR (Voltage Standing Wave Ratio), occur due to the influence of the ground. These errors tend to be particularly large at low frequencies. As a result, when wireless communication using the optimized communication frequency is performed in the air, the antenna's radiation efficiency decreases, resulting in a problem of reduced reception levels.

[0006] In order to solve the above-mentioned problems, the present disclosure aims to provide a control station that can improve the reception level and realize efficient communication in wireless communication in the sky.

[0007] An aspect of the present disclosure is a control station that is notified of the reception level of radio waves from a receiving device that receives radio waves transmitted from a transmitting device in the sky, and is preferably configured to maintain ideal characteristics of the antenna of the receiving device and perform the following processes: a process of specifying information about the radio waves transmitted by the transmitting device; a process of receiving multiple reception levels from the receiving device; a process of identifying a generation frequency for each of the multiple reception levels; a process of generating correction characteristics by correcting the ideal characteristics to be consistent with multiple sets of reception levels and generation frequencies; and a process of determining the frequency at which the reception level is maximum in the correction characteristics as the communication frequency.

[0008] According to aspects of the present disclosure, it is possible to improve reception levels and achieve efficient communication in wireless communication in the sky.

[0009] 1 is a diagram illustrating a method for optimizing a communication frequency according to a comparative example. FIG. 2 is a diagram illustrating a wireless communication system according to a first embodiment of the present disclosure. FIG. 3 is a block diagram illustrating a configuration of a control station according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of a hardware configuration of a control station according to the first embodiment of the present disclosure. FIG. 5 is a block diagram illustrating a configuration of a transmission device according to the first embodiment of the present disclosure. FIG. 6 is a block diagram illustrating a configuration of a reception device according to the first embodiment of the present disclosure. FIG. 7 is a block diagram illustrating a configuration of a radio wave receiving unit according to the first embodiment of the present disclosure. FIG. 8 is a graph illustrating an example of a measurement result of a reception level when the radio wave receiving unit according to the first embodiment of the present disclosure has a low-pass filter. FIG. 9 is a graph illustrating an example of a measurement result of a reception level when the radio wave receiving unit according to the first embodiment of the present disclosure does not have a low-pass filter. FIG. 10 is a flowchart illustrating a process performed by a wireless communication system according to the first embodiment of the present disclosure. FIG. 11 is a flowchart illustrating a process performed by a wireless communication system according to the second embodiment of the present disclosure. FIG. 12 is a graph illustrating a method for determining a communication frequency according to the second embodiment of the present disclosure. FIG. 13 is a graph illustrating ideal characteristics of an antenna according to the second embodiment of the present disclosure. FIG. 14 is a graph illustrating actual characteristics in the sky of an antenna according to the second embodiment of the present disclosure. FIG. 15 is a table illustrating ideal characteristics of an antenna according to the second embodiment of the present disclosure. FIG. 16 is a table illustrating actual characteristics in the sky of an antenna according to the second embodiment of the present disclosure. 1 is a first flowchart showing a first curve fitting process according to a second embodiment of the present disclosure; FIG. 2 is a second flowchart showing a first curve fitting process according to the second embodiment of the present disclosure; FIG. 3 is a third flowchart showing a first curve fitting process according to the second embodiment of the present disclosure; FIG. 4 is a diagram showing a specific example of loop 1 of the first curve fitting process according to the second embodiment of the present disclosure; FIG. 5 is a diagram showing a specific example of loop 2 of the first curve fitting process according to the second embodiment of the present disclosure; FIG. 6 is a graph showing a first method of determining candidate communication frequencies of the first curve fitting process according to the second embodiment of the present disclosure; FIG. 7 is a graph showing a second method of determining candidate communication frequencies of the first curve fitting process according to the second embodiment of the present disclosure;10 is a graph illustrating a third curve fitting according to the second embodiment of the present disclosure.

[0010] First Embodiment Before describing this embodiment, a comparative example will be described. Fig. 1 is a diagram showing a method for optimizing a communication frequency according to the comparative example.

[0011] In the comparative example, the communication frequency is adjusted and optimized to increase the reception level in the sky of the receiving device 6. The receiving device 6 is a small flying object, in this case a drone, equipped with a wireless communication device. The reception level of the receiving device 6 is measured using a measuring instrument 8 connected to the receiving device 6.

[0012] The reception level of the receiving device 6 according to this comparative example is measured with the receiving device 6 placed on the ground 10. Therefore, an error occurs between the antenna characteristics and the values ​​in the sky due to the influence of the ground. This error tends to be particularly large when the frequency is low. As a result, when wireless communication using an optimized communication frequency is performed in the sky, the antenna radiation efficiency decreases, resulting in a problem of a decrease in reception level. The present disclosure solves this problem.

[0013] 2 is a diagram illustrating a wireless communication system according to the first embodiment of the present disclosure. The optimization method according to this embodiment differs from the comparative example in that a receiving device that measures the reception level is located in the sky. Note that the receiving device 6 according to this embodiment is capable of detecting the frequency of the received radio wave.

[0014] The wireless communication system 100 includes a control station 2. The control station 2 transmits a control signal to a transmission device 4 and specifies information on radio waves to be transmitted by the transmission device 4. The transmission device 4 is a small aircraft, which is a drone in this example, equipped with a wireless communication device.

[0015] The information on the radio waves to be transmitted may be, for example, a specific frequency, a profile showing changes in frequency over time, or a frequency that changes over time according to the profile. The profile showing changes in frequency over time is information defined by, for example, a specified frequency width and sweep time. The frequency that changes over time according to the profile is, for example, multiple specific frequency values ​​that change by a specific frequency width for each specific sweep time.

[0016] The transmitting device 4 transmits radio waves of a specified frequency to the receiving device 6 located in the sky. The receiving device 6 is a small flying object equipped with a wireless communication device, and is a drone in this example. Note that although the transmitting device 4 is shown here as being located in the sky, it may also be placed on the ground 10.

[0017] The receiving device 6 receives in the sky the radio waves transmitted by the transmitting device 4 and detects the reception level of the received radio waves. The receiving device 6 also notifies the control station 2 of the detected radio wave reception level. The receiving device 6 also detects the frequency of the radio waves when the reception level is detected and notifies the control station 2 of the same.

[0018] 3 is a block diagram showing the configuration of a control station according to the first embodiment of the present disclosure. First, a procedure when the control station 2 transmits an instruction to the transmitting device 4 or the receiving device 6 will be described.

[0019] The control station 2 includes an input / output unit 21. The input / output unit 21 transmits input control information to a control unit 22. The control information may be, for example, information about radio waves transmitted by the transmitting device 4, or information about the time when the receiving device 6 receives radio waves. The control information may also be directly input by, for example, a measurer.

[0020] The control unit 22 transmits the input control information to the display unit 23. The display unit 23 displays the received control information. By visually checking this display, the measurer can confirm the control information, including the frequency of the radio waves transmitted by the transmitter 4.

[0021] The control unit 22 also transmits the input control information to the radio unit 24. The radio unit 24 converts the input control information into a control signal and transmits it to the antenna unit 25. The antenna unit 25 transmits the received control signal to the transmitting device 4.

[0022] Next, a procedure will be described for the control station 2 to receive a notification from the receiving device 6. The antenna unit 25 receives a notification signal including notification information from the receiving device 6 and transmits it to the radio unit 24. The radio unit 24 converts the notification signal into notification information and transmits it to the control unit 22.

[0023] The control unit 22 transmits the notification information to the display unit 23. The display unit 23 displays the received notification information. By visually checking this display, the person measuring can confirm the notification information including the reception level of the radio waves received by the receiving device 6.

[0024] Furthermore, the control unit 22 transmits the notification information to the input / output unit 21. The input / output unit 21 outputs the notification information. For example, the input / output unit 21 may output the notification information to a computer so that the computer can store the reception level and the frequency in association with each other.

[0025] 4 is a diagram illustrating an example of a hardware configuration of a control station according to the first embodiment of the present disclosure. Each function of the control station 2 may be partially or entirely configured by hardware such as a programmable logic device (PLD) or a field programmable gate array (FPGA), or may be configured as a program executed by a processor such as a CPU.

[0026] For example, the control station 2 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0027] 4, the control station 2 has an input unit 200, an output unit 201, a communication unit 202, a CPU 203, a memory 204, and an HDD 205 connected via a bus 206, and functions as a computer. The control station 2 is also capable of inputting and outputting data to and from a computer-readable storage medium 207.

[0028] The input unit 200 is, for example, a keyboard and a mouse, etc. The output unit 201 is, for example, a display device such as a display.

[0029] The communication unit 202 is, for example, a communication interface that communicates with a wireless device to be controlled.

[0030] The CPU 203 controls each component of the control station 2 and performs predetermined processing, etc. The memory 204 and HDD 205 store data, etc.

[0031] The storage medium 207 is capable of storing programs and the like that cause the control station 2 to execute the functions of the control station 2. Note that the architecture that configures the control station 2 is not limited to the example shown in FIG.

[0032] 5 is a block diagram showing the configuration of a transmission device according to the first embodiment of the present disclosure. First, a procedure in which the transmission device 4 transmits radio waves to the reception device 6 in accordance with an instruction from the control station 2 will be described.

[0033] The transmitting device 4 includes an antenna unit 41. The antenna unit 41 is an antenna used when the transmitting device 4 communicates wirelessly with the control station 2. The antenna unit 41 receives a control signal from the control station 2 and transmits it to a wireless unit 42.

[0034] The radio unit 42 converts the received control signal into control information and transmits it to the control unit 43. The control unit 43 transmits to the radio wave transmitting unit 44 information for transmitting radio waves at the frequency included in the received control information.

[0035] The radio wave transmitting unit 44 transmits a radio wave transmission instruction based on the received information to the antenna unit 45. The antenna unit 45 is an antenna used when the transmitting device 4 transmits radio waves to the receiving device 6. The antenna unit 45 transmits radio waves to the receiving device 6 based on the transmission instruction. This radio wave is transmitted at a frequency specified by the control station 2.

[0036] Next, a procedure will be described for when the transmitting device 4 transmits notification information to the control station 2. This information transmission is performed, for example, when the transmitting device 4 is unable to transmit radio waves due to a malfunction, in order to notify the control station 2 of this information.

[0037] When radio wave transmission unit 44 is unable to transmit radio waves, it transmits information to control unit 43. Control unit 43 transmits the received information to wireless unit 42. Alternatively, control unit 43 may add information required to identify the cause of the malfunction to the information transmitted to wireless unit 42. The information required here is, for example, weather information such as the reception level, temperature, or humidity at the time of the malfunction.

[0038] The radio unit 42 converts the received information into a notification signal and transmits it to the antenna unit 41. The antenna unit 41 transmits the received notification signal to the control station 2.

[0039] The antenna unit 41, the wireless unit 42, the control unit 43, the radio wave transmitting unit 44, and the antenna unit 45 are mounted on a small mobile body 46. In this example, the small mobile body 46 is a drone.

[0040] 6 is a block diagram showing the configuration of a receiving device according to the first embodiment of the present disclosure. First, a procedure in which the receiving device 6 transmits the reception level of the radio wave received from the transmitting device 4 to the control station 2 will be described.

[0041] The receiving device 6 includes an antenna unit 65. The antenna unit 65 is an antenna used to receive radio waves from the transmitting device 4. The antenna unit 65 receives radio waves from the transmitting device 4 and transmits them to the radio wave receiving unit 64.

[0042] The radio wave receiving unit 64 measures the reception level and time of the received radio waves and transmits them to the control unit 63. The control unit 63 transmits notification information including the reception level of the received radio waves to the wireless unit 62. The time may be synchronized in advance between the transmitting device, the receiving device, and the control station, or the control station may obtain the time difference between the transmitting device and the receiving device.

[0043] The radio unit 62 converts the received notification information into a notification signal and transmits it to the antenna unit 61. The antenna unit 61 is an antenna used when the receiving device 6 communicates wirelessly with the control station 2. The antenna unit 61 transmits the received notification signal to the control station 2.

[0044] Next, the procedure when the receiving device 6 receives control information from the control station 2 will be explained. This information reception is performed in order for the control station 2 to receive control information including information necessary for control when controlling the receiving device 6. The information necessary for control is, for example, information related to measurement of the reception level or information related to the frequency. The information related to measurement of the reception level is, for example, the time period or length of time when radio waves should be received. The information related to the frequency is, for example, the frequency designated by the control station 2 as the reception frequency.

[0045] The antenna unit 61 receives a control signal from the control station 2 and transmits it to the radio unit 62. The radio unit 62 converts the received control signal into control information and transmits it to the control unit 63. The control unit 63 transmits the control information, which includes information related to the measurement of the reception level, to the radio wave receiving unit 64.

[0046] The radio wave receiving unit 64 measures the reception level of the received radio wave based on the information relating to the measurement of the reception level.

[0047] The antenna unit 61, the wireless unit 62, the control unit 63, the radio wave receiving unit 64, and the antenna unit 65 are mounted on a small mobile body 66. In this example, the small mobile body 66 is a drone.

[0048] 7 is a block diagram showing the configuration of the radio wave receiving unit according to the first embodiment of the present disclosure. First, the operation of the radio wave receiving unit 64 when the receiving device 6 receives control information from the control station 2 will be described.

[0049] The processing unit 640 included in the radio wave receiving unit 64 receives the control information transmitted from the control unit 63 and distributes it as necessary to the output control unit 641 and the frequency control unit 646. The output control unit 641 transmits information relating to measurement of the reception level, which is included in the control information, to the level measurement unit 645.

[0050] The frequency control unit 646 transmits information about the frequency included in the control information to the local oscillator 647. Based on the received information about the frequency, the local oscillator 647 generates radio waves of a specific frequency or frequency band and transmits them to the mixer 648.

[0051] Next, the operation of the radio wave receiving unit 64 when the receiving device 6 transmits the reception level of the radio waves received from the transmitting device 4 to the control station 2 will be described. The wideband filter 642 of the radio wave receiving unit 64 receives the radio waves from the antenna unit 65. The wideband filter 642 is a filter that can receive signals over a wide band. As a result of this operation, the frequency band that the receiving device 6 can receive becomes the band of the wideband filter 642.

[0052] The wideband filter 642 transmits the received radio waves to the amplifier 643. The amplifier 643 amplifies the received radio waves and transmits the amplified radio waves to the mixer 648. The mixer 648 transmits an output value based on the radio waves received from the local oscillator 647 and the amplifier 643 to the low-pass filter 649.

[0053] The low-pass filter 649 extracts radio waves corresponding to a specific bandwidth from the received output value and transmits the extracted radio waves to the wave detection unit 644. The wave detection unit 644 detects the extracted radio waves and transmits them to the level measurement unit 645.

[0054] The level measurement unit 645 measures the reception level of the detected radio waves and its change over time. Furthermore, the level measurement unit 645 transmits notification information including the measured reception level of the radio waves to the control unit 63. Note that the level measurement unit 645 may refer to information related to the measurement of the reception level to include information about the time when the reception level is maximum in the notification information.

[0055] As described above, the radio wave receiving unit 64 performs processing to measure the reception level at the frequency specified by the control station 2. In this case, the final reception bandwidth is the range of the bandwidth that the low-pass filter 649 can extract.

[0056] 8 is a graph illustrating an example of a measurement result of a reception level when the radio wave receiving unit according to the first embodiment of the present disclosure includes a low-pass filter. Here, an example is shown in which the reception level is measured at every specified time 90 for a frequency specified by the control station 2.

[0057] 8, the reception level is L1 at frequency f1, L2 at frequency f2, L3 at frequency f3, and L4 at frequency f4. That is, the reception level is greatest at L3. Therefore, the control station 2 determines f3, which is the frequency at which the reception level reaches L3, as the communication frequency.

[0058] 9 is a graph showing an example of a measurement result of a reception level when the radio wave receiving unit according to the first embodiment of the present disclosure does not have a low-pass filter. Here, an example is shown in which the reception level is measured for a specified time 90 when the control station 2 does not specify a frequency.

[0059] The reception level in the graph of Fig. 9 is Lα. Therefore, the control station 2 determines the frequency of the radio waves transmitted by the transmitting device 4 at the time when the reception level reaches Lα as the communication frequency. In this case, the control station 2 determines the communication frequency by referring to the known frequency of the radio waves transmitted by the transmitting device 4.

[0060] As described above, when the control station 2 does not specify a reception frequency, the final reception bandwidth is within the range of the bandwidth that can be extracted by the wideband filter 642. In this case, the frequency control unit 646, local oscillator 647, mixer 648, and low-pass filter 649 are not required, and the configuration of the radio wave receiving unit 64 can be simplified.

[0061] FIG. 10 is a flowchart illustrating processing performed by the wireless communication system according to the first embodiment of the present disclosure.

[0062] First, in step 100, the control station 2 transmits a control signal. Specifically, the control station 2 transmits a control signal including information about the radio waves to be transmitted by the transmitting device 4 to the transmitting device 4, thereby specifying the information about the radio waves to be transmitted by the transmitting device 4. Here, the information about the radio waves to be transmitted is information specifying the frequency and time of the radio waves. The control station 2 also transmits a control signal including information specifying the frequency and time of the radio waves to be received by the receiving device 6 to the receiving device 6.

[0063] In addition, instead of the control station 2 transmitting a control signal to the receiving device 6, the receiving device 6 may obtain the frequency and time of the radio waves received by acquiring the control signal transmitted from the control station 2 to the transmitting device 4.

[0064] Next, in step 102, the transmitting device 4 transmits radio waves. The radio waves transmitted by the transmitting device 4 at this time are determined in accordance with the control signal received from the control station 2. In this step, the transmitting device 4 transmits radio waves of a specified frequency for a specified time. Next, in step 104, the transmitting device 4 stops transmitting radio waves.

[0065] Next, in step 106, the receiver 6 detects the frequency and reception level of the received radio wave and notifies the control station 2. Next, in step 108, the control station 2 stores the notified frequency and reception level of the radio wave.

[0066] Next, in step 110, the measurer determines whether to continue the process. If yes, the process returns to step 100. If no, the process proceeds to step 112.

[0067] The measurement person may make the determination in step 110 based on, for example, whether a specific communication quality is satisfied. The case where the specific communication quality is satisfied may be, for example, when the VSWR becomes equal to or less than a specific threshold value, and the input and output impedances become equal.

[0068] In step 112, the control station 2 determines the communication frequency and ends the process. For example, the control station 2 determines the frequency at the timing when the reception level received by the receiving device 6 is at its maximum as the communication frequency. In other words, the control station 2 determines the frequency notified by the receiving device 6 as the frequency of the radio waves being transmitted by the transmitting device at the timing when the reception level is at its maximum as the communication frequency.

[0069] As described above, according to this embodiment, the reception level of wireless communication in the sky can be improved by optimizing the communication frequency using the receiving device 6 located in the sky.

[0070] 11 is a flowchart showing processing performed by a wireless communication system according to a second embodiment of the present disclosure. This embodiment differs from the first embodiment in that candidate communication frequencies are determined using ideal characteristics of an antenna acquired in advance in an ideal environment where the characteristics are not affected by the surrounding conditions, and estimation based on the actual characteristics.

[0071] First, in step 200, the control station 2 transmits a control signal. Specifically, the control station 2 transmits a control signal including information about the radio waves to be transmitted by the transmitting device 4 to the transmitting device 4, thereby specifying the information about the radio waves to be transmitted by the transmitting device 4. The control station 2 may also transmit a control signal including information about the measurement of the reception level to the receiving device 6.

[0072] Next, in step 202, the transmitting device 4 transmits radio waves. The radio waves transmitted by the transmitting device 4 at this time are determined in accordance with the control signal received from the control station 2. In this step, the transmitting device 4 transmits radio waves at a specified frequency and for a specified time. Next, in step 204, the transmitting device 4 stops transmitting radio waves.

[0073] Next, in step 206, the receiver 6 detects the reception level of the radio wave received and its change over time, and notifies the control station 2 of the result.

[0074] Next, in step 208, the control station 2 stores the notified radio wave reception levels. Specifically, the control station 2 receives a plurality of reception levels from the receiving device 6. Next, the control station 2 stores the received plurality of reception levels.

[0075] Next, in step 210, the measurer determines whether to continue the process. If yes, proceed to step 212. If no, proceed to step 214.

[0076] The measurement person may make the determination in step 210 based on, for example, whether a specific communication quality is satisfied. The case where the specific communication quality is satisfied may be, for example, when the VSWR becomes equal to or less than a specific threshold value, and the input and output impedances become equal.

[0077] In step 212, the control station 2 stores the candidate communication frequencies and returns to step 202. Specifically, the control station 2 first identifies the generation frequency for each of the stored multiple reception levels. Next, the control station 2 generates a correction characteristic by correcting the ideal characteristic so that it matches the multiple sets of reception levels and generated frequencies. Next, the control station 2 determines and stores the frequency at which the reception level is maximized in the correction characteristic as a candidate communication frequency.

[0078] The above correction is performed by, for example, curve fitting, which will be described later.

[0079] When returning to step 202, the radio wave transmitted by the transmitter 4 is the frequency stored as the candidate communication frequency in step 212.

[0080] In step 214, the control station 2 determines a communication frequency from the communication frequency candidates stored therein, and then ends the process. For example, the control station 2 determines, from the communication frequency candidates stored therein, the frequency at which the reception level is maximized as the communication frequency.

[0081] 12 is a graph illustrating a method for determining a communication frequency according to the second embodiment of the present disclosure. Here, an example is shown in which the control station 2 determines candidate communication frequencies by performing curve fitting based on the notified reception levels and the frequencies corresponding to each reception level.

[0082] First, the control station 2 performs curve fitting based on the current measurement point 91 a and the previous measurement point 91 b to obtain a correction characteristic 92 a. The curve fitting is performed using, for example, the sum of squares of residuals. Next, the control station 2 determines, based on the correction characteristic 92 a, a frequency 94 a that is estimated to have the highest reception level as a candidate communication frequency.

[0083] When multiple communication frequency candidates are obtained through the above process, the control station 2 performs curve fitting based on the current measurement point 91a, the previous measurement point 91b, and the measurement point 91c before that to obtain a correction characteristic 92b. The curve fitting is performed using, for example, the sum of squared residuals. Next, the control station 2 determines, based on the correction characteristic 92b, a frequency 94b that is estimated to have the highest reception level as a communication frequency candidate.

[0084] 13 is a graph showing ideal characteristics of an antenna according to the second embodiment of the present disclosure. The graph shows ideal characteristics held by the control station 2 as reception levels corresponding to the frequencies of radio waves received by the antenna unit 65. It is assumed that the antenna unit 65 exhibits a reception level L1 for frequency f1, a reception level L2 for frequency f2, a reception level L3 for frequency f3, a reception level L4 for frequency f4, and a reception level L5 for frequency f5.

[0085] 14 is a graph showing the actual characteristics of the antenna in the sky according to the second embodiment of the present disclosure. The graph shows the actual characteristics detected by the receiver 6 as the reception level of the radio waves received by the antenna unit 65 and the frequency corresponding to the reception level. Here, the antenna unit 65 detects a reception level Pα for frequency fα and a reception level Pβ for frequency fβ. Here, the difference between frequency fα and frequency fβ is defined as fΔ.

[0086] The candidate communication frequencies can be determined in step 212 by fitting the above-described actual characteristics to the above-described ideal characteristics. That is, based on the correction characteristics obtained by fitting, the frequency that is estimated to have the highest reception level is determined as the candidate communication frequency.

[0087] Curve fitting according to this embodiment will now be specifically described. Fig. 15 is a table showing ideal characteristics of an antenna according to the second embodiment of the present disclosure. Here, the table shows ideal characteristics held by the control station 2 as reception levels indicated according to the frequencies of radio waves received by the antenna unit 65.

[0088] In this table, frequencies f1 to fn are listed in ascending order. Below each frequency, the corresponding reception level L1 to Ln is listed. If the maximum reception level among L1 to Ln is reception level Ld, the corresponding frequency is fd.

[0089] 16 is a table illustrating actual characteristics in the sky of the antenna according to the second embodiment of the present disclosure. Here, the table illustrates actual characteristics detected by the receiving device 6 as reception levels of radio waves received by the antenna unit 65 and frequencies corresponding to the reception levels.

[0090] In this table, frequencies fγ, fα, fβ, and fe are listed in the order of measurement. Below each frequency, the corresponding reception levels Pγ, Pα, and Pβ are listed. Since frequency fe is a value to be used in the next measurement, the corresponding reception level is not listed.

[0091] 17 is a first flowchart illustrating a first curve fitting process according to the second embodiment of the present disclosure. Here, a case where a single candidate communication frequency can be determined will be mainly described. In the curve fitting process that follows, an example will be shown in which frequencies f1 to f5 are used based on the ideal characteristics of the antenna, and fγ, fα, and fβ are used based on the actual characteristics above the antenna. Also, assume that α<β.

[0092] First, variables are set in step 300. Here, the minimum frequency in fα and fβ is set to fa, the maximum frequency in fα and fβ is set to fb, the reception level at fa is set to Pa, and the reception level at fb is set to Pb. Next, in step 302, fΔ is set to fb-fa, and i=0.

[0093] Next, in step 304, i is set to i+1. Next, in step 306, fu, which is the frequency closest to fi+fΔ, is selected from f1 to f5. Next, in step 308, the residual sum of squares between fi and fa, and between fu and fb, is calculated. This residual sum of squares is defined as Ri.

[0094] Next, in step 310, it is determined whether fu is greater than fn. If it is greater, the process proceeds to step 312. If it is not greater, the process returns to step 304. The loop from steps 304 to 310 is called loop 1.

[0095] Next, in step 312, N=i and j=0 are set. Next, in step 314, fv, which is a frequency equal to or lower than f1+fΔ and closest to f1+fΔ, is selected from f1 to f5, and j=v is set.

[0096] Next, in step 316, fk, which is the frequency closest to fj-fΔ, is selected from f1 to f5. Next, in step 318, the residual sum of squares between fk and fa, and between fj and fb, is calculated. This residual sum of squares is defined as Rj.

[0097] Next, in step 320, it is determined whether fv is greater than fn. If it is, the process proceeds to step 324. If it is not greater, the process proceeds to step 322.

[0098] In step 322, i=i+1 and j=j+1 are set, and the process returns to step 316. The loop from step 316 to step 322 is called loop 2.

[0099] In step 324, the smallest Rs is selected from R1 to Ri. Next, in step 326, it is determined whether there is more than one Rs. If there is more than one, the process proceeds to step 334. If there is not more than one, the process proceeds to step 328.

[0100] In step 328, it is determined whether s is less than N. If it is, the process proceeds to step 332. If it is not less, the process proceeds to step 330.

[0101] In step 330, the process ends with fe=fb-fs+fd for the candidate communication frequency fe. In step 332, the process ends with fe=fa+fd-fs for the candidate communication frequency fe.

[0102] 18 is a second flowchart illustrating the first curve fitting process according to the second embodiment of the present disclosure. This flowchart is a continuation of the flowchart in FIG. 15 and mainly describes a case where a single candidate communication frequency cannot be determined.

[0103] First, variables are set in step 334. Here, the minimum frequency among fα, fβ, and fγ is set to fa, the second highest frequency among fα, fβ, and fγ is set to fb, and the maximum frequency among fα, fβ, and fγ is set to fg. Also, the reception level at fa is set to Pa, the reception level at fb is set to Pb, and the reception level at fg is set to Pg.

[0104] Next, in step 336, fΔ is set to fb-fa, fε is set to fg-fa, and i=0.

[0105] Next, in step 338, i is set to i+1. Next, in step 340, fu, which is the frequency closest to fi+fΔ, and fv, which is the frequency closest to fi+fε, are selected from f1 to f5. Next, in step 342, the residual sums of squares for fi and fa, fu and fb, and fv and fg are calculated.

[0106] Next, in step 344, it is determined whether fv is greater than fn. If it is greater, the process proceeds to step 346. If it is not greater, the process returns to step 338. The loop from steps 344 to 338 is called loop 3.

[0107] Next, variables are set in step 346. Here, fv, which is a frequency equal to or lower than f1+fΔ and closest to f1+fΔ, is selected from f1 to f5, and N=i and j=w.

[0108] Next, in step 348, fk, which is the frequency closest to fj-fΔ, and fx, which is the frequency closest to fj-fΔ+fε, are selected from f1 to f5. Next, in step 350, the residual sums of squares for fk and fa, fj and fb, and fx and fg are calculated.

[0109] Next, in step 352, it is determined whether fdi is greater than fn. If it is, the process proceeds to step 356. If it is not greater, the process proceeds to step 354.

[0110] In step 354, i=i+1 and j=j+1 are set, and the process returns to step 348. The loop from step 348 to step 354 is called loop 4.

[0111] 19 is a third flowchart illustrating the first curve fitting process according to the second embodiment of the present disclosure. This flowchart is a continuation of the flowchart in FIG. 16 and mainly describes a case where a single candidate communication frequency cannot be determined.

[0112] Variables are set in step 356. Here, fh, which is a frequency equal to or lower than fl+fε and closest to fl+fε, is selected from f1 to f5, and M=i and l=h.

[0113] Next, in step 358, fh, which is the frequency closest to fl-fε, and fm, which is the frequency closest to fl-fε+fΔ, are selected from f1 to f5. Next, in step 360, the residual sums of squares for fh and fa, fm and fb, and fl and fg are calculated.

[0114] Next, in step 362, it is determined whether fl is greater than fn. If it is, the process proceeds to step 366. If it is not greater, the process proceeds to step 364.

[0115] In step 364, i=i+1 and l=l+1 are set, and the process returns to step 360. The loop from step 360 to step 364 is called loop 5.

[0116] In step 366, Rs, which is the smallest among R1 to Ri, is selected. Next, in step 368, it is determined whether s is smaller than N. If it is smaller, the process proceeds to step 370. If it is not smaller, the process proceeds to step 372.

[0117] In step 370, the process ends by setting fe=fa+fd-fs for the candidate communication frequency fe.

[0118] In step 372, it is determined whether s is less than M. If it is, the process proceeds to step 374. If it is not less, the process proceeds to step 376.

[0119] In step 374, the candidate communication frequency fe is set to fe=fb+fd-fs, and the process is terminated. In step 376, the candidate communication frequency fe is set to fe=fg+fd-fs, and the process is terminated.

[0120] The method for determining a communication frequency according to the second embodiment will now be described in more detail. Fig. 20 is a diagram illustrating a specific example of loop 1 of the first curve fitting process according to the second embodiment of the present disclosure.

[0121] The four graphs, from left to right, show the residual sums of squares calculated in loop 1 when i = 1, i = 2, i = 3, and i = 4. To avoid repetition, only the example for i = 1 will be explained here.

[0122] First, in step 304, i=1 is set. Next, in step 306, f2, which is the frequency closest to f1+fΔ, is selected from f1 to f5. Next, in step 308, the residual sum of squares between f1 and fα and between f2 and fβ is calculated. This residual sum of squares is defined as R1.

[0123] Next, in step 310, it is determined whether f2 is greater than f5. Since it is not greater, the process returns to step 304.

[0124] In loop 1, the above-described process is repeated to obtain R1 to R4 as residual sums of squares.

[0125] FIG. 21 is a diagram illustrating a specific example of loop 2 in the first curve fitting process according to the second embodiment of the present disclosure.

[0126] The four graphs, from left to right, show the residual sums of squares calculated in loop 2 when j = 2, j = 3, j = 4, and j = 5. To avoid repetition, only the example for j = 2 will be explained here.

[0127] First, in step 316, f1, which is the frequency closest to f2-fΔ, is selected from f1 to f5. Next, in step 318, the residual sum of squares between f1 and fα and between f2 and fβ is calculated. This residual sum of squares is defined as R5.

[0128] Next, in step 320, it is determined whether f2 is greater than f5. Since it is not greater, the process proceeds to step 322. In step 322, i and j are incremented by 1, and the process returns to step 316.

[0129] In loop 2, the above process is repeated to obtain R5 to R8 as residual sums of squares.

[0130] 22 is a graph illustrating a first method for determining candidate communication frequencies in the first curve fitting process according to the second embodiment of the present disclosure. Fig. 22 is the same as the graph illustrating the residual sum of squares calculated in loop 1 when i = 4, which is the fourth graph from the left in Fig. 20.

[0131] As described above, R1 to R8 can be obtained as the residual sums of squares by the processing of loop 1 and loop 2. In the following step 324, Rs, which is the smallest among R1 to R8, is selected.

[0132] Here, assume that only R4 is minimum. In this case, fitting occurs when fα matches f4. Since the maximum value in the ideal characteristics is f3, the frequency at which the reception level is highest in the actual characteristics is estimated to be fα-(f4-f3). Therefore, fe, which is a candidate communication frequency, is determined to be fα-(f4-f3).

[0133] Fig. 23 is a graph showing a second method for determining candidate communication frequencies in the first curve fitting process according to the second embodiment of the present disclosure. Fig. 23 is similar to a graph plotting the measurement points from the previous time, the previous time, and the current time listed in the table shown in Fig. 16. fΔ is the difference between fα and fβ, and fε is the difference between fα and fγ.

[0134] If there are multiple Ri selected in step 324, the process proceeds to step 334, where new processing is started using the frequency fγ and reception level Pγ of the measurement point two times before. Then, by repeating the processing of loops 3 to 5, a new residual sum of squares is obtained. Then, in step 366, the smallest Rs among R1 to Ri is selected, and fe, which is a candidate communication frequency, is determined.

[0135] 24 is a graph illustrating a second curve fitting according to the second embodiment of the present disclosure. The curve fitting according to this embodiment may be performed using the interpolation of the reception level as shown in FIG. 24. In this case, R1 is expressed by Equation 1.

[0136]

[0137] 25 is a graph illustrating a third curve fitting according to the second embodiment of the present disclosure. The curve fitting according to this embodiment may be performed using the interpolation of the reception level as shown in FIG. 25. In this case, R1 is expressed by Equation 2.

[0138]

[0139] As described above, according to this embodiment, by optimizing the communication frequency using the receiving device 6 located in the sky, it is possible to improve the reception level and realize efficient communication in wireless communication in the sky. Furthermore, according to this embodiment, the communication frequency can be determined more quickly by using curve fitting.

[0140] 2 Control station 4 Transmitter 6 Receiver 92a Correction characteristics 92b Correction characteristics 94a Frequency 94b Frequency

Claims

1. A control station that is notified of the reception level of radio waves transmitted by a transmitting device from a receiving device that receives the radio waves in the sky, and that is configured to maintain ideal characteristics of the antenna of the receiving device and perform the following processes: specifying information about the radio waves transmitted by the transmitting device; receiving a plurality of reception levels from the receiving device; identifying a generation frequency for each of the plurality of reception levels; generating correction characteristics by correcting the ideal characteristics so that they are consistent with a plurality of sets of the reception levels and the generated frequencies; and determining the frequency at which the reception level is maximum in the correction characteristics as a communication frequency.

2. The control station according to claim 1, wherein the correction characteristics are obtained by curve fitting using a residual sum of squares.

3. The control station according to claim 1, wherein the correction characteristics are obtained by curve fitting using interpolation.

4. The control station according to any one of claims 1 to 3, wherein the plurality of reception levels are two reception levels.

Images