Low earth orbit satellite signal processing method and device and electronic equipment

Abstract

The invention provides a low-orbit satellite signal processing method and device and electronic equipment, and relates to the technical field of satellite navigation, and the method comprises the steps: carrying out the coarse capturing of a received signal, and obtaining the first carrier Doppler frequency offset of the received signal and the frame header position of a subframe of the received signal; performing frequency and phase compensation on the received signal based on the first carrier Doppler frequency offset to obtain a compensated signal; determining a part of signals starting from the frame header position in the compensated signals as target signals, and finely capturing the target signals to obtain second carrier Doppler frequency offset of the target signals and the frame header position of subframes of the target signals; and performing signal tracking and channel decoding based on the second carrier Doppler frequency offset and the frame header position of the subframe of the target signal to obtain message information in the received signal. The method can rapidly and accurately complete the capture of the received signals such as the SPT signals of the low-orbit satellite, and carries out the signal tracking and channel decoding, thereby rapidly and accurately obtaining the message information in the received signals.

Description

Technical Field

[0001] The present disclosure relates to the field of satellite navigation technology, and in particular to a method, device and electronic equipment for processing low-orbit satellite signals. Background Art

[0002] In low-orbit satellite communication scenarios, low-orbit satellites move at high speeds and use beam polling to broadcast burst signals such as SPT (Security Positioning and Timing) signals. In low-orbit satellite communication scenarios, it is very important to enable user terminals to quickly and accurately capture signals so that user terminals can quickly and accurately obtain the telegram information in the signals. Summary of the invention

[0003] The present disclosure aims to solve one of the technical problems in the related art at least to some extent.

[0004] To this end, the purpose of the present disclosure is to propose a low-orbit satellite signal processing method, device and electronic equipment, which can quickly and accurately complete the capture of received signals such as SPT signals of low-orbit satellites, and perform signal tracking and channel decoding, so as to quickly and accurately obtain the telegram information in the received signal.

[0005] The first aspect of the present disclosure provides a method for processing low-orbit satellite signals, including: coarsely capturing a received signal to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal; based on the first carrier Doppler frequency deviation, performing frequency and phase compensation on the received signal to obtain a compensated signal; determining a portion of the signal starting from the frame header position in the compensated signal as a target signal, and finely capturing the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal; based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal, performing signal tracking and channel decoding to obtain telegram information in the received signal.

[0006] The second aspect of the present disclosure provides a low-orbit satellite signal processing device, including: a coarse capture module, used to perform coarse capture on a received signal to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal; a compensation module, used to perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal; a fine capture module, used to determine a portion of the signal starting from the frame header position in the compensated signal as a target signal, and perform fine capture on the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal; a tracking and decoding module, used to perform signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal to obtain the telegram information in the received signal.

[0007] An embodiment of the third aspect of the present disclosure proposes an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are configured to execute the method for processing low-orbit satellite signals as described in the embodiment of the first aspect of the present disclosure.

[0008] The fourth aspect embodiment of the present disclosure provides a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable the computer to execute the low-orbit satellite signal processing method as described in the first aspect embodiment of the present disclosure.

[0009] The fifth aspect embodiment of the present disclosure proposes a computer program product. When the instructions in the computer program product are executed by a processor, the method for processing low-orbit satellite signals as described in the first aspect embodiment of the present disclosure is implemented.

[0010] The present invention discloses a method, device, electronic device, computer-readable storage medium and computer program product for processing low-orbit satellite signals, which obtains a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal by coarsely capturing the received signal, performs frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal, determines a portion of the signal starting from the frame header position in the compensated signal as a target signal, and performs fine capture on the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal, performs signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal, and obtains telegram information in the received signal. The method and device disclosed in the present invention can quickly and accurately complete the capture of received signals such as SPT signals of low-orbit satellites, and perform signal tracking and channel decoding, thereby quickly and accurately obtaining the telegram information in the received signal.

[0011] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description or learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and / or additional aspects and advantages of the present disclosure will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0013] Figure 1 A schematic diagram of the architecture of a communication system provided by an embodiment of the present disclosure;

[0014] Figure 2 is a flowchart of a method for processing low-orbit satellite signals provided by an embodiment of the present disclosure;

[0015] Figure 3 A schematic diagram of a signal frame structure provided by an embodiment of the present disclosure;

[0016] Figure 4 A schematic flow chart of another method for processing low-orbit satellite signals provided by an embodiment of the present disclosure;

[0017] Figure 5 A schematic diagram of a method for acquiring a detection signal provided in an embodiment of the present disclosure;

[0018] Figure 6 A schematic flow chart of another method for processing low-orbit satellite signals provided by an embodiment of the present disclosure;

[0019] Figure 7 A schematic flow chart of another method for processing low-orbit satellite signals provided by an embodiment of the present disclosure;

[0020] Figure 8 A schematic diagram of a signal frame structure and precise capture provided by an embodiment of the present disclosure;

[0021] Fig. 9 A schematic diagram of a fine capture method provided by an embodiment of the present disclosure;

[0022] Fig.10 A schematic diagram of the structure of a low-orbit satellite signal processing device provided by an embodiment of the present disclosure;

[0023] Fig.11 It is a block diagram of an electronic device for signal processing according to an exemplary embodiment. DETAILED DESCRIPTION

[0024] Embodiments of the present disclosure are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be construed as limiting the present disclosure.

[0025] In order to better understand the low-orbit satellite signal processing method, device and electronic device disclosed in the embodiments of the present disclosure, the communication system to which the low-orbit satellite signal processing method disclosed in the embodiments of the present disclosure is applicable is first described below.

[0026] See also Figure 1 , Figure 1 The following is a schematic diagram of the architecture of a communication system provided by an embodiment of the present disclosure. Figure 1 The satellite communication system is used as an example for illustration. The satellite communication system may include but is not limited to a low-orbit satellite 101 and a user terminal 102. Figure 1 The number and form of the devices shown are for illustrative purposes only and do not constitute a limitation on the embodiments of the present disclosure. In actual applications, two or more low-orbit satellites and two or more user terminals may be included.

[0027] The low-orbit satellite 101 in the embodiment of the present disclosure is an entity for transmitting or receiving signals. The embodiment of the present disclosure does not limit the specific technology and specific equipment form used by the low-orbit satellite.

[0028] The user terminal 102 in the embodiment of the present disclosure refers to a processing device for communicating with a low-orbit satellite within the coverage beam range of the low-orbit satellite. For example, the user terminal can be a car with satellite communication function, a smart car, a mobile phone, a wearable device, a tablet computer, etc. The embodiment of the present disclosure does not limit the specific technology and specific device form adopted by the user terminal.

[0029] It can be understood that the satellite communication system described in the embodiment of the present disclosure is for the purpose of more clearly illustrating the technical solution of the embodiment of the present disclosure, and does not constitute a limitation on the technical solution provided by the embodiment of the present disclosure. A person skilled in the art can know that with the evolution of the system architecture and the emergence of new business scenarios, the technical solution provided by the embodiment of the present disclosure is also applicable to similar technical problems.

[0030] Taking the above-mentioned satellite communication system as an example, in the relevant technology, the processing method of the satellite navigation signal is roughly as follows: the Global Navigation Satellite System (GNSS) signal passes through the antenna of the receiver in the user terminal and reaches the RF front end. After mixing and filtering with the local oscillator frequency of the receiver and analog-to-digital conversion (ADC conversion), the intermediate frequency digital signal is output. The intermediate frequency digital signal is downsampled and filtered to output the baseband signal. The baseband signal is captured through linear three-dimensional search, and then the signal enters the tracking loop, completes carrier stripping and pseudo-code stripping, outputs the carrier observation value, and is demodulated, decoded, and analyzed to output the navigation message. In the above method, the satellite navigation signal has low landing power and is easily interfered with. It has the characteristics of low landing power and weak anti-interference ability.

[0031] Low-orbit satellite safe positioning and timing is a technology that uses the Doppler frequency observation of low-orbit satellite communication and navigation fusion signals for positioning and timing. Unlike the continuous carrier and ranging code reception of GNSS navigation continuous broadcast signals in related technologies, the SPT signal based on low-orbit communication satellites is a burst signal. The satellite broadcasts the SPT signal in a beam rotation manner. The rotation period is much longer than the signal frame length. When the satellite does not broadcast the signal, the receiver cannot capture the signal. For this broadcast method, if the search and capture method in related technologies is used, the average capture time will be greatly increased and the capture accuracy will be reduced.

[0032] Among them, the signal capture in the related technology is to perform correlation operation between the receiver's replica signal and the received signal. If a large correlation peak is generated, it means that the replica signal is not much different from the received signal and can enter the pull-in range of the tracking loop. The carrier frequency and code phase of the copied signal in the capture process are set by the search strategy. The good autocorrelation characteristics of the code phase are used to estimate the approximate values ​​of the code phase and carrier frequency of the received signal, so that the errors of these two parameters are less than the pull-in range of the carrier loop and the code loop, and the capture of the navigation signal is completed. According to different signal search strategies, the capture method can be divided into linear search, parallel frequency search and parallel code phase search.

[0033] Among them, the linear search strategy is to divide the search into small search units in three dimensions of frequency, time and pseudocode, and complete the full-domain search according to the set search direction and step size. This method is time-consuming; the parallel frequency search and parallel code phase search strategies use the correlated signal for Fourier transform and compare the amplitude in the frequency domain to determine whether the capture is successful. It has a faster search speed than the linear search, but the estimation accuracy is poorer.

[0034] Different from the traditional GNSS satellite navigation signal, the SPT signal is a burst signal, which uses a multi-beam round-robin signal broadcasting method and the high dynamic characteristics of low-orbit satellites, which brings new challenges to signal capture. The GNSS signal capture method in the related technology does not meet the SPT signal capture performance requirements of the high dynamic characteristics of low-orbit satellites.

[0035] The embodiments of the present disclosure provide a method, device and electronic device for processing low-orbit satellite signals, which perform coarse capture of received signals to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal, perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal, determine a portion of the signal starting from the frame header position in the compensated signal as a target signal, and perform fine capture of the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal, perform signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal, and obtain telegram information in the received signal. The method can quickly and accurately complete the capture of received signals such as SPT signals of low-orbit satellites, perform signal tracking and channel decoding, and thus quickly and accurately obtain the telegram information in the received signal.

[0036] The following is a detailed introduction to the low-orbit satellite signal processing method, device and electronic equipment provided by the present invention in conjunction with the accompanying drawings.

[0037] Figure 2 It is a flowchart of a method for processing low-orbit satellite signals provided in an embodiment of the present disclosure.

[0038] It should be noted that the method is applied to any device capable of implementing the method, such as a user terminal, and is executed by a low-orbit satellite signal processing device. The low-orbit satellite signal processing device may be a device such as a user terminal, or may be configured in a device such as a user terminal, such as a receiver in a user terminal, and the present disclosure does not limit this.

[0039] like Figure 2 As shown, the method may include but is not limited to the following steps 201-204.

[0040] Step 201 , coarsely capture a received signal to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal.

[0041] The received signal may be a burst signal such as an SPT signal of a low-orbit satellite, or other types of signals, which are not limited in the present disclosure. The received signal carries carrier Doppler frequency deviation and message information.

[0042] The first carrier Doppler frequency deviation is an approximate value of the estimated carrier Doppler frequency deviation of the received signal.

[0043] The frame header position of the subframe of the received signal is an estimated rough position of the frame header of the subframe of the received signal.

[0044] In some embodiments, reference Figure 3 The frame structure of the received signal can be composed of a continuous wave (CW) signal, a unique word (UW) code, a pilot pseudo random noise (PRN) code and a data PRN code ( Figure 3 The frame header position of the subframe of the received signal can be represented by the starting position of the unique word UW code piece in the subframe in the received signal. The starting position of the unique word UW code piece in the subframe in the received signal is the position marked by the starting edge of the UW code piece in the subframe of the received signal. The continuous wave signal is a continuous periodic signal.

[0045] In some embodiments, the received signal may be coarsely captured to quickly estimate an approximate value of a carrier Doppler frequency offset of the received signal and a rough position of a frame head of a subframe of the received signal.

[0046] In some embodiments, taking the received signal as a burst signal as an example, the burst signal that passes through the antenna of the receiver and reaches the RF front end can be mixed and filtered with the local oscillator frequency of the receiver to obtain a mixed signal, and the mixed signal is converted into an analog-to-digital signal to obtain an intermediate frequency digital signal, and the intermediate frequency digital signal is used as the received signal in step 201.

[0047] In some embodiments, taking the received signal as a burst signal as an example, the burst signal that reaches the RF front end through the antenna of the receiver can be mixed and filtered with the local oscillator frequency of the receiver to obtain a mixed signal, the mixed signal is analog-to-digital converted to obtain an intermediate frequency digital signal, and the intermediate frequency digital signal is downsampled, and the downsampled signal is used as the received signal in step 201. By downsampling the intermediate frequency digital signal, the amount of calculation for subsequent frequency offset estimation can be reduced.

[0048] Correspondingly, before step 201, it can also include: mixing and filtering the burst signal that reaches the RF front end through the antenna of the receiver with the local oscillator frequency of the receiver to obtain a mixed signal; performing analog-to-digital conversion on the mixed signal to obtain an intermediate frequency digital signal; and downsampling the intermediate frequency digital signal to obtain a received signal.

[0049] The receiver is a receiver in a user terminal.

[0050] The intermediate frequency digital signal can be in the form shown in the following formula (1):

[0051]

[0052] Among them, S IF Represents the intermediate frequency digital signal; P S represents the signal power of the burst signal; C(t) represents the pseudo code; D(t) represents the message bit, i.e., the message information in the present disclosure; τ represents the time delay caused in the transmission process; ω IF Represents the intermediate frequency digital signal S IF ; φ(t) represents the initial carrier phase of C(t); n(t) represents white noise, whose power spectrum can be considered as a constant.

[0053] In some embodiments, downsampling the intermediate frequency digital signal to obtain a received signal may include: sequentially inputting the intermediate frequency digital signal into a cascade-integrator-comb (CIC) decimation filter, a CIC compensation filter, and a half-band decimation filter to sequentially perform decimation filtering, compensation filtering, and decimation filtering on the intermediate frequency digital signal to obtain a received signal.

[0054] Assuming that the tap coefficient of the CIC decimation filter is D1, the tap coefficient of the CIC compensation filter is D2, and the tap coefficient of the half-band decimation filter is D3, the sampling frequency of the received signal Fp = F S / (D1*D2*D3). Among them, F S Indicates the sampling frequency of the intermediate frequency digital signal.

[0055] For example, assuming that an intermediate frequency digital signal is used as the received signal, taking 8-bit data as an example, after 1 / 2 encoding and 32-fold spread spectrum, the data broadcasting of a time length of T_bit=8ms (where T_bit represents the time length of data broadcasting) is completed, and the code rate after spread spectrum Rc=64KHz (kilohertz), and the sampling frequency F of the intermediate frequency digital signal is obtained by interpolation filtering. S The signal frequency is 38.4MHz (megahertz), the channel coding of the signal adopts convolutional code, and the modulation method adopts phase shift keying MPSK modulation (taking QPSK as an example). After propagation between the satellite and the ground, the signal randomly modulates the carrier Doppler frequency of ±40kHz and the Doppler frequency change rate of 200Hz / s (hertz per second) to meet the scenario simulation of the high dynamic characteristics of low-orbit satellites.

[0056] Assume that the intermediate frequency digital signal is sequentially input into the CIC decimation filter, CIC compensation filter, and half-band decimation filter for downsampling to reduce the amount of calculation for subsequent frequency offset estimation. Among them, the tap coefficient D1 of the CIC decimation filter is 15, the cascade filter is 4 levels, the tap coefficient D2 of the CIC compensation filter is 2, the stopband attenuation is 80dB (decibel), and the tap coefficient D3 of the half-band decimation filter is 2. Then the sampling frequency Fp of the received signal obtained after downsampling is Fp = FS / (D1*D2*D3)=640kHz.

[0057] Step 202: Perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal.

[0058] In some embodiments, the received signal may be frequency and phase compensated based on the first carrier Doppler frequency offset by down-converting the received signal to a zero intermediate frequency to obtain a compensated signal in the manner shown in the following formula (2):

[0059] Data_out=Data_in.*exp(-1i*2*π*fd*n / Fp) (2)

[0060] Wherein, Data_in represents the complex sampling point sequence of the received signal; Data_out represents the compensated signal; fd represents the first carrier Doppler frequency deviation; n represents the nth sampling point of the received signal; and Fp represents the sampling frequency of the received signal.

[0061] Step 203, determine the portion of the signal starting from the frame header position in the compensated signal as the target signal, and perform precise capture on the target signal to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal.

[0062] The second carrier Doppler frequency deviation is the approximate value of the estimated carrier Doppler frequency deviation of the target signal, that is, the approximate value of the carrier Doppler frequency deviation of the compensated signal. Since the compensated signal is a signal obtained by frequency and phase compensation of the received signal based on the first carrier Doppler frequency deviation, the target signal starting from the frame header position of the subframe in the compensated signal is precisely captured, and the approximate value of the second carrier Doppler frequency deviation obtained is the residual Doppler frequency deviation after coarse capture of the received signal. Compared with the approximate value of the first carrier Doppler frequency deviation, the value of the residual Doppler frequency deviation is very small. For example, assuming that the first carrier Doppler frequency deviation is several thousand hertz, the second carrier Doppler may be only a few hertz.

[0063] The frame header position of the subframe of the target signal is the estimated frame header position of the subframe of the target signal, which can be represented by the starting position of the unique word UW code chip in the subframe in the target signal. The starting position of the unique word UW code chip in the subframe in the target signal is the starting edge mark position of the UW code chip in the subframe of the target signal.

[0064] It can be understood that, in the embodiment of the present disclosure, by first performing a coarse capture on the received signal, the approximate value of the carrier Doppler frequency deviation of the received signal can be quickly estimated. By performing frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal, and performing fine capture on the target signal starting from the frame header position in the compensated signal, the residual Doppler frequency deviation after the coarse capture can be accurately determined, so that the carrier Doppler frequency deviation of the received signal can be accurately determined by combining the coarse capture and fine capture. Moreover, since the target signal is a partial signal starting from the frame header position in the compensated signal, the target signal is finely captured to determine the frame header position of the subframe of the target signal, which is equivalent to further determining the frame header position of the subframe of the received signal on the basis of determining the frame header position of the subframe of the received signal by coarse capture, and the obtained frame header position of the subframe is more accurate. Thus, the capture of received signals such as SPT signals of low-orbit satellites can be completed quickly and accurately.

[0065] Step 204: Based on the Doppler frequency deviation of the second carrier and the frame header position of the subframe of the target signal, signal tracking and channel decoding are performed to obtain the message information in the received signal.

[0066] In some embodiments, the target signal can be frequency and phase compensated based on the second carrier Doppler frequency deviation, and then the partial signal starting from the frame header position of the subframe in the compensated target signal is used as the input of the phase-locked tracking loop, and input into the phase-locked tracking loop for signal tracking to obtain more accurate carrier Doppler frequency deviation and pseudo-code stripped data information, and then through channel decoding, the telegram information of the received signal is obtained.

[0067] The phase-locked tracking loop may be, for example, a binary phase shift keying (BPSK) COSTAS loop in the related art, or other types of phase-locked tracking loops, which are not limited in the present disclosure.

[0068] The implementation process of step 204 may refer to related technologies and will not be described in detail here.

[0069] In summary, the method for processing low-orbit satellite signals provided by the embodiments of the present invention performs coarse capture of the received signal to obtain the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal, performs frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain the compensated signal, determines the part of the signal starting from the frame header position in the compensated signal as the target signal, and performs fine capture of the target signal to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal, performs signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal, and obtains the telegram information in the received signal. The method can quickly and accurately complete the capture of received signals such as SPT signals of low-orbit satellites, and perform signal tracking and channel decoding, so as to quickly and accurately obtain the telegram information in the received signal.

[0070] In order to clearly explain how the above embodiment performs coarse capture on the received signal to obtain the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal, the following is a description of how the above embodiment performs coarse capture on the received signal to obtain the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal. Figure 4 , the processing method of low-orbit satellite signals provided in the embodiment of the present disclosure is further explained.

[0071] Figure 4 A flowchart of another method for processing low-orbit satellite signals provided in an embodiment of the present disclosure.

[0072] like Figure 4 As shown, the method for processing low-orbit satellite signals may include the following steps 401-406.

[0073] Step 401, detecting whether a continuous wave signal exists in a received signal, wherein the frame structure of the received signal includes a continuous wave signal and a unique codeword.

[0074] In some embodiments, reference Figure 3 The frame structure of the received signal may include: a continuous wave CW signal, a unique word UW code chip, a pilot PRN code and a data PRN code ( Figure 3 The frame header position of the subframe of the received signal can be represented by the starting position of the unique word UW chip in the subframe in the received signal. Whether the coarse capture is successful can be determined by detecting whether there is a continuous wave CW signal in the received signal. The continuous wave signal is a continuous periodic signal with a large amplitude in the frequency domain, which is helpful for the rapid detection of burst signals.

[0075] In some embodiments, step 401 may be implemented by following the steps 401a-401d.

[0076] Step 401a, according to a preset detection step length, the detection time window is moved along a set direction on the received signal to select multiple detection signals.

[0077] The detection step size can be set as needed.

[0078] The length of the detection time window can be set as needed.

[0079] The preset direction may be a time domain direction.

[0080] The number of detection signals can be set as needed, such as 2, 3, etc., and the present disclosure does not impose any limitation on this.

[0081] refer to Figure 5 , the received signal may include CW signal and other signals ( Figure 5 Other), the detection time window can be moved along the time domain direction on the received signal according to the preset detection step length, and the signal in the detection time window is used as the detection signal. Thus, multiple detection signals can be selected by moving the detection time window multiple times. Among them, Figure 5 The first and second arrows from the left in the lower middle section represent the start time of the detection time window. Figure 5 The third arrow and the fourth arrow from the left in the lower middle section respectively indicate the end time of the detection time window.

[0082] In some embodiments, the detection step length and the time length of the detection time window may satisfy the following formula (3):

[0083] (T_step / 2)+ T_detect<=T_CW (3)

[0084] Wherein, T_step represents the detection step length, T_detect represents the time length of the detection time window, and T_CW represents the frame length of the continuous wave signal.

[0085] Step 401b, obtaining the signal-to-noise ratio of each of the multiple detection signals, and performing Fourier transform on each of the multiple detection signals to obtain the frequency spectrum and power spectrum of the corresponding signal.

[0086] Step 401c: based on the signal-to-noise ratios of the multiple detection signals, and the frequency spectra and power spectra of the multiple detection signals, detect whether the multiple detection signals meet the coarse capture condition.

[0087] In some embodiments, coarse capture conditions may include: the peak value of the frequency spectrum of each detection signal is higher than a first threshold and the main-sidelobe ratio of the power spectrum is higher than a second threshold, the first difference between adjacent detection signals in multiple detection signals is lower than a third threshold, and the second difference between adjacent detection signals in multiple detection signals is lower than the frequency resolution of the received signal.

[0088] Among them, the main-sidelobe ratio of the power spectrum is the ratio of the main lobe maximum value to the sidelobe maximum value of the power spectrum; the first difference is the difference in signal-to-noise ratios of adjacent detection signals; and the second difference is the difference between the frequencies corresponding to the peak values ​​of the frequency spectra of adjacent detection signals.

[0089] The first threshold and the third threshold can be set as needed. For example, the third threshold can be 3dB.

[0090] The sidelobe maximum value can be selected from the frequency points outside the main peak ±N1bins of the spectrum, where bins = Nfft_Points / N2, where N1 and N2 are preset coefficients that can be set based on experience. Nfft_Points represents the number of data points of the Fourier transform.

[0091] The second threshold can be set according to a set false alarm probability, wherein the false alarm probability can be set as required.

[0092] For example, the relationship between the second threshold and the false alarm probability can be shown as formula (4):

[0093]

[0094] Where Vt represents the second threshold, σ n Represents the power variance of the preset noise signal, P fa represents the false alarm probability.

[0095] The frequency resolution of the received signal can be obtained by the following formula (5):

[0096] Δf=Fp / Nfft_Points(5)

[0097] Wherein, Δf represents the frequency resolution of the received signal, Fp represents the sampling frequency of the received signal, and Nfft_Points represents the number of data points of the Fourier transform.

[0098] Wherein, Nfft_Points can be obtained by Nfft_Points=2exp(log2(N_Points)+1). Wherein, N_Points=T_detect*Fp. N_Points represents the number of sampling points of the received signal.

[0099] Step 401d, when the multiple detection signals meet the coarse capture condition, determine that there is a continuous wave signal in the received signal; and when the multiple detection signals do not meet the coarse capture condition, determine that there is no continuous wave signal in the received signal.

[0100] Through steps 401a-401d, it is possible to quickly search for continuous wave signals in received signals by Fourier transform in a sliding detection manner.

[0101] Step 402: when the existence of the continuous wave signal is detected, determine that the coarse capture is successful, and determine the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation.

[0102] In some embodiments, when detecting whether there is a continuous wave signal in the received signal by the method shown in steps 401a-401d, due to the randomness of the subframe starting point of the burst signal, when the signal is strong, if multiple consecutive detection signals meet the coarse capture condition, the detection result can be obtained based on the first detection signal. That is, step 402 can be implemented in the following manner: based on the starting position of the first detection signal in the received signal among the multiple detection signals, determine the starting position of the continuous wave signal in the received signal; based on the power spectrum of the first detection signal, determine the first carrier Doppler frequency deviation.

[0103] In some embodiments, the starting position of the first detection signal among the multiple detection signals in the received signal can be determined as the starting position of the continuous wave signal in the received signal. For example, assuming that according to the detection step length, the detection time window is moved along the time domain direction on the received signal, and three detection signals are selected, that is, Figure 5 On the received signal shown, the detection time window is moved from left to right, and three detection signals are selected. The three detection signals meet the coarse capture conditions. Then, the starting position of the first selected detection signal in the received signal, that is, when the detection signal is selected for the first time, the starting time of the detection time window corresponding to the position on the received signal, can be determined as the starting position of the continuous wave signal in the received signal.

[0104] It should be noted that in the embodiments of the present disclosure, the detection signal is detected to detect whether there is a continuous wave signal in the received signal. When the presence of the continuous wave signal is detected, the starting position of the continuous wave signal in the received signal is determined based on the starting position of the first detection signal among multiple detection signals in the received signal. Since the detection time window is moved according to the detection step to select the detection signal, the setting of the detection step can affect the accuracy of the determined starting position of the continuous wave signal in the received signal. The smaller the detection step, the higher the accuracy of the determined starting position of the continuous wave signal in the received signal.

[0105] In some embodiments, determining the first carrier Doppler frequency deviation based on the power spectrum of the first detection signal may include: obtaining the frequency corresponding to the maximum power spectrum amplitude of the first detection signal based on the power spectrum of the first detection signal; and determining the first carrier Doppler frequency deviation based on the frequency corresponding to the maximum power spectrum amplitude and the frequency resolution of the received signal.

[0106] The frequency resolution of the received signal may be multiplied by the frequency corresponding to the maximum power spectrum amplitude to obtain the first carrier Doppler frequency deviation.

[0107] In this way, the approximate value of the carrier Doppler frequency offset of the received signal and the rough position of the frame head of the subframe of the received signal can be quickly estimated.

[0108] Step 403: Based on the starting position of the continuous wave signal in the received signal, determine the starting position of the unique word code chip in the subframe in the received signal to determine the frame header position of the subframe of the received signal.

[0109] In some embodiments, reference Figure 3 The frame structure of the received signal shown in the figure can determine the starting position of the unique word code piece in the received signal based on the starting position of the continuous wave signal in the received signal and the frame length of the continuous wave signal after determining the starting position of the continuous wave signal in the received signal.

[0110] Step 404: Perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal.

[0111] The implementation process and principle of step 404 may refer to the description of other embodiments and will not be described in detail here.

[0112] The following takes the number of detection signals as 3 as an example. Figure 6 , the exemplary implementation process of the above steps 401-404 is illustrated.

[0113] refer to Figure 6 , the received signal Data_in can be cached, and the first detection signal can be selected on the received signal through the detection time window, and the first detection signal can be Fourier transformed (FFT) to obtain the frequency deviation and power spectrum of the first detection signal. Further, it can be determined whether the peak value of the spectrum of the first detection signal is higher than the first threshold. When the peak value of the spectrum of the first detection signal is higher than the first threshold, it can be further determined whether the main-sidelobe ratio of the power spectrum of the first detection signal is higher than the second threshold. When the peak value of the spectrum of the first detection signal is higher than the first threshold and the main-sidelobe ratio of the power spectrum is higher than the second threshold, the consistency judgment is passed, and the continuous detection count Cnt (wherein the initial value of Cnt is 0) can be added by 1, and the value of the continuous detection count Cnt is 1 at this time. Among them, since when the signal is strong, the main peak of the spectrum of the spread spectrum signal will also exceed the first threshold, so in order to ensure the accuracy of the detection result, it is necessary to make further judgments based on the power spectrum of the first detection signal when the peak value of the spectrum of the first detection signal is higher than the first threshold.

[0114] Furthermore, the detection time window can be moved along the time domain direction on the received signal according to the detection step length to select a second detection signal on the received signal, and the second detection signal is subjected to Fourier transform (FFT) to obtain the frequency deviation and power spectrum of the second detection signal. Further, it can be determined whether the peak value of the spectrum of the second detection signal is higher than the first threshold. In the case where the peak value of the spectrum of the second detection signal is higher than the first threshold, it can be further determined whether the main-sidelobe ratio of the power spectrum of the second detection signal is higher than the second threshold. In the case where the peak value of the spectrum of the second detection signal is higher than the first threshold and the main-sidelobe ratio of the power spectrum is higher than the second threshold, the consistency judgment is passed, and the continuous detection count Cnt can be increased by 1. At this time, the value of the continuous detection count Cnt is 2.

[0115] Furthermore, the detection time window can be moved along the time domain direction on the received signal according to the detection step to select a third detection signal on the received signal, and the third detection signal can be detected in a similar manner as described above. If the consistency judgment is passed, the continuous detection count Cnt can be increased by 1. At this time, the value of the continuous detection count Cnt is 3.

[0116] When the value of the continuous detection count Cnt is 3, and the first difference of adjacent detection signals in the three detection signals is lower than the third threshold, and the second difference is lower than the frequency resolution of the received signal, it can be determined that the three detection signals meet the coarse capture condition, and there is a continuous wave signal in the received signal, and the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation are determined, and based on the starting position of the continuous wave signal in the received signal, the starting position of the unique word code piece in the subframe in the received signal is determined to determine the frame header position of the subframe of the received signal. Then, the frame header position of the subframe of the received signal and the first carrier Doppler frequency deviation can be output, and based on the first carrier Doppler frequency deviation, the received signal is compensated for frequency and phase to obtain the compensated signal Data_out.

[0117] Step 405: determine the portion of the signal starting from the frame header position in the compensated signal as the target signal, and perform precise capture on the target signal to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal.

[0118] Step 406: Based on the Doppler frequency deviation of the second carrier and the frame header position of the subframe of the target signal, signal tracking and channel decoding are performed to obtain the message information in the received signal.

[0119] The implementation process and principle of steps 405-406 may refer to the description of other embodiments and will not be described in detail here.

[0120] In summary, the method for processing low-orbit satellite signals provided by the embodiments of the present disclosure detects whether there is a continuous wave signal in the received signal, wherein the frame structure of the received signal includes a continuous wave signal and a unique word code piece, and when the continuous wave signal is detected, determines that the coarse capture is successful, and determines the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation, and determines the starting position of the unique word code piece in the subframe in the received signal based on the starting position of the continuous wave signal in the received signal to determine the frame header position of the subframe of the received signal, and performs frequency and Phase compensation is performed to obtain a compensated signal, and part of the signal starting from the frame header position in the compensated signal is determined as the target signal. The target signal is precisely captured to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal. Based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal, signal tracking and channel decoding are performed to obtain the telegram information in the received signal. The signal tracking and channel decoding can be performed to quickly and accurately capture the received signals such as the SPT signal of the low-orbit satellite, and the telegram information in the received signal can be quickly and accurately acquired.

[0121] In order to clearly explain how the above embodiment accurately captures the target signal and obtains the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal, the following is combined with Figure 7 , the processing method of low-orbit satellite signals provided in the embodiment of the present disclosure is further explained.

[0122] Figure 7 A flowchart of another method for processing low-orbit satellite signals provided in an embodiment of the present disclosure.

[0123] like Figure 7 As shown, the process of accurately capturing the target signal may include the following steps 701-705.

[0124] Step 701: Filter the target signal to obtain a baseband signal.

[0125] In some embodiments, the target signal may be input into a CICI filter for data low-pass filtering, and the signal after the low-pass filtering may be further input into a matched filter to obtain a baseband signal.

[0126] The single-side bandwidth of the baseband signal is (1+α)*Rc / 2. α represents the roll-off coefficient of the matching filter, which is consistent with the shaping filter at the signal transmitting end, for example, 0.35. Rc represents the symbol rate, that is, the data rate.

[0127] In addition, in order to reduce the amount of subsequent calculations, the CIC filter extraction coefficient D4 can be set, for example, D4 ​​= 5, so that when the data rate is 640kHz, the data rate Rc can be reduced from 640kHz to 128kHz. Further, the symbols can be sampled, for example, the number of sampling points per symbol sps = 4, then the symbol rate can be reduced to Rc = 32kHz.

[0128] Step 702: Generate a carrier signal having a carrier frequency based on a pre-stored carrier frequency of a received signal.

[0129] Step 703: Generate a target code including a unique word code chip and a pilot pseudo-random noise code based on the pre-stored unique word code chip and the pilot pseudo-random noise code.

[0130] Step 704, the carrier signal and the target code are correlated with the baseband signal to obtain a correlation processing result.

[0131] In some embodiments, reference Figure 8 , determine the frame header position of the subframe in the received signal through coarse capture, and perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal, determine the part of the signal starting from the frame header position of the subframe in the compensated signal as the target signal, filter the target signal, and after obtaining the baseband signal, the unique word UW code chip + pilot PRN code can be used as the synchronization header, extract the data length N_Pionts=(T_UW+T_PRN)*Rc symbol sampling points from the baseband signal, and perform correlation processing with the synchronization header to obtain the correlation processing result. Among them, T_UW represents the time length of the UW code chip, and T_PRN represents the time length of the pilot RPN code.

[0132] Among them, the frame header position of the subframe of the received signal, that is, Figure 8 The position marked by UW_toa in the figure can be determined by the starting position of the continuous wave CW signal in the received signal, that is, Figure 8 The position marked by CW_toa is determined by the frame length of the CW signal.

[0133] Step 705: Perform Fourier transform on the correlation processing result, and determine the second carrier Doppler frequency offset and the frame header position of the subframe of the target signal based on the Fourier transform result.

[0134] The frame header position of the subframe of the target signal can be represented by the starting position of the unique word UW code piece in the subframe in the target signal.

[0135] In some embodiments, the process of steps 702-705 can be performed by Fig. 9 The method shown is implemented.

[0136] Specifically, a carrier signal with a carrier frequency can be generated based on the carrier frequency of the pre-stored received signal through a carrier NCO (Numerically Controlled Oscillator). The carrier signal includes two mutually orthogonal carrier signals, namely, an I-way (In-Phase, in-phase) carrier signal and a Q-way (Quadrature, phase shifted 90 degrees) carrier signal, and the phase difference between the two carrier signals is 90 degrees. And through the UW+PRN generator, a target code including a unique word UW code chip and a pilot PRN code is generated.

[0137] By correlating the carrier signal and the target code with the baseband signal, the correlation processing result can be obtained, and then the correlation processing result is Fourier transformed to obtain the Fourier transform result. The Fourier transform result is modulo, and the maximum value exceeding the set threshold and its corresponding frequency index are found. The position corresponding to the maximum value can be used as the frame header position of the subframe in the target signal, and the residual second carrier Doppler frequency deviation is calculated based on the frequency index. At this time, the precise capture is successful.

[0138] The method for precisely capturing a target signal in an embodiment of the present disclosure is a parallel frequency search method. Through this method, the residual carrier Doppler frequency deviation of the received signal after compensation by the first carrier Doppler frequency deviation can be accurately determined, and the frame header position of the subframe in the target signal can be accurately determined, laying the foundation for subsequent signal tracking and accurate determination of the telegram information in the received signal.

[0139] In order to implement the above embodiments, the present disclosure also proposes a low-orbit satellite signal processing device.

[0140] Fig.10 The present invention is a schematic diagram of the structure of a low-orbit satellite signal processing device provided in an embodiment of the present invention. The low-orbit satellite signal processing device can execute the low-orbit satellite signal processing method in the aforementioned embodiment, wherein the low-orbit satellite signal processing device can be a device such as a user terminal, or can be configured in a device such as a user terminal, and the present invention does not limit this.

[0141] like Fig.10 As shown, the low-orbit satellite signal processing device 1000 includes: a coarse capture module 1010, a compensation module 1020, a fine capture module 1030 and a tracking and decoding module 1040.

[0142] The coarse capture module 1010 is used to perform coarse capture on the received signal to obtain the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal;

[0143] The compensation module 1020 is used to perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal;

[0144] The fine capture module 1030 is used to determine the part of the signal starting from the frame header position in the compensated signal as the target signal, and perform fine capture on the target signal to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal;

[0145] The tracking and decoding module 1040 is used to perform signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal to obtain the telegram information in the received signal.

[0146] As a possible implementation of the embodiment of the present disclosure, the frame structure of the received signal includes a continuous wave signal and a unique codeword; the frame header position of the subframe is represented by the starting position of the unique codeword in the subframe in the received signal;

[0147] The coarse capture module 1010 is used for:

[0148] Detecting whether there is a continuous wave signal in the received signal;

[0149] In the case of detecting the presence of a continuous wave signal, determining that the coarse capture is successful, and determining the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation;

[0150] Based on the starting position of the continuous wave signal in the received signal, the starting position of the unique word code chip in the subframe in the received signal is determined to determine the frame header position of the subframe of the received signal.

[0151] As a possible implementation of the embodiment of the present disclosure, the coarse capture module 1010 is used to:

[0152] According to a preset detection step length, the detection time window is moved along a set direction on the received signal to select multiple detection signals;

[0153] Obtaining the signal-to-noise ratio of each of the multiple detection signals, and performing Fourier transform on the multiple detection signals respectively to obtain the frequency spectrum and power spectrum of the corresponding signals;

[0154] Based on the signal-to-noise ratios of the multiple detection signals, and the frequency spectra and power spectra of the multiple detection signals, detecting whether the multiple detection signals meet the coarse capture condition;

[0155] If the plurality of detection signals satisfy the coarse acquisition condition, it is determined that a continuous wave signal exists in the received signal; and if the plurality of detection signals do not satisfy the coarse acquisition condition, it is determined that no continuous wave signal exists in the received signal.

[0156] As a possible implementation of the embodiment of the present disclosure, the coarse capture condition includes:

[0157] The peak value of the frequency spectrum of each detection signal is higher than the first threshold and the main-sidelobe ratio of the power spectrum is higher than the second threshold, the first difference of adjacent detection signals among the multiple detection signals is lower than the third threshold, and the second difference of adjacent detection signals among the multiple detection signals is lower than the frequency resolution of the received signal;

[0158] Among them, the main-sidelobe ratio of the power spectrum is the ratio of the main lobe maximum value to the sidelobe maximum value of the power spectrum; the first difference is the difference in signal-to-noise ratios of adjacent detection signals; and the second difference is the difference between the frequencies corresponding to the peak values ​​of the frequency spectra of adjacent detection signals.

[0159] As a possible implementation of the embodiment of the present disclosure, the coarse capture module 1010 is used to:

[0160] Determining a starting position of the continuous wave signal in the received signal based on a starting position of a first detection signal among the multiple detection signals in the received signal;

[0161] A first carrier Doppler frequency offset is determined based on a power spectrum of the first detection signal.

[0162] As a possible implementation of the embodiment of the present disclosure, the coarse capture module 1010 is used to:

[0163] Based on the power spectrum of the first detection signal, obtaining the frequency corresponding to the maximum power spectrum amplitude of the first detection signal;

[0164] A first carrier Doppler frequency offset is determined based on the frequency corresponding to the maximum power spectrum amplitude and the frequency resolution of the received signal.

[0165] As a possible implementation of the embodiment of the present disclosure, the precision capture module 1030 is used to:

[0166] Filter the target signal to obtain a baseband signal;

[0167] generating a carrier signal having a carrier frequency based on a pre-stored carrier frequency of a received signal;

[0168] Based on the pre-stored unique codeword and pilot pseudo-random noise code, a target code including the unique codeword and the pilot pseudo-random noise code is generated;

[0169] Carrier signals and target codes are correlated with baseband signals to obtain correlation processing results;

[0170] The correlation processing result is subjected to Fourier transform, and based on the Fourier transform result, the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal are determined.

[0171] As a possible implementation of the embodiment of the present disclosure, the low-orbit satellite signal processing device 1000 further includes:

[0172] The preprocessing module is used to mix and filter the burst signal that reaches the RF front end through the receiver's antenna with the receiver's local oscillator frequency to obtain a mixed signal; perform analog-to-digital conversion on the mixed signal to obtain an intermediate frequency digital signal; and downsample the intermediate frequency digital signal to obtain a received signal.

[0173] The low-orbit satellite signal processing device of the embodiment of the present disclosure obtains the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal by coarsely capturing the received signal, performs frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain the compensated signal, determines the part of the signal starting from the frame header position in the compensated signal as the target signal, and performs fine capture on the target signal to obtain the second carrier Doppler frequency deviation of the target signal and the frame header position of the subframe of the target signal, performs signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal to obtain the telegram information in the received signal, and can quickly and accurately complete the capture of the received signal such as the SPT signal of the low-orbit satellite, and perform signal tracking and channel decoding, so as to quickly and accurately obtain the telegram information in the received signal.

[0174] It should be noted that the above explanation of the embodiment of the method for processing low-orbit satellite signals is also applicable to the apparatus for processing low-orbit satellite signals in this embodiment, and will not be repeated here.

[0175] In order to implement the above embodiments, the present disclosure also proposes an FPGA (Field Programmable Gate Array) chip, including: a processing unit and a storage unit, the storage unit stores instructions that can be executed by the processing unit, and the instructions are executed by the processing unit, so that the processing unit can execute the low-orbit satellite signal processing method proposed in the above embodiments of the present disclosure. The processing unit can be any component unit capable of data processing, and the present disclosure does not limit this.

[0176] Among them, the FPGA chip can be configured in a dedicated signal processing board to execute the low-orbit satellite signal processing method proposed in the embodiment of the present disclosure.

[0177] In addition, the signal processing board may also include an A / D chip (i.e., an analog-to-digital conversion chip) and a storage chip. The storage chip may store data generated when executing the low-orbit satellite signal processing method. The A / D chip may convert analog signals into digital signals for processing by the FPGA chip.

[0178] In order to implement the above embodiments, the present disclosure also proposes an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for processing low-orbit satellite signals proposed in the aforementioned embodiments of the present disclosure.

[0179] In order to implement the above embodiments, the present disclosure also proposes a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable the computer to execute the low-orbit satellite signal processing method proposed in the aforementioned embodiments of the present disclosure.

[0180] In order to implement the above embodiments, the present disclosure further proposes a computer program product. When the instructions in the computer program product are executed by a processor, the method for processing low-orbit satellite signals proposed in the above embodiments of the present disclosure is executed.

[0181] Fig.11 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present disclosure is shown. Fig.11 The electronic device 12 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0182] like Fig.11 As shown, the electronic device 12 is in the form of a general-purpose computing device. The components of the electronic device 12 may include, but are not limited to: one or more processors 16, a memory 28, and a bus 18 connecting different system components (including the memory 28 and the processor 16). The processor 16 may be any component capable of performing data processing, such as a signal processing board in the aforementioned embodiment, including the FPGA chip in the aforementioned embodiment.

[0183] The bus 18 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor or a local bus using any of a variety of bus structures. For example, these architectures include but are not limited to Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MAC) bus, Enhanced ISA bus, Video Electronics Standards Association (VESA) local bus and Peripheral Component Interconnection (PCI) bus.

[0184] The electronic device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the electronic device 12, including volatile and non-volatile media, removable and non-removable media.

[0185] The memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. The electronic device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the storage system 34 may be used to read and write non-removable, non-volatile magnetic media ( Fig.11 Not shown, often called a "hard drive").

[0186] although Fig.11 Not shown in the figure, a disk drive for reading and writing a removable non-volatile disk (e.g., a "floppy disk"), and an optical disk drive for reading and writing a removable non-volatile optical disk (e.g., a compact disc read only memory (hereinafter referred to as: CD-ROM), a digital versatile disc read only memory (hereinafter referred to as: DVD-ROM) or other optical media) may be provided. In these cases, each drive may be connected to the bus 18 via one or more data medium interfaces. The memory 28 may include at least one program product having a set (e.g., at least one) of program modules that are configured to perform the functions of the various embodiments of the present disclosure.

[0187] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in the memory 28, such program modules 42 including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment. The program modules 42 generally perform the functions and / or methods of the embodiments described in the present disclosure.

[0188] The electronic device 12 may also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), one or more devices that enable a user to interact with the electronic device 12, and / or any device that enables the electronic device 12 to communicate with one or more other computing devices (e.g., network card, modem, etc.). Such communication may be performed through an input / output (I / O) interface 22. Furthermore, the electronic device 12 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter 20. Fig.11 As shown, the network adapter 20 communicates with other modules of the electronic device 12 via the bus 18. It should be understood that although Fig.11 Not shown, other hardware and / or software modules may be used in conjunction with the electronic device 12, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0189] The processor 16 executes various functional applications and data processing by running the programs stored in the memory 28, such as implementing the low-orbit satellite signal processing method mentioned in the above embodiment.

[0190] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0191] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0192] Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A method for processing low-orbit satellite signals, characterized in that: The method comprises: Performing coarse capture on a received signal to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal; Based on the first carrier Doppler frequency deviation, the received signal is subjected to frequency and phase compensation to obtain a compensated signal; Determine a portion of the compensated signal starting from the frame header position as a target signal, and perform precise capture on the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal; Based on the Doppler frequency deviation of the second carrier and the frame header position of the subframe of the target signal, signal tracking and channel decoding are performed to obtain the telegram information in the received signal.

2. The method according to claim 1, characterized in that The frame structure of the received signal includes a continuous wave signal and a unique codeword; the frame header position of the subframe is represented by the starting position of the unique codeword in the subframe in the received signal; The coarsely capturing the received signal to obtain the first carrier Doppler frequency deviation of the received signal and the frame header position of the subframe of the received signal includes: Detecting whether the continuous wave signal exists in the received signal; In the case where the continuous wave signal is detected, determining that the coarse capture is successful, and determining the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation; Based on the starting position of the continuous wave signal in the received signal, the starting position of the unique word code chip in the subframe in the received signal is determined to determine the frame head position of the subframe of the received signal.

3. The method according to claim 2, characterized in that The detecting whether there is a continuous wave signal in the received signal comprises: According to a preset detection step length, the detection time window is moved along a set direction on the received signal to select a plurality of detection signals; Obtaining a signal-to-noise ratio of each of the plurality of detection signals, and performing Fourier transform on each of the plurality of detection signals to obtain a frequency spectrum and a power spectrum of the corresponding signal; Based on the signal-to-noise ratio of each of the multiple detection signals, and the frequency spectra and power spectra of the multiple detection signals, detecting whether the multiple detection signals meet the coarse capture condition; If the multiple detection signals satisfy the coarse acquisition condition, it is determined that the continuous wave signal exists in the received signal; and if the multiple detection signals do not satisfy the coarse acquisition condition, it is determined that the continuous wave signal does not exist in the received signal.

4. The method according to claim 3, characterized in that The rough capture conditions include: The peak value of the frequency spectrum of each of the detection signals is higher than a first threshold and the main-sidelobe ratio of the power spectrum is higher than a second threshold, the first difference of adjacent detection signals among the multiple detection signals is lower than a third threshold, and the second difference of adjacent detection signals among the multiple detection signals is lower than the frequency resolution of the received signal; Among them, the main-to-sidelobe ratio of the power spectrum is the ratio of the main lobe maximum value to the side lobe maximum value of the power spectrum; the first difference is the difference in signal-to-noise ratios of adjacent detection signals; and the second difference is the difference between the frequencies corresponding to the peak values ​​of the frequency spectra of the adjacent detection signals.

5. The method according to claim 3, characterized in that: The determining the starting position of the continuous wave signal in the received signal and the first carrier Doppler frequency deviation comprises: Determine a starting position of the continuous wave signal in the received signal based on a starting position of a first detection signal among the multiple detection signals in the received signal; The first carrier Doppler frequency offset is determined based on a power spectrum of the first detection signal.

6. The method according to claim 5, characterized in that The determining the first carrier Doppler frequency offset based on the power spectrum of the first detection signal includes: Based on the power spectrum of the first detection signal, obtaining a frequency corresponding to a maximum power spectrum amplitude of the first detection signal; The first carrier Doppler frequency offset is determined based on the frequency corresponding to the maximum power spectrum amplitude and the frequency resolution of the received signal.

7. The method according to any one of claims 1 to 6, characterized in that The step of performing precise capture on the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal includes: filtering the target signal to obtain a baseband signal; Based on the pre-stored carrier frequency of the received signal, generating a carrier signal having the carrier frequency; Based on the pre-stored unique word code piece and the pilot pseudo-random noise code, generating a target code including the unique word code piece and the pilot pseudo-random noise code; Perform correlation processing on the carrier signal and the target code with the baseband signal to obtain a correlation processing result; Performing Fourier transform on the correlation processing result, and determining the second carrier Doppler frequency offset and the frame header position of the subframe of the target signal based on the Fourier transform result.

8. The method according to any one of claims 1 to 6, characterized in that Before the receiving signal is roughly captured, the method further includes: Mixing and filtering the burst signal that reaches the RF front end through the antenna of the receiver with the local oscillator frequency of the receiver to obtain a mixed signal; Performing analog-to-digital conversion on the mixed signal to obtain an intermediate frequency digital signal; Down-sampling the intermediate frequency digital signal to obtain the received signal.

9. A low-orbit satellite signal processing device, characterized in that: The device comprises: A coarse capture module, used to perform coarse capture on a received signal to obtain a first carrier Doppler frequency deviation of the received signal and a frame header position of a subframe of the received signal; A compensation module, configured to perform frequency and phase compensation on the received signal based on the first carrier Doppler frequency deviation to obtain a compensated signal; A fine capture module, used for determining a portion of the signal starting from the frame header position in the compensated signal as a target signal, and performing fine capture on the target signal to obtain a second carrier Doppler frequency deviation of the target signal and a frame header position of a subframe of the target signal; The tracking and decoding module is used to perform signal tracking and channel decoding based on the second carrier Doppler frequency deviation and the frame header position of the subframe of the target signal to obtain the telegram information in the received signal.

10. An electronic device, comprising: at least one processor; as well as A memory communicatively connected to the at least one processor; characterized in that The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 8.

11. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1 to 8.

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