Angle tracking and measurement anti-interference method and device for unmanned aerial vehicle frequency hopping system

Abstract

The present application relates to an anti-interference method and device for angle tracking and measurement of a frequency hopping system of an unmanned aerial vehicle, which relates to the field of signal processing. It includes: using the sum-difference network system of the receiving end to obtain the first sum signal and the first difference signal of the first single pulse signal; using the sum-difference network system of the receiving end to obtain the second sum signal and the second difference signal of the second single pulse signal; the frequencies of the first single pulse signal and the second single pulse signal are different; the first reference sequence of the receiving end is correlated with the first sum signal to obtain the first phase shift generated by the first single pulse signal at the receiving end; the second reference sequence of the receiving end is correlated with the second sum signal to obtain the second phase shift generated by the second single pulse signal at the receiving end; the difference between the first phase shift and the second phase shift is used as a correction value to correct the random phase shift of the first signal after the second sum signal and the second difference signal are mixed. The present application has the technical effect of being able to measure angles for frequency hopping signals.

Description

Technical Field

[0001] The present application relates to the field of signal processing, and in particular to a method for anti-interference of angle tracking and measurement of a frequency hopping system of an unmanned aerial vehicle, and a device for anti-interference of angle tracking and measurement of a frequency hopping system of an unmanned aerial vehicle. Background Art

[0002] At present, single pulse angle measurement is a commonly used angle measurement method in radar. It uses multiple antennas to receive echo signals at the same time and obtains the angle position information of the target by comparing the amplitude or phase of the echo signals. The single pulse angle measurement method only needs one echo pulse to determine the angle error information of the target. It is simple to operate, has strong real-time performance, and high angle measurement accuracy. Therefore, it is widely used in modern phased array radar systems and has important application value in radar, sonar, wireless communication and other fields.

[0003] The mobile communication channel environment is bad, and various interferences will come unintentionally. In order to resist the interference of certain frequencies, the use of frequency hopping technology is one of the effective methods; then how to measure the angle of the frequency hopping signal is a technical problem that needs to be solved urgently.

[0004] With respect to the above-mentioned related technologies, the inventors found that there are at least the following problems in the related technologies: how to use a single pulse to measure angles in a frequency hopping state; since each frequency jump will introduce a random initial phase, resulting in insufficient angle measurement accuracy; and the measured angle jitters with noise. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides an anti-interference method for angle tracking and measurement of a UAV frequency hopping system, and an anti-interference device for angle tracking and measurement of a UAV frequency hopping system.

[0006] This application provides an anti-interference method for angle tracking measurement of a UAV frequency hopping system, which adopts the following technical solutions:

[0007] In a first aspect, a method for anti-interference of angle tracking measurement of a UAV frequency hopping system is provided, comprising:

[0008] Acquire a first sum signal and a first difference signal of the first single pulse signal by using a sum-difference network system at a receiving end;

[0009] A second sum signal and a second difference signal of a second single pulse signal are obtained by using a sum-difference network system at a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different;

[0010] Performing a correlation operation on a first reference sequence at a receiving end and a first sum signal to obtain a first phase shift generated by the first single pulse signal at the receiving end;

[0011] Performing correlation operation on the second reference sequence at the receiving end and the second sum signal to obtain a second phase shift generated by the second single pulse signal at the receiving end;

[0012] Using the difference between the first phase shift and the second phase shift as a correction value to correct the random phase shift of the first signal after the second sum signal and the second difference signal are mixed, so as to obtain a first mixed signal;

[0013] The first mixed signal is subjected to envelope detection to filter out-of-band noise, DC removal and normalization, 0 / π modulation and phase detector in sequence to obtain a first angle; the first angle is the angle between the second single pulse and the antenna when the second single pulse signal enters the antenna of the receiving end.

[0014] Preferably, the method further includes: repeating the above steps in sequence to obtain the N-1th angle at which the Nth single pulse signal is incident on the antenna of the receiving end when the antenna of the receiving end receives the Nth single pulse signal.

[0015] Preferably, it also includes:

[0016] When the signal-to-noise ratio of the first signal exceeds a first preset threshold, the first signal is used to participate in correcting the random phase shift;

[0017] When the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

[0018] Preferably, the signal-to-noise ratio of the first signal is obtained by the similarity between the second single pulse signal and the second reference sequence of the receiving end.

[0019] Preferably, it also includes:

[0020] The N-1th angle is smoothed so that the N-1th angle does not jitter with noise.

[0021] Preferably, the first reference sequence and the second reference sequence are: training sequences and / or pilot sequences.

[0022] In the second aspect, a device for anti-interference of angle tracking and measurement of a frequency hopping system of a UAV is also provided, comprising:

[0023] Sum and difference network system: used to process the received single pulse signal to form the Nth sum signal and the Nth difference signal;

[0024] Down-conversion system: used to down-convert, filter, and analog-to-digital convert the received Nth sum signal and Nth difference signal respectively;

[0025] Correlation operation module: used for performing correlation operation on the Nth reference sequence of the receiving end and the Nth single pulse signal to obtain the Nth phase shift generated by the Nth single pulse signal at the receiving end;

[0026] A sum and difference channel mixing module: used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal;

[0027] Correction module: used for taking the difference between the N-1th phase shift and the Nth phase shift as a correction value, for correcting the random phase shift of the first signal after the Nth sum signal and the Nth difference signal are mixed, so as to obtain the Nth mixed signal;

[0028] Phase detection module: used to filter out the out-of-band noise, remove DC and normalize, 0 / π modulate the Nth mixed signal in sequence, and obtain the N-1th angle through the phase detector; the N-1th angle is the angle between the Nth single pulse and the direction of the antenna when the Nth single pulse signal is incident on the antenna of the receiving end.

[0029] Preferably, it also includes:

[0030] Loop module: used to repeatedly execute the above systems and modules in sequence to obtain the N-1th angle when the receiving end antenna receives the Nth single pulse signal and the Nth single pulse signal enters the receiving end antenna.

[0031] Preferably, it also includes:

[0032] A signal-to-noise ratio module: when the signal-to-noise ratio of the first signal exceeds a first preset threshold, the first signal is used to participate in correcting the random phase shift; when the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

[0033] Preferably, it also includes:

[0034] Smoothing module: used for smoothing the N-1th angle so that the N-1th angle does not jitter with noise.

[0035] In summary, the present application includes at least one of the following beneficial technical effects:

[0036] 1. Solved the technical problem of how to measure the angle between the incident single pulse signal and the receiving antenna in the frequency hopping signal state;

[0037] 2. Solved the technical problem that the gain of different frequency hopping points is different. Since the wireless channel is a frequency selective channel, the gain at some frequency points is too low, resulting in poor signal-to-noise ratio and inaccurate measurement angle;

[0038] 3. The technical problem of the measured angle jittering with noise has been solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The invention is a first embodiment of an anti-interference method for angle tracking and measurement of a frequency hopping system of a UAV;

[0040] Figure 2 A second embodiment of the anti-interference method for angle tracking measurement of a frequency hopping system of a UAV;

[0041] Figure 3 A third embodiment of an anti-interference method for angle tracking and measurement of a frequency hopping system of a UAV;

[0042] Figure 4 A fourth embodiment of an anti-interference method for angle tracking measurement of a frequency hopping system of a UAV;

[0043] Figure 5 It is an anti-interference device for angle tracking and measurement of UAV frequency hopping system.

[0044] Description of reference numerals:

[0045] 1. Sum and difference network system; 2. Down-conversion system;

[0046] 3. Correlation operation module; 4. Sum and difference channel mixing module;

[0047] 5. Correction module; 6. Phase detection module;

[0048] 7. Cycle module; 8. Signal-to-noise ratio module;

[0049] 9. Smoothing module. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-5 It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] Frequency-hopping (Frequency-Hopping Spread Spectrum; FHSS) refers to a method of using a pseudo-random code sequence to perform frequency shift keying to make the carrier frequency continuously jump and thus spread the spectrum.

[0052] Usually, single pulse angle measurement is aimed at echo signals of fixed frequency. However, frequency hopping technology is now widely used, so it is necessary to provide a method and device for measuring angles in the presence of frequency hopping signals. According to the method of extracting the angle information of the target from the echo signal, single pulse angle measurement is divided into two types: amplitude comparison method and phase comparison method. The amplitude comparison method is usually used for angle measurement. The focus of the present invention is not here, so the amplitude comparison method or the phase comparison method will not be further elaborated here.

[0053] A method for anti-interference of angle tracking measurement of a frequency hopping system of a UAV, comprising the following steps:

[0054] like Figure 1 As shown, in a first aspect, a method for measuring angles for a frequency hopping signal is provided, comprising:

[0055] S101: using the sum-difference network system of the receiving end to obtain the first sum signal and the first difference signal of the first single pulse signal; the so-called sum-difference network is that the single pulse signals received simultaneously by at least two antennas of the receiving end are subjected to sum operations and difference operations. In this embodiment, the first single pulse signal is subjected to sum and difference operations to obtain the first sum signal and the first difference signal.

[0056] S102: Utilize the sum-difference network system of the receiving end to obtain the second sum signal and the second difference signal of the second single pulse signal; the frequencies of the first single pulse signal and the second single pulse signal are different; since the frequencies of the first single pulse and the second single pulse are different, it is reflected that the transmitting end of the signal sends a frequency hopping signal. Since it is a frequency hopping signal, the transmitting end sends at least two frequency signals. In this embodiment, only two frequency signals are described; if there are more than two frequency signals, this technical solution is still applicable.

[0057] S103: Correlation operation is performed on the first reference sequence of the receiving end and the first sum signal to obtain the first phase shift generated by the first single pulse signal at the receiving end; the correlation operation is used to obtain the correlation and difference between the two signals. Because the first sum signal and the first difference signal must pass through the low noise amplifier 201 (LNA), the local oscillator unit 202, the low-pass filter and amplifier 203 and the analog-to-digital converter 204 before mixing. When passing through the local oscillator unit, a random initial phase will be introduced; this initial phase will affect the accuracy of subsequent angle measurement, so it is necessary to process the initial phase to eliminate the influence on the angle measurement accuracy. The first phase shift can be obtained by using the correlation operation.

[0058] S104: Perform correlation operation on the second reference sequence at the receiving end and the second sum signal to obtain the second phase shift generated by the second single pulse signal at the receiving end; the frequency of the second single pulse signal is different from the frequency of the first single pulse signal, the frequency of the local oscillator unit processing the second single pulse signal is also different, and the introduced random initial phase is also different, that is, the second phase shift, resulting in the second phase shift being unrelated to the first phase shift.

[0059] S105: Using the difference between the first phase shift and the second phase shift as a correction value to correct the random phase shift of the first signal after the second sum signal and the second difference signal are mixed to obtain a first mixed signal; this can overcome different phase errors caused by different frequencies.

[0060] S106: The first mixed signal is subjected to envelope detection to filter out out-of-band noise, DC removal and normalization, 0 / π modulation and phase detector in sequence to obtain a first angle; the first angle is the angle between the second single pulse and the direction of the antenna when the second single pulse signal is incident on the antenna of the receiving end. Before mixing, the second difference signal is also subjected to 0 / π modulation before being mixed with the second sum signal. So far, through the above steps, the angle between the beam formed by the frequency hopping signal and the receiving antenna can be obtained. In this technical solution, the receiving antenna is set on the drone, and the drone is in motion. Therefore, the receiving antenna changes its angle at any time, so the angle between the beam formed by the frequency hopping signal and the receiving antenna also changes at any time.

[0061] like Figure 2 As shown, preferably, it also includes: S107: repeating the above steps in sequence to obtain the N-1th angle when the Nth single pulse signal is incident on the antenna of the receiving end when the antenna of the receiving end receives the Nth single pulse signal. Repeating the above steps can realize the method of single pulse angle measurement under multiple frequencies, that is, frequency hopping state. As mentioned above, the reason why N single pulse signals are formed and incident on the N-1th angle of the receiving antenna is because the receiving antenna is moving or changing its angle at any time.

[0062] like Figure 3 As shown, preferably, it also includes: S108: when the signal-to-noise ratio of the first signal exceeds the first preset threshold, the first signal is used to participate in correcting the random phase shift; the first preset threshold is set to prevent the first signal below the first preset threshold from entering the subsequent signal processing link, and the first signal below the first preset value signal-to-noise ratio may be noise. The signal-to-noise ratio is the ratio of the signal to the noise, referred to as SNR.

[0063] When the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

[0064] Preferably, the signal-to-noise ratio of the first signal is obtained by the similarity between the second single pulse signal and the second reference sequence of the receiving end.

[0065] like Figure 4 As shown, preferably, it also includes:

[0066] S109: Smoothing the N-1th angle so that the N-1th angle does not jitter with noise. The smoothing process is low-pass filtering. For example: low-pass filtering is performed on the N-1th angle measurement value, and the angle measurement value a(n) at time n is assumed to be valid. Then the filtered angle measurement value b(n)=1 / 8*a(n)+7 / 8*b(n-1) is output at time n. The current angle measurement ratio only accounts for 1 / 8, and the angle value measured previously accounts for 7 / 8. Through such effective smoothing, the measured angle will not jitter with noise, and can be tracked in real time. The time to measure an angle is 1ms, and smoothing 8 times is less than 8ms. The angle change of such a short time signal is generally less than 1°, so it can be kept up with in real time.

[0067] Preferably, the first reference sequence and the second reference sequence are: a training sequence and / or a pilot sequence. The functions of the pilot sequence and the training sequence are to obtain accurate symbol synchronization and frequency offset correction. Usually, one sequence is sufficient, or both sequences can be used together for frequency offset correction.

[0068] An anti-interference device for angle tracking and measurement of a frequency hopping system of an unmanned aerial vehicle, comprising the following:

[0069] Second, as Figure 5 As shown, an angle measuring device for a frequency hopping signal is also provided, comprising:

[0070] Sum-difference network system 1: used to process the received single pulse signal to form the Nth sum signal and the Nth difference signal; N is a positive integer, indicating the nth single pulse or the nth frequency of the single pulse.

[0071] Down-conversion system 2: used to down-convert, filter, and convert the received Nth sum signal and Nth difference signal respectively; the down-conversion system is a prior art and will not be elaborated on in detail. However, it should be pointed out that if there are N sum signals or N difference signals, it means that there are N local oscillator units 201 for down-conversion. Correspondingly, there are also N filters 202 and analog-to-digital converters 203, or the filters and analog-to-digital converters have N settings.

[0072] Correlation operation module 3: used for performing correlation operation on the Nth reference sequence of the receiving end and the Nth sum signal to obtain the Nth phase shift generated by the Nth single pulse signal at the receiving end;

[0073] Sum and difference channel mixing module 4: used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal;

[0074] Correction module 5: used for taking the difference between the N-1th phase shift and the Nth phase shift as a correction value, for correcting the random phase shift of the first signal after the Nth sum signal and the Nth difference signal are mixed, so as to obtain the Nth mixed signal;

[0075] Phase detector module 6: used to subject the Nth mixed signal to envelope detection, filtering out-of-band noise, DC removal and normalization, 0 / π modulation in sequence, and obtain the N-1th angle through a phase detector; the N-1th angle is the angle between the Nth single pulse and the direction of the antenna when the Nth single pulse signal is incident on the antenna of the receiving end.

[0076] Preferably, Figure 5 As shown, it also includes:

[0077] Loop module 7: used to repeatedly execute the above systems and modules in sequence to obtain the N-1th angle when the receiving end antenna receives the Nth single pulse signal and the Nth single pulse signal enters the receiving end antenna.

[0078] Preferably, Figure 5 As shown, it also includes:

[0079] The signal-to-noise ratio module 8 is used to: when the signal-to-noise ratio of the first signal exceeds a first preset threshold, the first signal is used to participate in correcting the random phase shift; when the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

[0080] Preferably, Figure 5 As shown, it also includes:

[0081] Smoothing module 9: used for smoothing the N-1th angle so that the N-1th angle does not jitter with noise.

[0082] In summary, the present application includes at least one of the following beneficial technical effects:

[0083] 1. Solved the technical problem of how to measure the angle between the incident single pulse signal and the receiving antenna in the frequency hopping signal state;

[0084] 2. Solved the technical problem that the gain of different frequency hopping points is different. Since the wireless channel is a frequency selective channel, the gain at some frequency points is too low, resulting in poor signal-to-noise ratio and inaccurate measurement angle;

[0085] 3. The technical problem of the measured angle jittering with noise has been solved.

[0086] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0087] The above are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any feature disclosed in this specification (including the abstract and drawings), unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

Claims

1. A method for anti-interference of angle tracking measurement of UAV frequency hopping system, characterized in that: include: Acquire a first sum signal and a first difference signal of the first single pulse signal by using a sum-difference network system at a receiving end; A second sum signal and a second difference signal of a second single pulse signal are obtained by using a sum-difference network system at a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different; Performing a correlation operation on a first reference sequence at a receiving end and a first sum signal to obtain a first phase shift generated by the first single pulse signal at the receiving end; Performing correlation operation on the second reference sequence at the receiving end and the second sum signal to obtain a second phase shift generated by the second single pulse signal at the receiving end; Using the difference between the first phase shift and the second phase shift as a correction value to correct the random phase shift of the first signal after the second sum signal and the second difference signal are mixed, so as to obtain a first mixed signal; The first mixed signal is subjected to envelope detection to filter out-of-band noise, DC removal and normalization, 0 / π modulation and phase detector in sequence to obtain a first angle; the first angle is the angle between the second single pulse and the antenna when the second single pulse signal enters the antenna of the receiving end.

2. The method according to claim 1, characterized in that: Also includes: The above steps are repeated in sequence to obtain the N-1th angle at which the Nth single pulse signal enters the antenna of the receiving end when the antenna of the receiving end receives the Nth single pulse signal.

3. The method according to claim 1, characterized in that: Also includes: When the signal-to-noise ratio of the first signal exceeds a first preset threshold, the first signal is used to participate in correcting the random phase shift; When the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

4. The method according to claim 3, characterized in that The signal-to-noise ratio of the first signal is obtained through the similarity between the second single pulse signal and the second reference sequence of the receiving end.

5. The method according to claim 2, characterized in that: Also includes: The N-1th angle is smoothed so that the N-1th angle does not jitter with noise.

6. The method according to claim 1 or 4, characterized in that: The first reference sequence and the second reference sequence are: a training sequence and / or a pilot sequence.

7. An anti-interference device for angle tracking and measurement of UAV frequency hopping system, characterized in that: include: Sum and difference network system: used to process the received single pulse signal to form the Nth sum signal and the Nth difference signal; Down-conversion system: used to down-convert, filter, and analog-to-digital convert the received Nth sum signal and Nth difference signal respectively; Correlation operation module: used for performing correlation operation on the Nth reference sequence of the receiving end and the Nth single pulse signal to obtain the Nth phase shift generated by the Nth single pulse signal at the receiving end; A sum and difference channel mixing module: used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal; Correction module: used for taking the difference between the N-1th phase shift and the Nth phase shift as a correction value, for correcting the random phase shift of the first signal after the Nth sum signal and the Nth difference signal are mixed, so as to obtain the Nth mixed signal; Phase detection module: used to filter out the out-of-band noise, remove DC and normalize, 0 / π modulate the Nth mixed signal in sequence, and obtain the N-1th angle through the phase detector; the N-1th angle is the angle between the Nth single pulse and the direction of the antenna when the Nth single pulse signal is incident on the antenna of the receiving end.

8. The device according to claim 7, characterized in that Also includes: Loop module: used to repeatedly execute the above systems and modules in sequence to obtain the N-1th angle when the receiving end antenna receives the Nth single pulse signal and the Nth single pulse signal enters the receiving end antenna.

9. The device according to claim 7, characterized in that Also includes: A signal-to-noise ratio module: used for, when the signal-to-noise ratio of the first signal exceeds a first preset threshold, using the first signal to participate in correcting the random phase shift; When the signal-to-noise ratio of the first signal is lower than the first preset threshold, the first signal is not used to participate in correcting the random phase shift.

10. The device according to claim 8, characterized in that Also includes: Smoothing module: used for smoothing the N-1th angle so that the N-1th angle does not jitter with noise.

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