CN115390063A - Anti-interference method and device for angle tracking measurement of unmanned aerial vehicle frequency hopping system - Google Patents

Abstract

The application relates to an anti-interference method and device for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle, and relates to the field of signal processing. It includes: acquiring a first sum signal and a first difference signal of a first monopulse signal by using a sum-difference network system of a receiving end; acquiring a second sum signal and a second difference signal of a second monopulse signal by using a sum-difference network system of a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different; performing correlation operation on a first reference sequence and a first sum signal of a receiving end to obtain a first phase shift generated by a first monopulse signal at the receiving end; performing correlation operation on the second reference sequence of the receiving end and the second sum signal to obtain a second phase shift generated by the second monopulse signal at the receiving end; and taking the difference value of the first phase shift and the second phase shift as a correction value for correcting the random phase shift of the first signal after the second sum signal and the second difference signal are mixed. The method has the technical effect of measuring the angle of the frequency hopping signal.

Description

Anti-interference method and device for angle tracking measurement of unmanned aerial vehicle frequency hopping system

Technical Field

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

Background

Currently, monopulse angle measurement is a commonly used angle measurement method in radar, which uses multiple antennas to receive echo signals simultaneously, and obtains angle position information of a target by comparing amplitudes or phases of the echo signals. The monopulse angle measurement method can determine the angle error information of the target only by one echo pulse, is simple to operate, has strong real-time performance and high angle measurement precision, and therefore, is widely applied to modern phased array radar systems and has important application value in the fields of radar, sonar, wireless communication and the like.

The mobile communication channel environment is severe, and various interferences are not good. In order to resist the interference of some frequencies, the frequency hopping technology is one of the effective methods; how to measure the angle of the frequency hopping signal is a technical problem to be solved urgently.

In view of the above-mentioned related art, the inventors found that at least the following problems exist in the related art: how to measure the angle by using a single pulse in a frequency hopping state; because each frequency jitter introduces a random initial phase, the angle measurement precision is not enough; the angle jitter with noise is measured.

Disclosure of Invention

In order to solve the technical problem, the application provides an anti-interference method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle and an anti-interference device for angle tracking measurement of the frequency hopping system of the unmanned aerial vehicle.

The application provides an anti-interference method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle, which adopts the following technical scheme:

in a first aspect, an anti-interference method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle is provided, which includes:

acquiring a first sum signal and a first difference signal of the first monopulse signal by using a sum-difference network system of a receiving end;

acquiring a second sum signal and a second difference signal of the second monopulse signal by using a sum-difference network system of a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different;

performing correlation operation on a first reference sequence and a first sum signal of a receiving end to obtain a first phase shift generated by a first monopulse signal at the receiving end;

performing correlation operation on a second reference sequence of the receiving end and a second sum signal to obtain a second phase shift generated by a second monopulse signal at the receiving end;

taking the difference value of the first phase shift and the second phase shift as a correction value for correcting 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;

sequentially carrying out envelope detection on the first mixed signal to filter out-of-band noise, removing direct current and normalization, carrying out 0/pi modulation and carrying out a phase discriminator to obtain a first angle; the first angle is an angle pointed by the second single pulse and the antenna when the second single pulse signal is incident to the antenna of the receiving end.

Preferably, the method further comprises the following steps: and repeating the steps in sequence to obtain the N-1 angle when the antenna of the receiving end receives the Nth monopulse signal and the Nth monopulse signal enters the antenna of the receiving end.

Preferably, the method further comprises the following steps:

the first signal is used for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold;

the first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

Preferably, the signal-to-noise ratio of the first signal is obtained through the similarity between the second monopulse signal and the second reference sequence at the receiving end.

Preferably, the method further comprises the following steps:

and smoothing the N-1 st angle to ensure that the N-1 st angle does not shake along with noise.

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

In a second aspect, an anti-interference device for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle is provided, which includes:

sum and difference network system: the signal processing device is used for processing the received single pulse signal to form an Nth sum signal and an Nth difference signal;

a down-conversion system: the down-conversion module is used for respectively performing down-conversion, filtering and analog-to-digital conversion on the received Nth sum signal and the received Nth difference signal;

a correlation operation module: the N-th reference sequence of the receiving end and the N-th single pulse signal are subjected to correlation operation to obtain an N-th phase shift generated by the N-th single pulse signal at the receiving end;

and a difference channel mixing module: the signal processing device is used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal;

a correction module: the difference value of the N-1 phase shift and the Nth phase shift is used 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 that an Nth mixed signal is obtained;

the phase discrimination module: the N mixed signal is used for filtering out-of-band noise through envelope detection in sequence, removing direct current and normalization, carrying out 0/pi modulation, and obtaining an N-1 angle through a phase discriminator; the N-1 angle is an angle pointed by the Nth monopulse and the antenna when the Nth monopulse signal is incident to the antenna of the receiving end.

Preferably, the method further comprises the following steps:

a circulation module: and the system and the modules are sequentially and repeatedly executed to obtain the N-1 angle when the receiving end antenna receives the Nth single pulse signal and the Nth single pulse signal enters the receiving end antenna.

Preferably, the method further comprises the following steps:

a signal-to-noise ratio module: for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold; the first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

Preferably, the method further comprises the following steps:

a smoothing module: the method is used for smoothing the N-1 st angle, so that the N-1 st angle does not shake with noise.

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

1. the technical problem of how to measure the angle between an incident monopulse signal and a receiving antenna in a frequency hopping signal state is solved;

2. the technical problems that different frequency hopping frequency points have different gains, and due to the fact that frequency selective channels are used for wireless channels, gains of some frequency points are too low, signal-to-noise ratios are poor, and measuring angles are inaccurate are solved;

3. the technical problem that the measured angle shakes along with the noise is solved.

Drawings

Fig. 1 is a first embodiment of an anti-jamming method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle;

fig. 2 is a second embodiment of an anti-jamming method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle;

fig. 3 is a third embodiment of an anti-jamming method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle;

fig. 4 is a fourth embodiment of an anti-jamming method for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle;

fig. 5 is an anti-jamming device for angle tracking measurement of a frequency hopping system of an unmanned aerial vehicle.

Description of the reference numerals:

1. a sum and difference network system; 2. a down conversion system;

3. a correlation operation module; 4. a sum-difference channel mixing module;

5. a correction module; 6. a phase discrimination module;

7. a circulation module; 8. a signal-to-noise ratio module;

9. and a smoothing module.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to fig. 1-5 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The Frequency Hopping (FHSS) is a method of spreading a Spectrum by Frequency shift keying using a pseudo random code sequence to continuously hop a carrier Frequency.

Generally, the single-pulse angle measurement is directed to the echo signal with a fixed frequency, but now the frequency hopping technology is widely applied, and it is necessary to provide a method and a device for measuring the angle in the presence of the frequency hopping signal. According to the method for extracting the angle information of the target from the echo signal, the single pulse angle measurement is divided into an amplitude comparison method and a phase comparison method, and the single pulse angle measurement is generally carried out by adopting the amplitude comparison method. The invention is not focused on here and therefore is not further described here with or without angle measurements.

An anti-interference method for angle tracking measurement of an unmanned aerial vehicle frequency hopping system comprises the following steps:

as shown in fig. 1, in a first aspect, there is provided an angle measurement method for a frequency hopping signal, including:

s101: acquiring a first sum signal and a first difference signal of a first monopulse signal by using a sum-difference network system of a receiving end; the sum-difference network is a network in which a sum operation and a difference operation are performed on signals of a single pulse received by at least two antennas at a receiving end at the same time. In this embodiment, the first single pulse signal is subjected to sum and difference operations to obtain a first sum signal and a first difference signal.

S102: acquiring a second sum signal and a second difference signal of the second monopulse signal by using a sum-difference network system of a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different; because the frequencies of the first single pulse and the second single pulse are different, the frequency hopping signal is sent by the sending end which represents the signal. Since the frequency hopping signal is used, the transmitting end transmits signals of at least two frequencies. In the present embodiment, only signals of two frequencies are explained; if the signal has more than two frequencies, the method is still suitable for the technical scheme.

S103: performing correlation operation on a first reference sequence and a first sum signal of a receiving end to obtain a first phase shift generated by a first monopulse signal at the receiving end; the correlation operation is used to obtain the correlation and the difference between the two signals. Since the first sum signal and the first difference signal are passed through a low noise amplifier 201 (LNA), a local oscillator unit 202, a low pass filter and amplifier 203, and an analog-to-digital converter 204 before being mixed. When the signal passes through the local oscillation unit, a random initial phase is introduced; since the initial phase affects the accuracy of subsequent angle measurement, the initial phase needs to be processed to eliminate the effect on the accuracy of angle measurement. The first phase shift may be obtained using a correlation operation.

S104: performing correlation operation on a second reference sequence of the receiving end and a second sum signal to obtain a second phase shift generated by a second monopulse 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 a local oscillation unit for processing the second single pulse signal is also different, and the introduced random initial phase is also different, namely, the second phase shift, so that the generated second phase shift is not related to the first phase shift.

S105: taking the difference value of the first phase shift and the second phase shift as a correction value, and correcting 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 due to different frequencies.

S106: sequentially carrying out envelope detection on the first mixed signal to filter out-of-band noise, removing direct current and normalization, carrying out 0/pi modulation and carrying out a phase discriminator to obtain a first angle; the first angle is an angle pointed by the second single pulse and the antenna when the second single pulse signal enters the antenna of the receiving end. The second difference signal is also subjected to 0/pi modulation before mixing and then mixed with the second sum signal. By the above steps, the angle between the beam formed by the hopping signal and the receiving antenna can be obtained. In this technical scheme, receiving antenna sets up on unmanned aerial vehicle, and unmanned aerial vehicle is in the motion, and consequently, receiving antenna is changing the angle at any time, so, the angle between the wave beam that the frequency hopping signal formed and receiving antenna also is changing at any time.

As shown in fig. 2, it preferably further includes: s107: and repeating the steps in sequence to obtain the N-1 angle when the Nth monopulse signal is incident to the antenna of the receiving end when the antenna of the receiving end receives the Nth monopulse signal. The above steps are repeated, so that the method for measuring the angle of the single pulse under the condition of multiple frequencies, namely under the frequency hopping state, can be realized. As mentioned above, N monopulse signals are formed and incident on the N-1 st angle of the receiving antenna because the receiving antenna is moving or changing angles at any time.

As shown in fig. 3, it preferably further includes: s108: the first signal is used for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold; the first preset threshold is set to prevent the first signal lower than the first preset threshold from entering a subsequent signal processing link, where the first signal lower than the first preset signal-to-noise ratio may be noise. The signal-to-noise ratio is the ratio of signal to noise, referred to as SNR.

The first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

Preferably, the signal-to-noise ratio of the first signal is obtained through the similarity between the second monopulse signal and the second reference sequence at the receiving end.

As shown in fig. 4, it preferably further includes:

s109: and smoothing the N-1 st angle to ensure that the N-1 st angle does not shake along with noise. And performing low-pass filtering processing on the smoothing processing. For example: and (4) performing low-pass filtering on the angle measurement value N-1, and setting the angle measurement value a (N) at the moment N, wherein the angle measurement value a (N) is effective. And outputting a filtered angle measurement value b (n) =1/8*a (n) +7/8*b (n-1) at the moment n, wherein the current angle measurement proportion only accounts for 1/8, and the previously measured angle value accounts for 7/8, so that the measured angle cannot follow noise jitter through effective smoothing, and meanwhile, real-time tracking can be realized. The time for measuring an angle is 1ms, the time for smoothing is less than 8ms even after 8 times, and the angle variation of the signal is generally less than 1 degree in short time, so that the method can be completely kept up to real time.

Preferably, the first reference sequence and the second reference sequence are: training sequences and/or pilot sequences. The pilot sequence and the training sequence are used to obtain accurate symbol synchronization and frequency offset correction. Usually, one sequence is used, or two sequences can be used together as the frequency offset correction.

The utility model provides a to unmanned aerial vehicle frequency hopping system angle tracking measurement anti jamming unit, includes as follows:

in a second aspect, as shown in fig. 5, there is also provided an angle measuring apparatus for a frequency hopping signal, including:

sum and difference network system 1: the signal processing device is used for processing the received single pulse signal to form an Nth sum signal and an Nth difference signal; n is a positive integer and represents the second single pulse or the single pulse at the second frequency.

Down-conversion system 2: the down-conversion module is used for respectively performing down-conversion, filtering and analog-to-digital conversion on the received Nth sum signal and the received Nth difference signal; down conversion systems are prior art and not described in great detail. However, it should be noted that if there are N sum signals or N difference signals, it means that there are N local oscillation units 201 for down-conversion. Accordingly, the filter 202 and the analog-to-digital converter 203 also have N, or the filter and the analog-to-digital converter have N settings.

Correlation operation module 3: the device is used for carrying out correlation operation on the Nth reference sequence and the Nth sum signal of the receiving end to obtain the Nth phase shift generated by the Nth monopulse signal at the receiving end;

and the difference channel mixing module 4: the signal processing device is used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal;

and the correction module 5: the difference value of the N-1 phase shift and the Nth phase shift is used 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 that an Nth mixed signal is obtained;

the phase discrimination module 6: the N mixed signal is used for filtering out-of-band noise through envelope detection in sequence, removing direct current and normalization, carrying out 0/pi modulation, and obtaining an N-1 angle through a phase discriminator; the N-1 angle is an angle pointed by the Nth monopulse and the antenna when the Nth monopulse signal is incident to the antenna of the receiving end.

Preferably, as shown in fig. 5, the method further includes:

the circulation module 7: and the system and the modules are sequentially and repeatedly executed to obtain the N-1 angle when the receiving end antenna receives the Nth single pulse signal and the Nth single pulse signal enters the receiving end antenna.

Preferably, as shown in fig. 5, the method further includes:

the signal-to-noise ratio module 8: for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold; the first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

Preferably, as shown in fig. 5, the method further includes:

the smoothing module 9: the method is used for smoothing the N-1 st angle, so that the N-1 st angle does not shake with noise.

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

1. the technical problem of how to measure the angle between an incident monopulse signal and a receiving antenna in a frequency hopping signal state is solved;

2. the technical problems that different frequency hopping frequency points have different gains, and due to the fact that frequency selective channels are used for wireless channels, gains of some frequency points are too low, signal-to-noise ratios are poor, and measuring angles are inaccurate are solved;

3. the technical problem that the measured angle shakes along with the noise is solved.

Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuitry, field Programmable Gate Arrays (FPGAs), application Specific Integrated Circuits (ASICs), application Specific Standard Products (ASSPs), system on a chip (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, receiving data and instructions from, and transmitting data and instructions to, a storage system, at least one input device, and at least one output device.

The foregoing is a preferred embodiment of the present application and is not intended to limit the scope of the present application in any way, and any features disclosed in this specification (including the abstract and drawings) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.

Claims (10)

1. The utility model provides a to unmanned aerial vehicle frequency hopping system angle tracking measurement anti-jamming method which characterized in that includes:

acquiring a first sum signal and a first difference signal of a first monopulse signal by using a sum-difference network system of a receiving end;

acquiring a second sum signal and a second difference signal of a second monopulse signal by using a sum-difference network system of a receiving end; the frequencies of the first single pulse signal and the second single pulse signal are different;

performing correlation operation on a first reference sequence and a first sum signal of a receiving end to obtain a first phase shift generated by a first monopulse signal at the receiving end;

performing correlation operation on a second reference sequence of the receiving end and a second sum signal to obtain a second phase shift generated by a second monopulse signal at the receiving end;

taking the difference value of the first phase shift and the second phase shift as a correction value, and correcting 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;

sequentially carrying out envelope detection on the first mixed signal to filter out-of-band noise, removing direct current and normalization, carrying out 0/pi modulation and carrying out a phase discriminator to obtain a first angle; the first angle is an angle pointed by the second single pulse and the antenna when the second single pulse signal is incident to the antenna of the receiving end.

2. The method of claim 1, further comprising: and repeating the steps in sequence to obtain the N-1 angle when the Nth monopulse signal is incident to the antenna of the receiving end when the antenna of the receiving end receives the Nth monopulse signal.

3. The method of claim 1, further comprising:

the first signal is used for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold;

the first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

4. The method of claim 3, wherein the signal-to-noise ratio of the first signal is obtained by similarity between the second monopulse signal and a second reference sequence at a receiving end.

5. The method of claim 2, further comprising:

and smoothing the N-1 st angle so that the N-1 st angle does not shake along with noise.

6. The method of claim 1 or 4, wherein the first and second reference sequences are: training sequences and/or pilot sequences.

7. The utility model provides a measure anti jamming unit to unmanned aerial vehicle frequency hopping system angle tracking which characterized in that includes:

a sum and difference network system: the signal processing device is used for processing the received single pulse signal to form an Nth sum signal and an Nth difference signal;

a down-conversion system: the down-conversion module is used for respectively performing down-conversion, filtering and analog-to-digital conversion on the received Nth sum signal and the received Nth difference signal;

a correlation operation module: the device is used for carrying out 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;

and a difference channel mixing module: the signal processing device is used for mixing the Nth sum signal and the Nth difference signal to obtain a first signal;

a correction module: the difference value of the N-1 phase shift and the Nth phase shift is used 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 that an Nth mixed signal is obtained;

the phase discrimination module: the N mixed signal is used for filtering out-of-band noise through envelope detection in sequence, removing direct current and normalization, carrying out 0/pi modulation, and obtaining an N-1 angle through a phase discriminator; the N-1 angle is an angle pointed by the Nth monopulse and the antenna when the Nth monopulse signal enters the antenna of the receiving end.

8. The apparatus of claim 7, further comprising:

a circulation module: and the system and the modules are sequentially and repeatedly executed to obtain the N-1 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 apparatus of claim 7, further comprising:

a signal-to-noise ratio module: for participating in correcting the random phase shift when the signal-to-noise ratio of the first signal exceeds a first preset threshold; the first signal is not used to participate in correcting the random phase shift when the signal-to-noise ratio of the first signal is below the first preset threshold.

10. The apparatus of claim 8, further comprising:

a smoothing module: the method is used for smoothing the N-1 st angle so that the N-1 st angle does not shake along with noise.

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