Sweep frequency interference suppression method and device for remote control signal of unmanned aerial vehicle

Abstract

The invention discloses an unmanned aerial vehicle remote control signal-oriented sweep interference suppression method, which relates to the technical field of communication, and realizes interference signal reconstruction in a digital domain based on sweep interference frequency change estimation of an instantaneous frequency estimation algorithm and in combination with estimated instantaneous power information so as to achieve an interference signal suppression function. Therefore, interference is effectively reduced while useful signals are received. The invention also discloses a sweep interference suppression device for the remote control signal of the unmanned aerial vehicle, the normalized least mean square algorithm (NLMS) is selected, the method is more suitable for interference suppression in a low signal-to-noise ratio scene, error accumulation can be effectively reduced, and the filtering precision is improved. Through the improvement, the anti-interference capability of the system is remarkably improved, so that remote control signals of the unmanned aerial vehicle can still be normally received under the condition of relatively strong interference.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a method and device for suppressing frequency sweep interference of unmanned aerial vehicle remote control signals. Background Art

[0002] Interference suppression technology is crucial in fields such as military communications and drone control. With the development of electronic warfare technology, swept frequency interference has become a complex and difficult-to-suppress interference method. Sweep frequency interference interferes with communication signals by continuously changing the frequency within the spectrum range, which has a significant impact on drone control systems that use frequency hopping, and may cause signal loss or false detection. Existing static filter methods are difficult to effectively deal with such interference due to their lack of adaptability to dynamic frequency changes; traditional adaptive filtering technologies such as the least mean square (LMS) algorithm have limited performance in low signal-to-noise ratio environments and cannot provide high-precision interference suppression effects.

[0003] To solve these problems, instantaneous frequency estimation technology has gradually attracted attention. It can track the interference frequency changes in real time and provide dynamic reference for adaptive filters. However, the current instantaneous frequency estimation and suppression methods have limited effects under the coexistence of multiple interferences. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method and device for suppressing frequency-sweep interference for UAV remote control signals. In the presence of frequency-hopping UAV remote control signals, the instantaneous frequency of the frequency-sweep interference signal is estimated by a digital method, and the interference signal is suppressed by an adaptive filter, thereby effectively reducing interference while receiving the signal. The present invention greatly suppresses the interference in the target signal received by the UAV, and provides a powerful platform support and digital calculation method for communication equipment to improve the robustness and signal reception accuracy of the wireless communication system in self-interference suppression and electronic attack scenarios.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] In a first aspect, a method for suppressing frequency sweep interference of a remote control signal of an unmanned aerial vehicle is provided according to the present invention, comprising:

[0007] Estimate the instantaneous frequency of the chirp over the entire bandwidth of the drone remote controller signal;

[0008] reconstructing the interference signal in the digital domain based on the estimated instantaneous power;

[0009] The interference signal is subtracted from the drone remote controller signal through adaptive filtering.

[0010] As a further optimization scheme of the frequency sweep interference suppression method for UAV remote control signals described in the present invention, the estimated instantaneous frequency for:

[0011]

[0012] in, is the phase value of the interference signal at time n, is the phase value of the interference signal at time n-1, x(n) is the value of the interference signal at time n, and x * (n-1) is the conjugate of the value of the interference signal at time n-1, is the instantaneous frequency estimated by the single difference operation.

[0013] As a further optimization scheme of the frequency sweep interference suppression method for the remote control signal of the unmanned aerial vehicle described in the present invention, a weighted phase difference estimator is used to estimate the instantaneous frequency, and a smoothing filter and time averaging method are used to reduce the variance of the interference signal. For a stationary signal with a signal-to-noise ratio sufficient to reach the Cramer-Rao bound, the weighted phase difference estimator is given as:

[0014]

[0015] in, is the instantaneous frequency estimated by the weighted phase difference estimator, h n is the nth smoothing window, N The total size of the window.

[0016] As a further optimization scheme of the method for suppressing frequency sweep interference of UAV remote control signals described in the present invention,

[0017]

[0018] As a further optimization scheme of the frequency sweep interference suppression method for the remote control signal of the unmanned aerial vehicle described in the present invention, the interference signals x(t), x(t) are reconstructed as follows:

[0019]

[0020] Where A(t) is the instantaneous amplitude of the interference signal, w 0 is a parameter related to the center frequency, φ 0 is the initial phase, ψ is the sweep rate, t is the time, j is the imaginary unit, w 0 It is used for local reconstruction To assign a value.

[0021] As a further optimization scheme of the swept frequency interference suppression method for UAV remote control signals described in the present invention, for large signal-to-noise ratio scenarios, the normalized minimum mean square error method is used to update the filter taps of the adaptive filtering to achieve the adaptive function.

[0022] In a second aspect, a frequency sweep interference suppression device for a UAV remote control signal includes an estimation module, a reconstruction module and an interference suppression module; wherein:

[0023] An estimation module for estimating the instantaneous frequency of the linear frequency modulation over the entire bandwidth of the drone remote controller signal;

[0024] A reconstruction module, configured to reconstruct the interference signal in a digital domain according to the estimated instantaneous power;

[0025] Interference suppression module, used to subtract interference signals from the drone remote controller signal through adaptive filtering.

[0026] As a further optimization scheme of the swept frequency interference suppression device for UAV remote control signals described in the present invention, an FIR filter is used to implement adaptive filtering, and the adaptive filtering uses a normalized least mean square algorithm NLMS to dynamically adjust the FIR filter parameters.

[0027] In a third aspect, an embodiment of the present invention further provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein when the processor executes the computer program, the steps of the method for suppressing swept frequency interference for unmanned aerial vehicle remote control signals as described in the first aspect above or any corresponding embodiment thereof are implemented.

[0028] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for suppressing swept frequency interference for unmanned aerial vehicle remote control signals as described in the first aspect or any corresponding embodiment thereof are implemented.

[0029] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0030] (1) The frequency sweeping interference suppression method proposed in the present invention is based on adaptive filtering technology. Compared with the static interference suppression method in the prior art, it can effectively deal with non-fixed narrowband interference, especially frequency sweeping interference (such as linear frequency modulation signal). The existing interference suppression technology is mainly aimed at interference signals with constant frequency or fixed bandwidth. However, the present invention can adapt to the interference signal characteristics of frequency hopping by estimating the instantaneous frequency of the interference signal in real time, which significantly improves the accuracy and robustness of interference suppression.

[0031] (2) The instantaneous frequency estimation method used in the present invention accurately captures the frequency change of the swept frequency signal, realizes real-time reconstruction of the interference signal through the formula, and performs filtering processing of the interference signal through adaptive filtering technology. Compared with the traditional fixed frequency filter, this dynamic frequency tracking method has stronger adaptability, especially in complex application scenarios such as frequency hopping of drone remote control system, and can maintain the stability of interference suppression and signal detection at the same time.

[0032] (3) Compared with the widely used least mean square algorithm (LMS), the present invention selects the normalized least mean square algorithm (NLMS), which is more suitable for interference suppression in low signal-to-noise ratio scenarios, and can effectively reduce the accumulation of errors and improve the accuracy of filtering. This improvement significantly enhances the anti-interference ability of the system, so that the UAV remote control signal can still be received normally in the presence of strong interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of adaptive filtering to suppress interference signals after estimating the instantaneous frequency of the interference signal.

[0034] Figure 2 Schematic diagram of the verification platform method. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The present invention proposes a method for suppressing frequency sweep interference of a remote control signal of an unmanned aerial vehicle, comprising:

[0037] Estimate the instantaneous frequency of the chirp over the entire bandwidth of the drone remote controller signal;

[0038] reconstructing the interference signal in the digital domain based on the estimated instantaneous power;

[0039] The interference signal is subtracted from the drone remote controller signal through adaptive filtering.

[0040] As a further optimization scheme of the frequency sweep interference suppression method for UAV remote control signals described in the present invention, the estimated instantaneous frequency for:

[0041]

[0042] in, is the phase value of the interference signal at time n, is the phase value of the interference signal at time n-1, x(n) is the value of the interference signal at time n, and x *(n-1) is the conjugate of the value of the interference signal at time n-1, is the instantaneous frequency estimated by the single difference operation.

[0043] As a further optimization scheme of the frequency sweep interference suppression method for the remote control signal of the unmanned aerial vehicle described in the present invention, a weighted phase difference estimator is used to estimate the instantaneous frequency, and a smoothing filter and time averaging method are used to reduce the variance of the interference signal. For a stationary signal with a signal-to-noise ratio sufficient to reach the Cramer-Rao bound, the weighted phase difference estimator is given as:

[0044]

[0045] in, is the instantaneous frequency estimated by the weighted phase difference estimator, h n is the nth smoothing window, N The total size of the window.

[0046] As a further optimization scheme of the method for suppressing frequency sweep interference of UAV remote control signals described in the present invention,

[0047]

[0048] As a further optimization scheme of the frequency sweep interference suppression method for the remote control signal of the unmanned aerial vehicle described in the present invention, the interference signals x(t), x(t) are reconstructed as follows:

[0049]

[0050] Where A(t) is the instantaneous amplitude of the interference signal, w 0 is a parameter related to the center frequency, φ 0 is the initial phase, ψ is the sweep rate, t is the time, j is the imaginary unit, w 0 It is used for local reconstruction To assign a value.

[0051] As a further optimization scheme of the swept frequency interference suppression method for UAV remote control signals described in the present invention, for large signal-to-noise ratio scenarios, the normalized minimum mean square error method is used to update the filter taps of the adaptive filtering to achieve the adaptive function. Figure 1 Schematic diagram of adaptive filtering to suppress interference signals after estimating the instantaneous frequency of the interference signal.

[0052] A frequency sweep interference suppression device for unmanned aerial vehicle remote control signals comprises an estimation module, a reconstruction module and an interference suppression module; wherein:

[0053] An estimation module for estimating the instantaneous frequency of the linear frequency modulation over the entire bandwidth of the drone remote controller signal;

[0054] A reconstruction module, configured to reconstruct the interference signal in a digital domain according to the estimated instantaneous power;

[0055] Interference suppression module, used to subtract interference signals from the drone remote controller signal through adaptive filtering.

[0056] As a further optimization scheme of the swept frequency interference suppression device for UAV remote control signals described in the present invention, an FIR filter is used to implement adaptive filtering, and the adaptive filtering uses a normalized least mean square algorithm NLMS to dynamically adjust the FIR filter parameters.

[0057] First, the instantaneous frequency (IFS) of the linear frequency modulation over its entire bandwidth is estimated, and then the interference signal is reconstructed in the digital domain based on the estimated instantaneous power, and then the interference signal is subtracted from the received signal through adaptive filtering. In this way, the interference signal is suppressed.

[0058] (1) First, the target signal is collected through the RF front end, which mainly includes down-conversion, low-pass amplification, and digital-to-analog (AD) conversion to collect the discrete digital signal of the target wireless signal.

[0059] (2) After AD conversion, configure the interference instantaneous frequency estimator. The weighted phase difference estimator is given by

[0060]

[0061] where h n , that is, the smoothing window, is determined by the following formula:

[0062]

[0063] Where N is the total window size.

[0064] (3) Based on the interference signal frequency estimation, the interference signal amplitude and phase estimation are realized to achieve local interference signal x(t) reconstruction.

[0065]

[0066] Where A(t) is the instantaneous amplitude of the interference signal, w 0 Related to the center frequency, φ 0 is the initial phase, and is the sweep rate.

[0067] (4) Adaptive filtering configuration: By inputting the acquired signal and the locally reconstructed interference signal, the normalized least mean square algorithm (NLMS) is used to dynamically adjust the FIR filter parameters in order to dynamically adjust the local reconstructed signal to completely offset the interference signal term in the acquired signal, thereby ensuring the matching degree of the interference signal term and outputting the final real signal term to achieve interference signal suppression.

[0068] (5) In order to verify the feasibility of simultaneous interference and detection, a corresponding test verification method is proposed. The measurement is carried out in a closed laboratory environment, such as Figure 2 As shown above, all devices involved in the measurement are connected via coaxial cables instead of using antennas. This provides a controlled environment in which all interference sources are eliminated, except for the device under test. This also ensures accurate control and measurement of power levels during the measurement. In addition, radio channel effects, such as multipath propagation and fading, do not distort the measurement results. By testing in a closed environment as described above, it can be ensured that jammers will not adversely affect any nearby receivers.

[0069] The verification is mainly divided into two parts, one is to verify the transceiver, the other is the remote control system, and finally the analysis is performed based on the swept frequency interference suppression effect. In order to suppress the interference signal, a circulator is used immediately after the jammer and 30dB of attenuation is added to simulate the transmitting and receiving antennas with a spacing of about 70dB. In order to simulate the signal strength of different drone remote controllers, the remote control system uses a variable attenuator between the remote controller and the receiving front end. During the measurement process, the drone remote controller signal is attenuated in 5dB steps within the range of -80 to -110dB. The attenuation range is selected to make the remote control signal power eventually drop below the receiver noise floor.

[0070] In the presence of a frequency-hopping UAV remote control signal, the instantaneous frequency of the frequency-sweeping interference signal is estimated by a digital method, and the interference signal is suppressed by an adaptive filter, thereby effectively reducing interference while receiving the signal. The present invention can greatly suppress the interference in the target signal received by the UAV, and provides a powerful platform support and digital calculation method for military communication equipment to improve the robustness and signal reception accuracy of the wireless communication system in self-interference suppression and electronic attack scenarios.

[0071] The swept frequency interference suppression method proposed in the present invention combines instantaneous frequency estimation with adaptive filtering technology. By accurately reconstructing the interference signal and filtering it, efficient suppression is achieved without affecting the target signal, providing a strong guarantee for frequency hopping communication systems in complex electromagnetic environments.

[0072] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, the steps of the swept frequency interference suppression method for unmanned aerial vehicle remote control signals of any embodiment are implemented.

[0073] An embodiment of the present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the method for suppressing swept frequency interference of unmanned aerial vehicle remote control signals in any embodiment.

[0074] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0075] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0078] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for suppressing frequency sweep interference of UAV remote control signals, characterized in that: include: Estimate the instantaneous frequency of the chirp over the entire bandwidth of the drone remote controller signal; reconstructing the interference signal in the digital domain based on the estimated instantaneous power; The interference signal is subtracted from the drone remote controller signal through adaptive filtering.

2. The method for suppressing frequency sweep interference of a UAV remote control signal according to claim 1, characterized in that: Estimated instantaneous frequency for: in, is the phase value of the interference signal at time n, is the phase value of the interference signal at time n-1, x(n) is the value of the interference signal at time n, and x * (n-1) is the conjugate of the value of the interference signal at time n-1, is the instantaneous frequency estimated by the single difference operation.

3. The method for suppressing frequency sweep interference of a UAV remote control signal according to claim 2, characterized in that: The weighted phase difference estimator is used to estimate the instantaneous frequency, and the variance of the interference signal is reduced by using smoothing filtering and time averaging. For a stationary signal with a signal-to-noise ratio sufficient to reach the Cramer-Rao bound, the weighted phase difference estimator is given as: in, is the instantaneous frequency estimated by the weighted phase difference estimator, h n is the nth smoothing window, N The total size of the window.

4. The method for suppressing frequency sweep interference of a UAV remote control signal according to claim 3, characterized in that:

5. The method for suppressing frequency sweep interference of a UAV remote control signal according to claim 1, characterized in that: Reconstruct the interference signal x(t), x(t) as follows: Among them, A(t) is the instantaneous amplitude of the interference signal, w0 is a parameter related to the center frequency, φ0 is the initial phase, ψ is the sweep rate, t is time, j is the imaginary unit, and w0 is the local reconstruction. To assign a value.

6. The method for suppressing frequency sweep interference of a UAV remote control signal according to claim 1, characterized in that: For large signal-to-noise ratio scenarios, the normalized minimum mean square error method is used to update the filter taps of the adaptive filter to achieve the adaptive function.

7. A sweep frequency interference suppression device for UAV remote control signals, characterized in that: It includes an estimation module, a reconstruction module and an interference suppression module; wherein, An estimation module for estimating the instantaneous frequency of the linear frequency modulation over the entire bandwidth of the drone remote controller signal; A reconstruction module, configured to reconstruct the interference signal in a digital domain according to the estimated instantaneous power; Interference suppression module, used to subtract interference signals from the drone remote controller signal through adaptive filtering.

8. The device for suppressing frequency sweep interference of remote control signals of unmanned aerial vehicles according to claim 7, characterized in that: The FIR filter is used to realize adaptive filtering, and the adaptive filtering adopts the normalized least mean square algorithm NLMS to dynamically adjust the FIR filter parameters.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: When the processor executes the computer program, the steps of the method for suppressing frequency sweep interference of unmanned aerial vehicle remote control signals as described in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, the steps of the method for suppressing frequency sweep interference of unmanned aerial vehicle remote control signals as described in any one of claims 1 to 6 are implemented.

Images