A method for realizing blind frequency hopping tracking receiver

Abstract

The embodiment of the present application relates to the field of communication technology, and discloses a method for realizing a blind frequency hopping tracking receiver, the method comprising: sampling a target frequency hopping signal based on a detection signal; channelizing the sampled signal based on a preset number of channels and a multiphase filter; performing FFT processing on the signal obtained after the channelization processing and scanning the frequency to determine the frequency peak and the frequency mean, determining the detection threshold value based on the frequency mean, and determining that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold value; performing complex down-conversion processing and low-pass filtering processing on the signal of the channel where the target frequency hopping signal is detected to obtain a filtered signal; performing vector synthesis detection on the filtered signal, and then obtaining the error solution results of the azimuth and elevation angles after phase correction. The method realizes high-quality blind frequency hopping tracking of frequency hopping signals with large bandwidth and high hopping rate.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of communication technology, and in particular to a method for implementing a blind frequency hopping tracking receiver. Background Art

[0002] As an important part of the satellite communication system, the tracking receiver is widely used in mobile platforms such as vehicles, aircraft and ships. It is responsible for controlling the servo motor to adjust the antenna to track the satellite, and can ensure the good quality of satellite communication. Antenna tracking methods can be divided into program guidance and self-tracking. The former requires the known satellite motion trajectory and antenna coordinates, and uses a computer to calculate the direction of the satellite relative to the antenna in real time to perform angle tracking. Therefore, its accuracy is seriously dependent on the accuracy of the ephemeris and sensors. The latter receives the signal transmitted by the satellite to obtain error information, thereby realizing real-time high-precision angle tracking. The process is relatively complex, but it has high accuracy and good real-time performance, and is not dependent on the accuracy of the ephemeris and sensors. It can be seen that the main function of the tracking receiver currently proposed is to complete the angle tracking of beacon signals and common communication signals.

[0003] With the development of satellite communication technology, people have higher requirements in terms of communication quality and anti-interference. Therefore, frequency hopping spread spectrum communication technology with good anti-interference, anti-fading and anti-multipath effects has become an important development direction of satellite communication. However, there are few tracking receivers with the ability to track the angle of frequency hopping signals.

[0004] In existing frequency hopping tracking receivers, the conventional implementation scheme is similar to that of frequency hopping communication receivers, which require known information such as the frequency hopping pattern and hopping rate, and can only be solved and tracked when the transmitter and receiver are synchronized in time. In the absence of information such as the frequency hopping pattern, fixed characteristics and synchronization time, or when synchronization is not completed at the beginning of tracking, how to complete signal blind capture and angle error information solution based on a small amount of known information is one of the difficulties of frequency hopping tracking receivers.

[0005] Frequency hopping signal blind detection technology is widely used in the reconnaissance field, such as broadband reconnaissance aircraft, but there is a lack of mature solutions in the field of frequency hopping tracking receivers, especially for the detection and tracking of large bandwidth and high hopping rate frequency hopping signals, there are still many unsolved difficulties. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a method for implementing a blind frequency hopping tracking receiver, which can complete the detection, tracking and time synchronization of frequency hopping signals in an unknown frequency hopping spectrum and without external clock synchronization. It has good tracking capability for large bandwidth and high hopping rate frequency hopping signals, and greatly improves the blind frequency hopping tracking performance.

[0007] In order to achieve the above-mentioned purpose, an embodiment of the present application proposes a method for realizing a blind frequency hopping tracking receiver, the method comprising the following steps: determining the RF down-conversion parameters and sampling rate of the detection signal based on the carrier frequency conversion center, the overall bandwidth and the instantaneous bandwidth of the target frequency hopping signal, and performing ADC sampling on the target frequency hopping signal based on the detection signal; performing channelization processing on the sampled signal obtained by ADC sampling based on the preset number of channels and the multi-phase filter to obtain a channelized signal; performing FFT processing on the channelized signal and scanning the frequency to determine the frequency peak and the frequency mean, determining the detection threshold based on the frequency mean, judging whether the frequency peak is greater than the detection threshold, and determining that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold; performing complex down-conversion processing on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, and then performing low-pass filtering processing on the complex signal based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal; performing vector synthesis detection on the filtered signal, and then obtaining the error solution results of the azimuth and elevation angles after phase correction.

[0008] An embodiment of the present application 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 a method for implementing a blind frequency hopping tracking receiver as described above.

[0009] An embodiment of the present application further proposes a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for implementing a blind frequency hopping tracking receiver as described above is implemented.

[0010] An implementation method of a blind frequency hopping tracking receiver proposed in an embodiment of the present application first determines the RF down-conversion parameters and sampling rate of the detection signal based on the carrier frequency change center, overall bandwidth and instantaneous bandwidth of the target frequency hopping signal, performs ADC sampling on the target frequency hopping signal based on the detection signal, and then performs channelization processing on the sampled signal obtained by ADC sampling based on a preset number of channels and a multi-phase filter to obtain a channelized signal, then performs FFT processing on the channelized signal and scans the frequency to determine the frequency peak and frequency mean, determines the detection threshold based on the frequency mean, judges whether the frequency peak is greater than the detection threshold, and determines that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold, applies the multi-phase filtering channelization and frequency scanning detection method to the frequency hopping tracking receiver, and can complete channelization processing and signal frequency capture when the signal frequency bandwidth is large. Next, the signal of the channel where the target frequency hopping signal is detected is processed by complex down-conversion to obtain a complex signal, and then the complex signal is low-pass filtered based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal. Complex down-conversion and filtering can greatly improve the signal-to-noise ratio, making the frequency hopping tracking receiver less difficult to implement and improving its performance. Finally, the filtered signal is vector synthesized and detected, and after phase correction, the error solution results of the azimuth and elevation angles are obtained, thereby achieving detection, tracking and time synchronization of the frequency hopping signal in the case of an unknown frequency hopping spectrum and without external clock synchronization, and having good tracking capabilities for frequency hopping signals with a large bandwidth range and fast frequency hopping.

[0011] In some optional embodiments, the method of determining the RF down-conversion parameters and sampling rate of the detection signal based on the carrier frequency conversion center, the overall bandwidth and the instantaneous bandwidth of the target frequency hopping signal includes: obtaining the carrier frequency conversion center F of the target frequency hopping signal RF , overall bandwidth B H , instantaneous bandwidth B 0 And the jump period T H Based on F RF Determine the RF down-conversion parameter F of the detection signal d Among them, F RF -F d Fixed in 4G frequency band; based on B H and B 0 Determine the sampling rate F of the detection signal s , and based on F s Determine the bandwidth B of the detection signal ad Among them, F s ≥B H +B 0 / 2,B ad =F s .

[0012] In some optional embodiments, the preset number of channels is N ch , the order of the polyphase filter is K, K can be divided by N ch Divide into L groups, set the filter coefficient of the polyphase filter to Y, perform channel extraction on Y, and get N ch The filter coefficient Y of the group length L n (x), each set of filter coefficients corresponds to a channel, Y n (x) is expressed by the formula:

[0013] Y n (x) = Y(N ch x+k), k=0,1,2...N ch -1

[0014] Where x represents the sampling point;

[0015] The method of performing channelization processing on the sampled signal obtained by ADC sampling based on the preset number of channels and the multi-phase filter to obtain the signal after channelization processing includes:

[0016] Perform multiphase decomposition on the sampled signal to obtain the multiphase decomposed signal X n (x), X n (x) is expressed by the formula:

[0017] X n (x) = X(N ch x+k), k=0,1,2...N ch -1

[0018] Wherein, X represents the sampling signal;

[0019] X n Each channel of (x) is multiplied by the first exponent e 0 , combined with Y n (x) Filter the channels and multiply the filtering result by the second exponent e 1 , and get the intermediate signal Z n (x), Z n (x) is expressed by the formula:

[0020] Z n (x) = [X n (x)·e 0 *Y n (x)]·e 1

[0021] If the channel type is odd, then e 0 =(-1) x , If the channel type is even, then e 0 =1,e1 =(-1) x ;

[0022] Finally, Z n (x)N ch Point parallel DFT processing is performed to obtain the signal S after channelization processing n (x), S n (x) is expressed by the formula:

[0023] S n (x) = DFT[Z n (x)]

[0024] Here, DFT(·) represents DFT processing.

[0025] In some optional embodiments, performing FFT processing on the signal after channelization processing and scanning the frequency, determining the frequency peak and the frequency mean, determining the detection threshold based on the frequency mean, judging whether the frequency peak is greater than the detection threshold, and determining that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold, includes: based on T H Set the local detection period and the interception length N fft Each local detection cycle intercepts N fft data, in parallel ch Road N fft FFT processing of points; where N fft ≤T H ·F s / N ch ; Scan all N ch The frequency of the FFT processing result of the path is used to determine the frequency peak P fft and frequency mean M fft , for M fft Multiply by the preset first coefficient G to obtain the detection threshold value P th , P th =G·M fft ; Judge P fft Is it greater than P th , if P fft >P th , it is determined that the target frequency hopping signal is detected, P fft ≤P th , it is determined that the target frequency hopping signal is not detected.

[0026] In some optional embodiments, for each local detection cycle, N fft The first half and the second half are evenly divided. For the current local detection cycle, N are intercepted in each channel. fft data, in parallelch Road N fft While performing FFT processing of the points, the method also includes: obtaining the current environmental noise, judging whether the current environmental noise is greater than a preset noise threshold; if the current environmental noise is less than or equal to the preset noise threshold, using a frequency peak detection method, performing FFT processing on the data of the first half and the data of the second half respectively and detecting the peak value to estimate the energy value; if the current environmental noise is greater than the preset noise threshold, using a time domain energy detection method, square and sum the data of the first half and the data of the second half respectively to calculate the energy value; comparing the energy value of the first half and the energy value of the second half, if the energy value of the first half is greater than the energy value of the second half, offsetting the next local detection cycle to the first half by a preset step number N step If the energy value of the first half is less than the energy value of the second half, the next local detection cycle is shifted to the second half by N step , if the energy value of the first half is equal to the energy value of the second half, no offset processing is performed. In the initial state, the phase of the hopping period of the target frequency hopping signal and the local detection period cannot be aligned with each other with a high probability, so estimation and correction are required. Therefore, this application needs to fft The energy of the front and back halves is compared to shift the local detection period, thereby improving the detection and tracking effect of the frequency hopping signal.

[0027] In some optional embodiments, if it is determined that the target frequency hopping signal is not detected in the local detection cycle, a preset waiting time T is waited before the next local detection cycle. wait ; Among them, T wait <T H . T wait The design can prevent the situation where the target frequency hopping signal cannot be detected for a long time and avoid continuous missed detection.

[0028] In some optional embodiments, complex down-conversion processing is performed on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, which is implemented by the following formula:

[0029] Z signal (x) = Z find (x)·[cos(ω 1 t)-j·sin(ω 1 t)]

[0030] Among them, Z find (x) represents the signal of the channel where the target frequency hopping signal is detected, and Z signal (x) represents a complex signal, ω 1 It represents the signal peak frequency obtained by frequency scanning after channelization processing, that is, the estimated Z find (x) Signal center frequency.

[0031] In some optional embodiments, the error calculation results of the azimuth angle and the elevation angle are expressed by the following formula:

[0032]

[0033] Among them, θ and Indicates the azimuth error and elevation error information, α 1 Represents the phase value of the sum channel, α 2 represents the phase value of the difference channel, β represents the phase difference calibration value, U A ′ represents the error solution result of the azimuth angle, U E ′ represents the error solution result of the pitch angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0035] Figure 1 It is a flow chart of a method for implementing a blind frequency hopping tracking receiver proposed in an embodiment of the present application;

[0036] Figure 2 It is a schematic diagram of performing channelization processing on a sampling signal obtained by ADC sampling based on a preset number of channels and a multi-phase filter in an embodiment of the present application;

[0037] Figure 3 is a schematic diagram of a channelized channel arrangement provided in one embodiment of the present application;

[0038] Figure 4 is a schematic diagram of a channelized simulation result provided in an embodiment of the present application;

[0039] Figure 5 is a schematic diagram of a simulation result of a frequency scan provided in an embodiment of the present application;

[0040] Figure 6 is a schematic diagram of an angle error solution result provided in an embodiment of the present application;

[0041] Figure 7 It is a structural schematic diagram of an electronic device provided by another embodiment of the present application. DETAILED DESCRIPTION

[0042] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0043] In order to more clearly illustrate the technical solution of the present application, several mature signal tracking technologies are first introduced here.

[0044] 1) Synchronous acquisition and tracking scheme of frequency hopping pattern

[0045] Similar to the synchronization method of frequency hopping receivers, this technology requires a known frequency hopping pattern and time synchronization to complete acquisition and tracking. The reference time is obtained through the external input synchronization time signal, and the signal delay is estimated according to the target distance to obtain the current frequency point time. If the time synchronization accuracy is not enough, a frequency hopping code phase search is required. The current frequency hopping frequency can be calculated based on the frequency hopping pattern stored in the receiver, thereby completing the frequency hopping frequency synchronization.

[0046] 2) Capture and tracking scheme based on signal characteristics

[0047] When the fixed characteristics of the frequency hopping signal are determined, for example, if the frequency point of 0.1ms is known every 10ms, the tracking process can be performed based on the signal of this known frequency point. The fixed frequency point value is determined by external input, and the fixed intermediate frequency signal is detected during the process. If the signal is detected, the angle error is solved, otherwise wait.

[0048] 3) Frequency hopping signal blind capture solution

[0049] When the signal frequency range and signal hopping rate are known, if the frequency hopping pattern and synchronization time information are unknown, signal blind detection and angular error solution are required. This situation is similar to the research in the field of frequency hopping signal reconnaissance. Signal reconnaissance technology mainly studies how to detect frequency hopping signals in the absence of specific parameters. The types of conventional reconnaissance digital receivers include FFT receivers and channelized receivers, and conventional algorithms include autocorrelation technology, time-frequency analysis, and spatial spectrum estimation. However, there are currently few solutions applied in the field of tracking receivers. The conventional solutions are as follows: For frequency hopping signals with smaller bandwidths, the conventional solution is to directly perform energy detection or cross-correlation detection within the bandwidth range. The detection solutions include sum-difference cross-correlation detection, FFT processing peak detection, etc. After completing signal detection, the sum-difference signal amplitude information is obtained through vector synthesis detection or envelope detection, thereby solving the angular error information; for frequency hopping signals with larger bandwidths, the conventional solution is to set the detection bandwidth range. The detection bandwidth is set to a smaller range of processable frequencies, waiting for the frequency hopping signal to fall into the detection bandwidth range. If a valid signal is detected, the signal data is intercepted for vector synthesis detection or envelope detection to obtain the amplitude information of the sum and difference signals, thereby solving the angle error information. If no valid signal is detected within the detection bandwidth, the data segment is discarded.

[0050] It can be seen that both conventional synchronous capture and tracking schemes and capture and tracking schemes based on signal characteristics require more known information and accurate time synchronization information. However, due to factors such as actual hardware system errors and communication delays, in the initial stage of tracking, the time synchronization accuracy is poor, and frequency hopping synchronization cannot be completed immediately. Error correction is required, and the correction time is long. At the same time, during the correction period, the tracking effect is very poor due to the failure to complete frequency hopping synchronization. If the target and the antenna are in a state of relative motion, as the antenna pointing error becomes larger, the received signal signal-to-noise ratio is lower, and it is more difficult to complete frequency hopping synchronization. If synchronization cannot be completed for a long time, tracking failure may occur. Therefore, these two schemes are not suitable for situations where the frequency hopping pattern and time synchronization information are unknown, and the tracking effect is very poor before frequency hopping synchronization.

[0051] Conventional blind capture schemes have a small processing bandwidth and cannot achieve full bandwidth capture for frequency hopping signals with a large bandwidth range. Although the frequency hopping tracking scheme with fixed detection of partial bandwidth is simple to implement, it only detects part of the bandwidth, so there is a certain signal-to-noise ratio loss and poor tracking performance. In addition, considering the randomness of frequency hopping signals, it is possible that no signal falls into the detection frequency band for a long time, which may cause system tracking delays.

[0052] In order to solve the technical problem of how to complete blind signal capture and angle error information solution based on a small amount of known information in the absence of information such as frequency hopping patterns, fixed characteristics and synchronization time, or when synchronization is not completed at the beginning of tracking, an embodiment of the present application proposes an implementation method of a blind frequency hopping tracking receiver, which is applied to a processor. The implementation details of the implementation method of a blind frequency hopping tracking receiver proposed in this embodiment are specifically described below. The following content is only the implementation details provided for ease of understanding and is not necessary for the implementation of this solution.

[0053] The process of implementing a method for blind frequency hopping tracking receiver proposed in this embodiment can be as follows: Figure 1 As shown, including:

[0054] Step 101, based on the carrier frequency conversion center, overall bandwidth and instantaneous bandwidth of the target frequency hopping signal, determine the RF down-conversion parameters and sampling rate of the detection signal, and perform ADC sampling on the target frequency hopping signal based on the detection signal.

[0055] In the specific implementation, the processor first needs to determine the carrier frequency change center, overall bandwidth and instantaneous bandwidth of the target frequency hopping signal, and then determine the RF down-conversion parameters and sampling rate of the detection signal based on the carrier frequency change center, overall bandwidth and instantaneous bandwidth of the target frequency hopping signal, and finally perform ADC sampling on the target frequency hopping signal based on the detection signal.

[0056] In one example, the processor first needs to obtain the known carrier frequency conversion center F of the target frequency hopping signal according to the design requirements. RF , overall bandwidth B H (i.e., the range of carrier frequency change), instantaneous bandwidth B 0 And the jump period T H . Because B H Much larger than B 0 , so the signal frequency range of the target frequency hopping signal can be simplified to (F RF -B H / 2,F RF +B H / 2). The processor determines F RF After that, based on F RF Determine the RF down-conversion parameter F of the detection signal d , where F RF -F d Fixed in the 4G frequency band, the frequency range of the intermediate frequency signal obtained after sampling can be expressed as (F RF -F d -B H / 2,F RF -F d +B H / 2). The processor determines BH and B 0 After that, based on B H and B 0 Determine the sampling rate F of the detection signal s , F s ≥B H +B 0 / 2, and based on F s Determine the bandwidth B of the detection signal ad , B ad =F s , the frequency range of the detection signal can be expressed as (-F s / 2,F s / 2). Such parameter settings and parameter selections can satisfy the bandpass sampling theorem.

[0057] Step 102: Based on a preset number of channels and a multi-phase filter, channelization processing is performed on the sampled signal obtained by ADC sampling to obtain a channelized signal.

[0058] In a specific implementation, after completing ADC sampling, the processor may perform channelization processing on the sampling signal obtained by ADC sampling based on a preset number of channels and a multi-phase filter to obtain a signal after channelization processing.

[0059] In one example, the preset number of channels is N. ch , N ch is an integer greater than 1. The polyphase filter is composed of multiple low-pass filters. The filtering parameters of the polyphase filter can be based on N ch Calculated, for example, the order of the polyphase filter is K, K can be divided by N ch Divided into L groups, the normalized passband frequency can be set to 2 / N ch , other parameters such as stopband frequency, stopband attenuation, etc. can be selected with appropriate values.

[0060] For non-ideal low-pass filters, the transition band bandwidth cannot be infinitely small, so there must be energy leakage in adjacent channels. Therefore, the passband frequency can be adjusted appropriately to reduce energy leakage by reducing the passband frequency. However, when the passband frequency is too small, a detection blind spot will appear, so the filter parameters need to be measured according to the use requirements. Considering that spectrum leakage has little effect on the corner error solution, while the blind spot has a greater impact on the solution result, the spectrum leakage can be minimized while ensuring that there is no blind spot.

[0061] Assume that the filter coefficient of the polyphase filter is Y (also called the filter coefficient of the low-pass filter), and perform polyphase decomposition on Y, that is, extract according to the channel, to obtain N ch The filter coefficient Y of the group length L n (x), each set of filter coefficients corresponds to a channel, Yn (x) is expressed by the formula:

[0062] Y n (x) = Y(N ch x+k), k=0,1,2...N ch -1

[0063] Where x represents the sampling point.

[0064] Depending on whether the input signal is a real signal or a complex signal, and whether the channel type is odd or even, the channelization efficiency structure implemented by the polyphase filter is also different. Since the sum and difference signals of the tracking receiver are both complex signals, it is only necessary to Figure 2 The channelization principle shown in Figure 3 The example uses the channel type, and the processing process is as follows:

[0065] The processor first performs multiphase decomposition on the sampled signal to obtain the multiphase decomposed signal X n (x), X n (x) can be expressed by the formula:

[0066] X n (x) = X(N ch x+k), k=0,1,2...N ch -1

[0067] Where X represents the sampling signal. After the multi-phase decomposition is completed, the data frequency of a single channel is reduced to F s / N ch , all subsequent processing is performed at this lower frequency.

[0068] Processor to X n Each channel of (x) is multiplied by the first exponent e 0 , combined with Y n (x) Filter the channels and multiply the filtering result by the second exponent w 1 , and get the intermediate signal Z n (x), Z n (x) is expressed by the formula:

[0069] Z n (x) = [X n (x)·e 0 *Y n (x)]·e 1

[0070] If the channel type is odd, then e 0 =(-1) x , If the channel type is even, then e 0 =1,e1 =(-1) x .

[0071] Finally, the processor Z n (x)N ch Point parallel DFT processing is performed to obtain the signal S after channelization processing n (x), S n (x) can be expressed by the formula:

[0072] S n (x) = DFT[Z n (c)]

[0073] Here, DFT(·) represents DFT processing.

[0074] The effect of multi-phase filtering channelization can be referred to Figure 4 , Figure 4 From top to bottom in the figure are channels 1 to 4, and the ordinate is the absolute value of the complex signal output by the channel, which can be regarded as the signal amplitude. Figure 4 It can be seen that the signal changes frequency every 50us, the channel corresponding to the frequency has signal output, and other channels have basically no signal or a small amount of energy leakage.

[0075] Step 103, perform FFT processing on the signal after channelization processing and scan the frequency, determine the frequency peak and the frequency mean, determine the detection threshold based on the frequency mean, judge whether the frequency peak is greater than the detection threshold, and determine that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold.

[0076] In a specific implementation, after obtaining the signal after channelization processing, the processor needs to perform FFT processing on the signal after channelization processing and scan the frequency, determine the frequency peak and frequency mean based on the frequency scanning results of all channels, determine the detection threshold value based on the frequency mean, judge whether the frequency peak is greater than the detection threshold value, and determine that the target frequency hopping signal is detected when the frequency peak is greater than the detection threshold value.

[0077] In one example, after obtaining the signal after channelization processing, the processor immediately adjusts the frequency hopping period T of the target frequency hopping signal based on the hopping period T of the target frequency hopping signal. H Set the local detection period T local , and set the interception length N fft , each T local In each channel, a length of N is intercepted fft Data, N fft ≤T H ·F s / N ch , and N ch Road N fftFFT processing of points. fft Set to a power of 2 and not more than the number of data points in a transition cycle. local After that, the processor needs to scan all N ch The frequency scan result is as follows: Figure 5 As shown, from top to bottom they are channel 1 to channel 4, from Figure 5 As can be seen in the figure, when the jump time is estimated accurately, if there is a signal input, the signal spectrum peak of the corresponding frequency can be clearly seen from the spectrum, and the detection result can be determined by comparing the peak point with the threshold size. ch After the frequency of the FFT processing result of the path, it is necessary to determine the frequency peak P fft and frequency mean M fft , for M fft Multiply by the preset first coefficient G to obtain the detection threshold value P th , P th =G·M fft , then judge P fft Is it greater than P th , if P fft >P th , it is determined that the target frequency hopping signal is detected, P fft ≤P th , it is determined that the target frequency hopping signal is not detected.

[0078] In one example, the processor needs to estimate the hopping time while performing signal detection. This is because in the initial state, the hopping period of the target frequency hopping signal and the phase of the local detection period are unlikely to be aligned, so estimation and correction are required. The hopping time estimation can be achieved through a cross-correlation algorithm or an energy detection algorithm.

[0079] Taking the energy detection algorithm as an example, for each local detection cycle, the processor will fft For the current local detection cycle, the processor intercepts N fft data, in parallel ch Road N fftWhile performing FFT processing on the points, it is also necessary to obtain the current environmental noise and determine whether the current environmental noise is greater than the preset noise threshold. If the current environmental noise is less than or equal to the preset noise threshold, the frequency peak detection method is used to perform FFT processing on the data in the first half and the data in the second half respectively and detect the peak value to estimate the energy value; if the current environmental noise is greater than the preset noise threshold, the time domain energy detection method is used to perform square summation on the data in the first half and the data in the second half respectively to calculate the energy value, compare the energy value in the first half with the energy value in the second half, and if the energy value in the first half is greater than the energy value in the second half, the next local detection cycle is offset to the first half by the preset step number N. step If the energy value of the first half is less than the energy value of the second half, the next local detection cycle is shifted to the second half by N step If the energy value of the first half is equal to the energy value of the second half, no offset processing is performed. step The value of should not be too large. For example, if N fft =2048, then N step Can be set to N step =N fft / 200.

[0080] In one example, when the target frequency hopping signal changes from nothing to something, if the phase difference between the local detection cycle and the hopping cycle of the input signal frequency is too large, and the clock is not edge-adjusted, the signal spectrum peak may be too small, resulting in the situation of no signal detection always occurring, and a continuous missed detection error may occur. To avoid this situation, if it is determined that the target frequency hopping signal is not detected in the local detection cycle, the processor needs to wait for a preset waiting time T before the next local detection cycle. wait , T wait <T H , ensuring that the phase of each local detection cycle changes. T wait The value of should not be too small and should not exceed T H , if T wait If the value is too small, the compensation time step of each local detection cycle is too small, and a situation where missed detection can only be successfully detected after a period of time may occur, resulting in a longer delay in frequency hopping signal detection. wait If the value is too large, the compensation time accuracy of each local detection cycle will be too low, and multiple cycles of continuous missed detection may occur.

[0081] Step 104, performing complex down-conversion processing on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, and then performing low-pass filtering processing on the complex signal based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal.

[0082] In a specific implementation, after completing signal detection, the processor can perform complex down-conversion processing on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, and then perform low-pass filtering processing on the complex signal based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal. The purpose of low-pass filtering is to improve the signal-to-noise ratio of the signal as much as possible. Therefore, it is necessary to select a suitable passband frequency of the low-pass filter based on the instantaneous bandwidth of the target frequency hopping signal. In order to improve the signal-to-noise ratio, the passband frequency should be selected as small as possible.

[0083] In one example, the processor performs complex down-conversion processing on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, which can be implemented by the following formula:

[0084] Z signal (x) = Z find (x)·[cos(ω 1 t)-j·sin(ω 1 t)]

[0085] Among them, Z find (x) represents the signal of the channel where the target frequency hopping signal is detected, and Z signal (x) represents a complex signal, ω 1 It represents the signal peak frequency obtained by frequency scanning after channelization processing, that is, the estimated Z find (x) Signal center frequency.

[0086] Step 105, performing vector synthesis detection on the filtered signal, and then performing phase correction to obtain error calculation results of the azimuth angle and the pitch angle.

[0087] In a specific implementation, the processor performs low-pass filtering on the complex signal based on the instantaneous bandwidth of the target frequency-hopping signal. After obtaining the filtered signal, the processor can perform vector synthesis detection on the filtered signal, and then obtain the error solution results of the azimuth and elevation angles after phase correction.

[0088] In one example, for a conventional digital transmission type broadband frequency hopping signal, a single pulse antenna receives the signal and passes through a feed source and a comparator, and the output signal can be expressed as:

[0089] S ∑ =C(t)·E I ·cos(ω·t+α)

[0090] S Δaz =C(t)·(μA·E Δ )·cos(ω·t+α)

[0091] S Δel =C(t)·(μE·E Δ )·cos(ω·t+α)

[0092] Where C(t) represents the modulation data, E I 、μA·E Δ 、μE·E Δ are the signal energies of the sum path, azimuth difference path, and elevation difference path, respectively. ω is the carrier frequency of the received RF signal, and α is the initial phase of the received sum and difference signal. According to the principle of the amplitude comparison single pulse algorithm, E I , e Δ represents the signal energy and E I =e Δ , μ is the difference slope, A and E represent the azimuth and elevation angle error information.

[0093] For the dual-channel single pulse system, the two difference signals need to be orthogonally synthesized:

[0094] S Δ =C(t)·μE Δ ·[A·cos(ωt+α)+E·sin(ωt+α)]

[0095] The sum and difference signals are then converted into low-frequency complex signals through analog down-conversion, and then sampled by ADC, digitally channelized, and digitally down-converted, which will reduce the signal carrier frequency and inevitably change the phase and amplitude of the sum and difference IQ channels. Therefore, the processed sum and difference channels can be expressed as the following formula:

[0096] I ∑ =C(t)·E I∑ ·cos(ω 0 t+α 1 )

[0097] Q ∑ =C(t)·E Q∑ ·sin(ω 0 t+α 3 )

[0098] I Δ =C(t)·E IΔ ·μ(A·cos(ω 0 t+α 2 )+E·sin(ω 0 t+α 2 ))

[0099] Q Δ =C(t)·E QΔ ·μ(A·sin(ω 0 t+α 4 )+E·cos(ω 0 t+α 4 ))

[0100] Among them, ω0 is the carrier frequency of the signal after down-conversion, α 1 , α 2 , α 3 , α 4 Represent the phase values ​​of the sum and difference channels respectively. I∑ 、E Q∑ 、μE IΔ 、μE QΔ Represent the signal amplitude of the sum and difference channels respectively.

[0101] To facilitate subsequent derivation, the complex difference signal is transformed through the trigonometric function formula, and we can get:

[0102]

[0103]

[0104] in, Therefore, the angle error information A and E can be obtained by θ and express.

[0105] The processor performs vector synthesis detection processing on the sum and difference signals, and the formula is as follows:

[0106] (Q+j·I)=(I Δ +j·Q Δ )·(Q ∑ +j·I ∑ )=(I Δ Q ∑ -Q Δ I ∑ )+j·(I Δ I ∑ +Q Δ Q ∑ )

[0107] For a dual-channel tracking receiver, the I and Q phase difference of the complex channel during processing is stabilized to 90°, that is, α 1 =α 3 , α 2 =α 4 ; The signal amplitudes of the complex channels are equal, that is, E I∑ =E Q∑ =E ∑ , E IΔ =E QΔ =E Δ , then E I∑ =E IΔ =E Q∑ =E QΔ =E sig For digital signals, C 2 (t)=1.

[0108] Therefore, the vector detection result can be simplified as:

[0109]

[0110] Dividing it by the square of the sum signal, we get:

[0111]

[0112] If the phase error of the sum and difference signals is zero, then α 1 -α 2 =0, the azimuth and elevation angle error processing results are:

[0113]

[0114] By multiplying the error voltage of the antenna drive motor, the signal processing process of the tracking receiver system is completed. The simulation results are as follows: Figure 6 shown.

[0115] However, for dual-channel tracking receivers, the main system error is the relative phase error between the sum and difference channels. In other words, in most cases in actual engineering, the phase difference of the sum and difference signals is difficult to be zero, that is, α 1 -α 2 ≠0, which leads to inaccurate final processing results.

[0116] At this time, the processor needs to use phase correction to accurately correct the phase difference to zero. Common phase correction schemes include zero point phase correction, fast phase correction with deviation, etc. Common compensation schemes include sum and difference delay compensation and result phase compensation. Here is a relatively simple method for solving the result phase compensation:

[0117]

[0118] Or it can be expressed in complex multiplication form as follows:

[0119] (U E ′+j·U A ′)=(cosβ+j·sinβ)·(E+j·A)

[0120] When the phase calibration is accurate, β = α 2 -α 1 .

[0121] Then the solution result is:

[0122]

[0123] Among them, θ and Indicates the azimuth error and elevation error information, α 1Represents the phase value of the sum channel, α 2 represents the phase value of the difference channel, β represents the phase difference calibration value, U A ′ represents the error solution result of the azimuth angle, U E ′ represents the error solution result of the pitch angle.

[0124] In this embodiment, the RF down-conversion parameters and sampling rate of the detection signal are determined based on the carrier frequency conversion center, overall bandwidth and instantaneous bandwidth of the target frequency hopping signal, and the target frequency hopping signal is sampled by ADC based on the detection signal, and then the sampled signal obtained by ADC sampling is channelized based on the preset number of channels and multi-phase filter, and then the signal after channelization is processed by FFT and the frequency is scanned to determine the frequency peak and the frequency mean, and the detection threshold is determined based on the frequency mean, and it is judged whether the frequency peak is greater than the detection threshold, and when the frequency peak is greater than the detection threshold, it is determined that the target frequency hopping signal is detected, and the multi-phase filtering channelization and frequency scanning detection method are applied to the frequency hopping tracking receiver, which can complete the channelization processing and signal frequency capture when the signal frequency bandwidth is large. Next, the signal of the channel where the target frequency hopping signal is detected is processed by complex down-conversion to obtain a complex signal, and then the complex signal is processed by low-pass filtering based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal, and the complex down-conversion and low-pass filtering can well improve the signal-to-noise ratio, so that the frequency hopping tracking receiver is less difficult to implement and the performance is improved. Finally, the filtered signal is subjected to vector synthesis detection and phase correction to obtain the error solution results of the azimuth and elevation angles, thereby realizing the detection, tracking and time synchronization of the frequency hopping signal in the absence of an unknown frequency hopping spectrum and external clock synchronization. It has a good tracking capability for frequency hopping signals with large bandwidth and fast frequency hopping.

[0125] The step division of the above methods is only for clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this application; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this application.

[0126] Another embodiment of the present application provides an electronic device, such as Figure 7 As shown, it includes: at least one processor 201; and a memory 202 that is communicatively connected to the at least one processor 201; wherein the memory 202 stores instructions that can be executed by the at least one processor 201, and the instructions are executed by the at least one processor 201 so that the at least one processor 201 can execute an implementation method of a blind frequency hopping tracking receiver in the above-mentioned embodiments.

[0127] Among them, the memory and the processor are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors and memories together. The bus can also connect various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor.

[0128] The processor is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory can be used to store data used by the processor when performing operations.

[0129] Another embodiment of the present application provides a computer-readable storage medium storing a computer program, which implements the above method embodiment when executed by a processor.

[0130] That is, those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as: ROM), random access memory (Random Access Memory, referred to as: RAM), disk or optical disk and other media that can store program codes.

[0131] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A method for implementing a blind frequency hopping tracking receiver, characterized in that: include: Determine the RF down-conversion parameters and sampling rate of the detection signal based on the carrier frequency conversion center, the overall bandwidth and the instantaneous bandwidth of the target frequency hopping signal, and perform ADC sampling on the target frequency hopping signal based on the detection signal; Based on a preset number of channels and a multi-phase filter, a sampling signal obtained by ADC sampling is subjected to channelization processing to obtain a signal after channelization processing; Performing FFT processing on the signal after channelization processing and scanning the frequency, determining a frequency peak and a frequency mean, determining a detection threshold based on the frequency mean, judging whether the frequency peak is greater than the detection threshold, and determining that a target frequency hopping signal is detected when the frequency peak is greater than the detection threshold; Performing complex down-conversion processing on the signal of the channel where the target frequency hopping signal is detected to obtain a complex signal, and then performing low-pass filtering processing on the complex signal based on the instantaneous bandwidth of the target frequency hopping signal to obtain a filtered signal; The filtered signal is subjected to vector synthesis detection and then phase correction to obtain the error calculation results of the azimuth and elevation angles. The preset number of channels is , the order of the polyphase filter is , Can be Divided into The filter coefficients of the polyphase filter are ,right Channel extraction can be performed to obtain The group length is The filter coefficient , each set of filter coefficients corresponds to a channel, It is expressed by the formula: ； in, Indicates the sampling point; The method of performing channelization processing on the sampled signal obtained by ADC sampling based on the preset number of channels and the multi-phase filter to obtain the signal after channelization processing includes: Perform multiphase decomposition on the sampled signal to obtain the multiphase decomposed signal , It is expressed by the formula: ； in, represents the sampling signal; right Multiply each channel by the first exponent , combined with Filter the channels and multiply the filtering result by the second exponent , and get the intermediate signal , It is expressed by the formula: ； Among them, if the channel type is odd, then , , if the channel type is even, then , ; Last pair conduct Point-wise parallel DFT processing to obtain the signal after channelization processing , It is expressed by the formula: ； in, Indicates DFT processing.

2. The method for implementing a blind frequency hopping tracking receiver according to claim 1, characterized in that: The method of determining the radio frequency down-conversion parameters and sampling rate of the detection signal based on the carrier frequency conversion center, the overall bandwidth and the instantaneous bandwidth of the target frequency hopping signal includes: Get the carrier frequency change center of the target frequency hopping signal , Overall bandwidth , instantaneous bandwidth and transition cycle ; based on Determine the RF down-conversion parameters of the detection signal ;in, Fixed to 4G frequency band; based on and Determine the sampling rate of the detection signal , and based on Determine the bandwidth of the detection signal ;in, , .

3. The method for implementing a blind frequency hopping tracking receiver according to claim 2, characterized in that: The method of performing FFT processing on the signal after channelization processing and scanning the frequency, determining a frequency peak value and a frequency mean value, determining a detection threshold value based on the frequency mean value, judging whether the frequency peak value is greater than the detection threshold value, and determining that a target frequency hopping signal is detected when the frequency peak value is greater than the detection threshold value, includes: based on Set the local detection period and set the interception length , each local detection cycle intercepts data in parallel Road FFT processing of points; among them, ; Scan All The frequency of the FFT processing result of the path is used to determine the frequency peak and frequency mean ,right Multiply by the preset first coefficient Get the detection threshold , ; judge Is it greater than ,like , it is determined that the target frequency hopping signal is detected, , it is determined that the target frequency hopping signal is not detected.

4. The method for implementing a blind frequency hopping tracking receiver according to claim 3, characterized in that: For each local detection cycle, The first half and the second half are evenly divided. For the current local detection cycle, each channel is intercepted data in parallel Road While performing FFT processing on the points, the method further comprises: Obtain the current environmental noise and determine whether the current environmental noise is greater than a preset noise threshold; If the current environmental noise is less than or equal to the preset noise threshold, the frequency peak detection method is used to perform FFT processing on the first half of the data and the second half of the data respectively and detect the peak value to estimate the energy value; If the current environmental noise is greater than the preset noise threshold, the time domain energy detection method is used to square and sum the first half of the data and the second half of the data to calculate the energy value; Compare the energy value of the first half with the energy value of the second half. If the energy value of the first half is greater than the energy value of the second half, the next local detection cycle is shifted to the first half by the preset step number. If the energy value of the first half is less than the energy value of the second half, the next local detection cycle is shifted to the second half. , if the energy value of the first half is equal to the energy value of the second half, no offset processing is performed.

5. The method for implementing a blind frequency hopping tracking receiver according to claim 4, characterized in that: If the target frequency hopping signal is not detected in the local detection cycle, wait for the preset waiting time before the next local detection cycle. ;in, .

6. The method for implementing a blind frequency hopping tracking receiver according to claim 1, characterized in that: The signal of the channel where the target frequency hopping signal is detected is subjected to complex down-conversion processing to obtain a complex signal, which is achieved by the following formula: ； in, A signal indicating the channel in which the target frequency hopping signal is detected, represents a complex signal, Indicates the signal peak frequency obtained by frequency scanning after channelization processing, that is, the estimated Signal center frequency.

7. The method for implementing a blind frequency hopping tracking receiver according to claim 1, characterized in that: The error calculation results of azimuth and elevation angles are expressed by the following formula: ； ； in, and Indicates azimuth error and elevation error information, Indicates the phase value of the sum channel, represents the phase value of the difference channel, Indicates the phase difference calibration value, represents the error solution result of the azimuth angle, Indicates the error solution result of the pitch angle.

8. An electronic device, characterized in that: include: at least one processor; as well as, 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 a method for implementing a blind frequency hopping tracking receiver as described in any one of claims 1 to 7.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, a method for implementing a blind frequency hopping tracking receiver according to any one of claims 1 to 7 is implemented.

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