阅读说明：本技术 一种低功耗导航接收机抗干扰方法 (Anti-interference method for low-power-consumption navigation receiver ) 是由 张柏华 刘俊秀 周显文 石岭 于 2019-10-25 设计创作，主要内容包括：本发明提供一种低功耗导航接收机抗干扰方法,包括：捕获状态时,对接收数据进行频域抗干扰处理；跟踪状态时,每间隔预设时长对接收数据利用快速傅里叶变换进行定期干扰检测,对判定存在干扰的接收数据进行时域陷波器滤波处理。本发明提供的抗干扰方法可以有效提高单个接收天线抗多音干扰的能力同时有助于降低接收机功耗。(The invention provides an anti-interference method of a low-power-consumption navigation receiver, which comprises the following steps: when in a capture state, performing frequency domain anti-interference processing on received data; and in the tracking state, performing periodic interference detection on the received data by using fast Fourier transform at preset time intervals, and performing time domain trap filter processing on the received data judged to have interference. The anti-interference method provided by the invention can effectively improve the multi-tone interference resistance of a single receiving antenna and is beneficial to reducing the power consumption of the receiver.)

1. An anti-interference method for a low-power-consumption navigation receiver is characterized by comprising the following steps:

when in a capture state, performing frequency domain anti-interference processing on received data;

and in the tracking state, performing periodic interference detection on the received data by using fast Fourier transform at preset time intervals, and performing time domain trap filter processing on the received data judged to have interference.

2. The method for resisting interference of a low-power-consumption navigation receiver of claim 1, wherein the preset duration is 10-20 ms.

3. The method according to claim 1, wherein the performing frequency-domain interference rejection processing on the received data in the capture state specifically includes:

transforming the received data to a frequency domain through fast Fourier transform;

calculating the current interference threshold in real time according to the data after the fast Fourier transform processing;

when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the power corresponding to the frequency point to zero;

and transforming the frequency domain signal into a time domain through inverse fast Fourier transform.

4. The method for resisting interference of a low-power-consumption navigation receiver according to claim 1, wherein the step of performing periodic interference detection on the received data by using fast fourier transform at preset intervals in the tracking state specifically includes:

periodically performing fast Fourier transform on received data every preset time interval;

calculating the current interference threshold in real time according to the data after the fast Fourier transform processing;

and when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the frequency point as a trapped wave frequency point of the time domain trap filter.

5. The antijamming method for a low-power-consumption navigation receiver according to any one of claims 3 or 4, wherein the preset threshold is updated adaptively; the initial value of the preset threshold is obtained by multiplying the average value calculated by the fast Fourier transform results of a plurality of periods by a preset coefficient; the preset threshold is continuously updated according to the obtained data after the fast Fourier transform processing: and if the data obtained after the fast Fourier transform processing is less than or equal to the current preset threshold, performing iterative weighted summation on the current preset threshold and the data obtained after the fast Fourier transform processing.

6. The method of claim 1, wherein the time domain traps each employ a 2 nd order IIR trap.

7. The method of claim 6, wherein the transfer function of the 2 nd order IIR trap is expressed as follows:

wherein, ω is₀＝2πf₀/f_s，f₀To trap the frequency of the point, f_sFor the sampling frequency, r is 0.98.

8. The method of claim 4, wherein the setting the frequency point as a notch frequency point of the time domain trap specifically comprises:

when the number of the time domain wave traps is larger than or equal to the number of frequency points corresponding to the interference signals, setting the frequency point of each interference signal as the wave trap point frequency of each time domain wave trap;

when the number N of the time domain wave traps is smaller than the number of frequency points corresponding to the interference signals, arranging the frequency points of the interference signals from large to small according to the interference intensity; and respectively setting N frequency points before sequencing as the trap wave point frequency of each time domain trap.

9. The method of claim 8, wherein the number of time domain traps is 5, and wherein the 5 time domain traps are arranged in a cascade.

Technical Field

The invention relates to the technical field of single-antenna satellite navigation, in particular to an anti-interference method of a low-power-consumption navigation receiver.

Background

The use of navigation systems is becoming widespread, and has now penetrated the way in which people live, from the first military purpose to the subsequent civilian use as a primary aspect. Meanwhile, the navigation system is fragile, the satellite navigation signal is very weak, and is often only 160dBW when reaching the ground, so that the navigation system is very easy to be interfered by various purposes and accidents. Experiments show that the jammer with the power of 1W can enable a C/A code receiver within 85km to be incapable of working, and the current GPS jammer with the power of 4W can enable an onboard GPS receiver to be interfered beyond 145 km. Therefore, in the face of increasingly complex electronic environments, the navigation system faces a severe safety problem in the future informatization war, and it is particularly urgent to improve the anti-interference capability of the navigation system. Particularly, how to improve the anti-interference capability and reduce the cost of a navigation receiver with a single receiving antenna is a problem to be solved urgently.

Disclosure of Invention

In view of the above, the present invention provides an anti-interference method for a low power consumption navigation receiver to solve the existing disadvantages.

In order to achieve the purpose, the invention adopts the following technical scheme:

the embodiment of the invention provides an anti-interference method for a low-power-consumption navigation receiver, which comprises the following steps:

when in a capture state, performing frequency domain anti-interference processing on received data;

and in the tracking state, performing periodic interference detection on the received data by using fast Fourier transform at preset time intervals, and performing time domain trap filter processing on the received data judged to have interference.

Further, the preset time is 10-20 ms.

Further, the step of performing frequency domain anti-interference processing on the received data in the capture state specifically includes:

transforming the received data to a frequency domain through fast Fourier transform;

calculating the current interference threshold in real time according to the data after the fast Fourier transform processing;

when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the power corresponding to the frequency point to zero;

and transforming the frequency domain signal into a time domain through inverse fast Fourier transform.

Further, the "performing periodic interference detection on the received data by using fast fourier transform every preset time interval in the tracking state" specifically includes:

periodically performing fast Fourier transform on received data every preset time interval;

calculating the current interference threshold in real time according to the data after the fast Fourier transform processing;

and when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the frequency point as a trapped wave frequency point of the time domain trap filter.

Further, the preset threshold is updated in a self-adaptive mode; the initial value of the preset threshold is obtained by multiplying the average value calculated by the fast Fourier transform results of a plurality of periods by a preset coefficient; the preset threshold is continuously updated according to the obtained data after the fast Fourier transform processing: and if the data obtained after the fast Fourier transform processing is less than or equal to the current preset threshold, performing iterative weighted summation on the current preset threshold and the data obtained after the fast Fourier transform processing.

Further, the time domain wave traps all adopt 2-order IIR wave traps.

Further, the transfer function of the 2 nd order IIR trap adopts the following expression:

wherein, ω is₀＝2πf₀/f_s，f₀To trap the frequency of the point, f_sFor the sampling frequency, r is 0.98.

Further, the setting the frequency point as a notch frequency point of the time domain notch filter specifically includes:

when the number of the time domain wave traps is larger than or equal to the number of frequency points corresponding to the interference signals, setting the frequency point of each interference signal as the wave trap point frequency of each time domain wave trap;

when the number N of the time domain wave traps is smaller than the number of frequency points corresponding to the interference signals, arranging the frequency points of the interference signals from large to small according to the interference intensity; and respectively setting N frequency points before sequencing as the trap wave point frequency of each time domain trap.

Further, the number of the time domain wave traps is 5, and the 5 time domain wave traps are arranged in a cascade mode.

Based on the scheme provided by the invention, the anti-interference of the navigation receiver of a single receiving antenna is organically combined with frequency domain interference detection and time domain filtering, so that the anti-interference performance can be effectively improved, and meanwhile, the fast Fourier transform module is called once at intervals of a period of time in a tracking state, so that the calculation amount is small, and the power consumption is low.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart of an anti-interference method for a low power consumption navigation receiver according to an embodiment of the present invention;

fig. 2 is a flowchart illustrating a frequency domain anti-interference process performed on received data in a capture state according to an embodiment of the present invention;

fig. 3 is a flowchart of performing periodic interference detection on received data by using fast fourier transform at preset time intervals in a tracking state according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, an embodiment of the present invention provides an anti-interference method for a low power consumption navigation receiver, including:

s101, in the capture state, performing frequency domain anti-interference processing on the received data.

As shown in fig. 2, the step of performing frequency domain anti-interference processing on the received data in the capture state specifically includes:

and S1011, carrying out fast Fourier transform on the received data to a frequency domain.

And S1012, calculating the current interference threshold in real time according to the data after the fast Fourier transform processing.

And S1013, when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the power corresponding to the frequency point to zero.

The preset threshold is updated in a self-adaptive mode; the initial value of the preset threshold is obtained by multiplying the average value calculated by the fast Fourier transform results of a plurality of periods by a preset coefficient, and the preset threshold is continuously updated according to the obtained data after the fast Fourier transform processing: and if the data obtained after the fast Fourier transform processing is less than or equal to the current preset threshold, performing iterative weighted summation on the current preset threshold and the data obtained after the fast Fourier transform processing.

And S1014, transforming the frequency domain signal to a time domain through inverse fast Fourier transform.

And calculating the current interference threshold in real time according to the data subjected to the fast Fourier transform, if the interference threshold does not exceed the preset threshold, not processing, not performing inverse fast Fourier transform, and directly outputting the data before the fast Fourier transform to the rear end for processing.

S102, in the tracking state, regular interference detection is carried out on the received data by using fast Fourier transform at intervals of preset time, and filtering processing of a time domain trap is carried out on the received data judged to have interference.

The preset time is 10-20 ms.

As shown in fig. 3, the "performing periodic interference detection on received data by using fast fourier transform at preset intervals in the tracking state" specifically includes:

and S1021, periodically performing fast Fourier transform on the received data at preset time intervals. The preset time is 10-20 ms.

And S1022, calculating the current interference threshold in real time according to the data subjected to the fast Fourier transform.

And S1023, when the interference threshold exceeds a preset threshold, acquiring a frequency point corresponding to the current interference signal and setting the frequency point as a trapped wave frequency point of the time domain trap filter.

The preset threshold is updated in a self-adaptive mode; the initial value of the preset threshold is obtained by multiplying the average value calculated by the fast Fourier transform results of a plurality of periods by a preset coefficient, and the preset threshold is continuously updated according to the obtained data after the fast Fourier transform processing: and if the data obtained after the fast Fourier transform processing is less than or equal to the current preset threshold, performing iterative weighted summation on the current preset threshold and the data obtained after the fast Fourier transform processing.

The time domain wave trap is suitable for real-time high-speed signal processing in broadband spread spectrum communication and navigation systems due to simple hardware implementation. When the interference signal is in the passband of the useful signal, the notch filter suppresses the interference signal and also distorts the spectrum and waveform of the useful signal, and the distortion degree depends on the type of the notch filter and the notch frequency point (i.e., the interference frequency point). The 2-order FIR notch filter has linear phase characteristics, but the notch characteristics are not sharp enough, and the attenuation effect on useful signal energy is great; while IIR notch filters have sharp notch characteristics and little attenuation of the useful signal energy, they have nonlinear phase characteristics. When the interference signal is in the passband of the useful signal, whether it be an IIR or FIR notch filter, it will also distort the spectrum and waveform of the useful signal while suppressing the interference signal. Meanwhile, the calculation amount of the high-order cascade of the wave traps is higher than that of the high-order cascade of the wave traps, and the high-order IIR wave trap is relatively complex. And the complexity and the performance index of the system are comprehensively considered, and a 2-order IIR wave trap is the best choice. Therefore, the time domain wave traps adopt 2-order IIR wave traps. The transfer function of the 2 nd order IIR wave trap adopts the following expression:

wherein, ω is₀＝2πf₀/f_s，f₀To trap the frequency of the point, f_sFor the sampling frequency, the value of r may determine the notch width and depth. The smaller the value of r is, the wider the notch width is, and the deeper the notch depth is; the larger the value of r is, the narrower the notch width is, and the shallower the notch depth is; when the value of r is 1, it is an all-pass filter, and the value of r in the application is preferably 0.98.

The step of setting the frequency point as a trap frequency point of the time domain trap specifically comprises the following steps:

when the number of the time domain wave traps is larger than or equal to the number of frequency points corresponding to the interference signals, setting the frequency point of each interference signal as the wave trap point frequency of each time domain wave trap; when the number N of the time domain wave traps is smaller than the number of frequency points corresponding to the interference signals, arranging the frequency points of the interference signals from large to small according to the interference intensity; and respectively setting N frequency points before sequencing as the trap wave point frequency of each time domain trap.

The number of the time domain wave traps is 5, and the 5 time domain wave traps are arranged in a cascade mode.

By adopting the anti-interference method provided by the application, the anti-interference capability of the single-antenna navigation receiver in the capturing and tracking states is greatly improved, the multi-tone interference with the interference-to-signal ratio of 60dB can be effectively resisted, meanwhile, because the FFT module is called once within 10-20 milliseconds in the tracking state, if the sampling frequency is 64MHz and the number of FFT points is 4096, the FFT calculation amount in the tracking state is only about 1/320-1/160 of the FFT calculation amount which continuously works, and correspondingly, the power consumption is also reduced by 2-3 orders of magnitude. The application is a suitable choice in the aspects of low cost, low complexity, low power consumption and high interference resistance.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.