CN114624736A - An anti-jamming method for Beidou time synchronization receiver - Google Patents
An anti-jamming method for Beidou time synchronization receiver Download PDFInfo
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Abstract
本发明公开了一种北斗时间同步接收机的抗干扰方法,其包括步骤:1)将接收机的射频前端处理模块输出的基带数字中频信号输入干扰抑制模块;2)干扰抑制模块采用频域干扰抑制算法抑制信号中的干扰;3)在授时解算前,剔除干扰抑制模块输出信号中的转发式干扰;4)在授时解算过程中,对尚未被发觉的转发式干扰信号用卡尔曼滤波算法进行滤除。本发明北斗时间同步接收机的抗干扰方法,其能有效的抑制窄带干扰和转发式干扰,可提高时间同步装置输出时间信息的准确性。
The invention discloses an anti-interference method for a Beidou time synchronization receiver, which comprises the steps of: 1) inputting a baseband digital intermediate frequency signal output by a radio frequency front-end processing module of the receiver into an interference suppression module; 2) the interference suppression module adopts frequency domain interference The suppression algorithm suppresses the interference in the signal; 3) Before the timing solution, remove the repeating interference in the output signal of the interference suppression module; 4) During the timing solution, use Kalman filter for the undiscovered repeating interference signal algorithm to filter out. The anti-jamming method of the Beidou time synchronization receiver of the present invention can effectively suppress narrowband interference and forwarding interference, and can improve the accuracy of the time information output by the time synchronization device.
Description
技术领域technical field
本发明涉及卫星导航授时应用技术领域,特别涉及一种北斗时间同步接收机的抗干扰方法。The invention relates to the technical field of satellite navigation timing applications, in particular to an anti-jamming method for a Beidou time synchronization receiver.
背景技术Background technique
随着卫星导航技术的发展及其应用领域的不断扩大,卫星授时技术已在电力、交通、通信、银行和金融等行业广泛应用。利用卫星授时可以实现广域范围的高精度时钟同步且成本低廉,特别是我国北斗卫星导航系统已正式投入运行,基于卫星时钟的同步技术在中国正发挥着越来越重要的作用,卫星授时型接收机的安全性日益突出。然而由于卫星发波功率有限,传输信道电磁干扰复杂,信号帧格式公开,卫星导航系统信号极易受到欺骗干扰。欺骗干扰会使时间同步装置输出错误的时间信息,会对生产运行的安全构成严重威胁。With the development of satellite navigation technology and the continuous expansion of its application fields, satellite timing technology has been widely used in electric power, transportation, communication, banking and finance industries. The use of satellite timing can achieve high-precision clock synchronization in a wide area with low cost. In particular, my country's Beidou satellite navigation system has been officially put into operation. The synchronization technology based on satellite clocks is playing an increasingly important role in China. The security of the receiver is becoming increasingly prominent. However, due to the limited power of satellite waves, the complex electromagnetic interference of the transmission channel, and the open signal frame format, the satellite navigation system signal is very vulnerable to deception interference. Spoofing interference will cause the time synchronization device to output wrong time information, which will pose a serious threat to the safety of production and operation.
发明内容SUMMARY OF THE INVENTION
有鉴于此,本发明的目的是提供一种北斗时间同步接收机的抗干扰方法,以解决电磁干扰影响时间同步装置输出时间信息准确性的技术问题。In view of this, the purpose of the present invention is to provide an anti-jamming method for a Beidou time synchronization receiver, so as to solve the technical problem that electromagnetic interference affects the accuracy of the time information output by the time synchronization device.
本发明北斗时间同步接收机的抗干扰方法包括以下步骤:The anti-jamming method of the Beidou time synchronization receiver of the present invention comprises the following steps:
1)将接收机的射频前端处理模块输出的基带数字中频信号输入干扰抑制模块;1) Input the baseband digital intermediate frequency signal output by the RF front-end processing module of the receiver into the interference suppression module;
2)干扰抑制模块采用频域干扰抑制算法抑制信号中的干扰,其又包括步骤:2) The interference suppression module adopts the frequency domain interference suppression algorithm to suppress the interference in the signal, which further comprises the steps:
2a)对输入信号进行串并变换;2a) Perform serial-parallel conversion on the input signal;
2b)对经串并变换后的信号进行加窗处理;2b) windowing the signal after serial-parallel conversion;
2c)对加窗处理后的信号进行FFT处理,将时域数据变换到频域;2c) FFT processing is performed on the windowed signal, and the time domain data is transformed into the frequency domain;
2d)经FFT处理后的信号,一路送入加权矢量生成单元以更新前一时段内生成的频域加权矢量,另一路与生成的频域加权矢量进行加权处理;2d) the signal after FFT processing is sent into the weighted vector generation unit all the way to update the frequency domain weighted vector generated in the previous period, and the other way is weighted with the generated frequency domain weighted vector;
2f)对经加权处理后的信号进行IFFT处理恢复出时域数据;2f) performing IFFT processing on the weighted signal to recover time domain data;
2g)对IFFT处理后的信号进行并串变换后输出,保持输入输出的数据速率不变;2g) output after parallel-serial conversion to the signal processed by IFFT, keeping the data rate of input and output unchanged;
3)在授时解算前,剔除干扰抑制模块输出信号中的转发式干扰,其又包括步骤:3) Before the timing calculation, remove the forwarding interference in the output signal of the interference suppression module, which further includes the steps:
3a)对信号的功率进行检测,剔除功率超出设定范围的信号;3a) Detect the power of the signal, and reject the signal whose power exceeds the set range;
3b)对信号的到达时间进行检测,剔除到达时间超出设定范围的信号;3b) Detect the arrival time of the signal, and reject the signal whose arrival time exceeds the set range;
3c)对电文信息进行检测,剔除电文信息异常的信号;3c) Detecting the message information, and eliminating the abnormal signal of the message information;
4)在授时解算过程中,对尚未被发觉的转发式干扰信号用卡尔曼滤波算法进行滤除。4) In the process of timing solution, Kalman filtering algorithm is used to filter out the undiscovered transponder interference signal.
进一步,所述步骤2d)中加权矢量生成单元生成频域加权矢量包括以下步骤:Further, in the described step 2d), the weighted vector generation unit to generate the frequency domain weighted vector includes the following steps:
2d1)对FFT处理后的信号取绝对值后平方;2d1) Take the absolute value of the FFT-processed signal and then square it;
2d2)将信号平均划分成若干段;2d2) Divide the signal into several segments evenly;
2d3)对每段分别计算其周期图,再取各个周期图的平均作为功率谱;2d3) Calculate its periodogram for each segment respectively, and then take the average of each periodogram as the power spectrum;
2d4)将功率谱的幅值与判决门限进行比较,生成频域加权矢量。2d4) Compare the magnitude of the power spectrum with the decision threshold to generate a frequency domain weighting vector.
进一步,在步骤2d)中将与频域加权矢量进行加权运算的一路信号进行白化滤波处理,白化滤波器为:Further, in step 2d), whitening filtering is performed on the one-way signal that is weighted with the frequency domain weighting vector, and the whitening filter is:
其中N0和NJ分别为噪声功率谱密度与干扰功率谱密度,f是信号频率,fI为干扰中心频率,B为噪声带宽,α为干扰带宽与噪声带宽的比例,j是窄带干扰信号;where N 0 and N J are the noise power spectral density and the interference power spectral density, respectively, f is the signal frequency, f I is the interference center frequency, B is the noise bandwidth, α is the ratio of the interference bandwidth to the noise bandwidth, and j is the narrowband interference signal ;
当干噪比远远大于1时,白化滤波器近似为When the dry-to-noise ratio is much greater than 1, the whitening filter is approximately
其中f0'是干扰频率;where f 0 ' is the interference frequency;
或者在步骤2d)中将与频域加权矢量进行加权运算的一路信号输入频域剔除器,将幅度超过干扰剔除门限的干扰谱线归零,所述频域剔除器由衰减因子等于的衰减器与式(2)中的白化滤波器级联组成,频域剔除器的传递函数为:Or in step 2d), the one-way signal that is weighted with the frequency domain weighting vector is input into the frequency domain culler, and the interference spectral line whose amplitude exceeds the interference culling threshold is zeroed, and the frequency domain culler is equal to the attenuation factor. The attenuator of , and the whitening filter in equation (2) are cascaded, and the transfer function of the frequency domain culler is:
本发明的有益效果:Beneficial effects of the present invention:
本发明北斗时间同步接收机的抗干扰方法,其能有效的抑制窄带干扰和转发式干扰,可提高时间同步装置输出时间信息的准确性。The anti-jamming method of the Beidou time synchronization receiver of the present invention can effectively suppress narrowband interference and forwarding interference, and can improve the accuracy of the time information output by the time synchronization device.
附图说明Description of drawings
图1为接收机系统框架图;从图中可知接收机系统主要包括三大部分,射频前端处理模块,干扰抑制模块和授时模块。天线将接收到混有噪声干扰的导航信号收集,传输到射频前端。射频模块在接收信号时,实现滤波、信号放大、下变频等功能。通过变频处理,将接收到的高频信号下变频到中频模拟信号。对降频后的信号通过多级带通滤波器将带外噪声去除掉,再由DSP软件或者其他信号处理器A/D采样,降低数据流速率,变成基带数字中频信号。Figure 1 is a frame diagram of the receiver system; it can be seen from the figure that the receiver system mainly includes three parts, the radio frequency front-end processing module, the interference suppression module and the timing module. The antenna collects the received navigation signal mixed with noise interference and transmits it to the RF front end. When the radio frequency module receives the signal, it realizes the functions of filtering, signal amplification, down-conversion and so on. Through frequency conversion processing, the received high-frequency signal is down-converted to an intermediate-frequency analog signal. The out-of-band noise is removed from the down-frequency signal through a multi-stage band-pass filter, and then sampled by DSP software or other signal processor A/D to reduce the data flow rate and become a baseband digital intermediate frequency signal.
图2为频域干扰抑制算法原理框图;Fig. 2 is the principle block diagram of the frequency domain interference suppression algorithm;
图3为频域加权矢量生成结构图;Fig. 3 is a structure diagram of frequency domain weighted vector generation;
图4为卫星导航系统接收机转发式干扰抑制算法流程图。FIG. 4 is a flowchart of a satellite navigation system receiver repeater interference suppression algorithm.
具体实施方式Detailed ways
下面结合附图和实施例对本发明作进一步描述。The present invention will be further described below with reference to the accompanying drawings and embodiments.
本实施例中北斗时间同步接收机的抗干扰方法主要解决抗窄带干扰和转发式欺骗干扰两个方面的问题。本实施例中北斗时间同步接收机的抗干扰方法包括以下步骤:The anti-jamming method of the Beidou time synchronization receiver in this embodiment mainly solves two problems of anti-narrowband interference and relay-type spoofing interference. The anti-jamming method of the Beidou time synchronization receiver in this embodiment includes the following steps:
1)将接收机的射频前端处理模块输出的基带数字中频信号输入干扰抑制模块。1) Input the baseband digital intermediate frequency signal output by the RF front-end processing module of the receiver into the interference suppression module.
2)干扰抑制模块采用频域干扰抑制算法抑制信号中的干扰,其又包括步骤:2) The interference suppression module adopts the frequency domain interference suppression algorithm to suppress the interference in the signal, which further comprises the steps:
2a)对输入信号进行串并变换。2a) Perform serial-to-parallel conversion on the input signal.
2b)对经串并变换后的信号进行加窗处理,以减小数据截断所引起的频谱泄露。本步骤需采用旁瓣电平较小的数据窗来减小频谱泄漏。从时域角度来看,加窗(常规FFT采用矩形窗)是对输入的数据进行窗函数加权;窗函数从中心向两端逐步衰减,可以保证前后段数据的连续性,从而达到减小频谱泄漏的目的。2b) Windowing the serial-to-parallel converted signal to reduce spectrum leakage caused by data truncation. In this step, a data window with a smaller side lobe level needs to be used to reduce spectral leakage. From the perspective of the time domain, windowing (regular FFT uses a rectangular window) is to weight the input data with a window function; the window function gradually decays from the center to both ends, which can ensure the continuity of the data in the front and back sections, thereby reducing the frequency spectrum. the purpose of the leak.
2c)对加窗处理后的信号进行FFT(fast Fourier transform,快速傅里叶变换)处理,将时域数据变换到频域。2c) Perform FFT (fast Fourier transform, fast Fourier transform) processing on the windowed signal to transform the time domain data into the frequency domain.
2d)经FFT处理后的信号,一路送入加权矢量生成单元以更新前一时段内生成的频域加权矢量,另一路与生成的频域加权矢量进行加权处理。2d) The signal after FFT processing is sent to the weighting vector generating unit in one way to update the frequency domain weighting vector generated in the previous period, and the other way is weighted with the generated frequency domain weighting vector.
频域加权矢量就是根据输入信号的功率谱密度确定干扰频带位置,并对被干扰的信号谱进行加权处理,从而达到干扰抑制的目的。The frequency domain weighting vector is to determine the position of the interference frequency band according to the power spectral density of the input signal, and weight the spectrum of the interfered signal, so as to achieve the purpose of interference suppression.
本步骤中,加权矢量生成单元生成频域加权矢量包括以下步骤:In this step, generating the frequency domain weighted vector by the weighted vector generating unit includes the following steps:
2d1)对FFT处理后的信号取绝对值后平方;2d1) Take the absolute value of the FFT-processed signal and then square it;
2d2)将信号平均划分成若干段;2d2) Divide the signal into several segments evenly;
2d3)对每段分别计算其周期图,再取各个周期图的平均作为功率谱;2d3) Calculate its periodogram for each segment respectively, and then take the average of each periodogram as the power spectrum;
2d4)将功率谱的幅值与判决门限进行比较,生成频域加权矢量。2d4) Compare the magnitude of the power spectrum with the decision threshold to generate a frequency domain weighting vector.
本步骤中,将与频域加权矢量进行加权运算的一路信号进行白化滤波处理,白化滤波器为:In this step, whitening filtering is performed on one signal that is weighted with the frequency domain weighting vector, and the whitening filter is:
其中N0和NJ分别为噪声功率谱密度与干扰功率谱密度,f是信号频率,fI为干扰中心频率,B为噪声带宽,α为干扰带宽与噪声带宽的比例,j是窄带干扰信号。where N 0 and N J are the noise power spectral density and the interference power spectral density, respectively, f is the signal frequency, f I is the interference center frequency, B is the noise bandwidth, α is the ratio of the interference bandwidth to the noise bandwidth, and j is the narrowband interference signal .
当干噪比远远大于1时,白化滤波器近似为When the dry-to-noise ratio is much greater than 1, the whitening filter is approximately
其中f0'是干扰频率。where f 0 ' is the interference frequency.
此时,白化滤波器相当于从频谱上将干扰频带内的干扰、噪声和信号完全滤除掉,而对干扰频带外的噪声功率谱进行归一化处理。白化滤波器置于接收机的匹配滤波器之前。At this time, the whitening filter is equivalent to completely filtering out the interference, noise and signals in the interference band from the spectrum, and normalizing the noise power spectrum outside the interference band. The whitening filter is placed before the matched filter of the receiver.
或者在步骤2d)中还可将与频域加权矢量进行加权运算的一路信号输入频域剔除器,将幅度超过干扰剔除门限的干扰谱线归零,所述频域剔除器由衰减因子等于的衰减器与式(2)中的白化滤波器级联组成,频域剔除器的传递函数为:Or in step 2d), the one-way signal that is weighted with the frequency domain weighting vector can also be input into the frequency domain culler, and the interference spectral line whose amplitude exceeds the interference culling threshold is returned to zero, and the frequency domain culler is equal to the attenuation factor. The attenuator of , and the whitening filter in equation (2) are cascaded, and the transfer function of the frequency domain culler is:
频域剔除器具体是利用大谱线归零原理,将幅度超过干扰剔除门限的干扰谱线归零,而其它谱线保持不变,从而达到干扰抑制的目的。从滤波器角度来看,频域干扰剔除算法相当于具有零相位响应的理想带阻滤波器,算法时延等于0,可免除时延估算过程。The frequency domain culler specifically uses the principle of returning to zero for large spectral lines to zero the interference spectral lines whose amplitude exceeds the interference rejection threshold, while the other spectral lines remain unchanged, so as to achieve the purpose of interference suppression. From the filter point of view, the frequency-domain interference rejection algorithm is equivalent to an ideal band-stop filter with zero-phase response, and the algorithm delay is equal to 0, which can avoid the delay estimation process.
2f)对经加权处理后的信号进行IFFT(Inverse Fast Fourier Transform,快速傅里叶逆变换)处理恢复出时域数据。2f) Perform IFFT (Inverse Fast Fourier Transform, Inverse Fast Fourier Transform) processing on the weighted signal to recover time domain data.
2g)对IFFT处理后的信号进行并串变换后输出,保持输入输出的数据速率不变。2g) Perform parallel-to-serial transformation on the IFFT-processed signal and output it, keeping the data rate of the input and output unchanged.
通过频域干扰抑制算法可以实现对窄带干扰的抑制,无杂散动态范围可以达到88dB。The narrowband interference can be suppressed by the frequency domain interference suppression algorithm, and the spurious-free dynamic range can reach 88dB.
3)在授时解算前,剔除干扰抑制模块输出信号中的转发式干扰,其又包括步骤:3) Before the timing calculation, remove the forwarding interference in the output signal of the interference suppression module, which further includes the steps:
3a)对信号的功率进行检测,剔除功率超出设定范围的信号。虽然转发式干扰信号与卫星信号的强度相当,具有极高的隐蔽性,但是转发式干扰信号的强度要略大于真实卫星信号强度,因为只有这样才能使干扰信号在接收机的捕获过程中占据优势。受到星上发射功率范围的影响,接收机接收到的卫星信号功率具有一个正常合理的工作范围,即-110dBm~-133dBm,因此,如果接收到的导航卫星信号功率超出了这个范围,就可以认为该信号为转发式干扰信号。3a) Detect the power of the signal, and reject the signal whose power exceeds the set range. Although the strength of the repeater jamming signal is equal to that of the satellite signal, it has extremely high concealment, but the strength of the repeater jamming signal is slightly larger than that of the real satellite signal, because only in this way can the jamming signal have an advantage in the receiver's acquisition process. Affected by the transmission power range on the satellite, the satellite signal power received by the receiver has a normal and reasonable working range, namely -110dBm ~ -133dBm. Therefore, if the received navigation satellite signal power exceeds this range, it can be considered that This signal is a repeating interference signal.
导航卫星信号功率的估计,主要是依据相关通道的积分数值大小来判别,即相关通道输出功率。也就是说,利用三路积分支路(超前、滞后和当前)中当前支路的功率(积分值平方和)除以噪声功率。噪声功率计算方法如下:The estimation of the signal power of the navigation satellite is mainly based on the integral value of the relevant channel, that is, the output power of the relevant channel. That is, the noise power is divided by the power of the current branch (the sum of the squares of the integral values) in the three-way integrating branch (lead, lag, and current). The noise power calculation method is as follows:
由于在通常的导航接收机中A/D模数转换器件前端存在AGC自动增益控制作用,可以基本保持输入信号强度保持不变,如果A/D采用3比特量化,那么可以设定模拟输入信号经过量化后的信号幅度保持的概率分布为:Due to the AGC automatic gain control function in the front end of the A/D analog-to-digital conversion device in the usual navigation receiver, the input signal strength can be basically kept unchanged. If the A/D adopts 3-bit quantization, the analog input signal can be set to pass through The probability distribution of the quantized signal amplitude preservation is:
而本地载波恢复采用的本地载波也是使用3bit量化,其量化方法如下:The local carrier used for local carrier recovery also uses 3bit quantization, and the quantization method is as follows:
I支路或Q支路:+2+2+1-1-2-2-1+1I branch or Q branch: +2+2+1-1-2-2-1+1
当没有信号输入情况下,计算本地载波信号与输入信号的乘积结果,当输入信号幅度为如下几种情况时:When there is no signal input, calculate the result of the product of the local carrier signal and the input signal. When the input signal amplitude is as follows:
(i)输入信号幅度:+3(i) Input signal amplitude: +3
与本地载波信号相乘结果:+6+6+3-3-6-6-3+3Multiplication result with the local carrier signal: +6+6+3-3-6-6-3+3
乘积结果均方值:22.5The mean square value of the product result: 22.5
(ii)输入信号幅度:+1(ii) Input signal amplitude: +1
与本地载波信号相乘结果:+2+2+1-1-2-2-1+1Multiplication result with the local carrier signal: +2+2+1-1-2-2-1+1
乘积结果均方值:2.5The mean square value of the product result: 2.5
由于单次计算的受噪声的影响,存在较大的浮动,因此可以采用多次统计计算其均值,从而得到更为精确的信号功率估计。另外,也可以将单次通过一个低通滤波器滤波,从而可以得到准确的信号功率估计值。Due to the influence of noise in a single calculation, there is a large fluctuation, so multiple statistical calculations can be used to calculate the mean value, so as to obtain a more accurate signal power estimate. In addition, the single pass can also be filtered by a low-pass filter, so that an accurate estimate of the signal power can be obtained.
3b)对信号的到达时间进行检测,剔除到达时间超出设定范围的信号。由于星座布局不同,不同卫星的信号到达时(TOA)不同,考虑到卫星与地面接收机时钟存在偏差,因此不能对信号到达时的范围进行有效限定,从而判断接收信号是否为转发式干扰。但是由于星座模型是固定的,因此不同卫星信号的到达时之差,即到达时的相对值,具有一个合理范围,因此可以通过仿真建立星座模型,得到卫星之间到达时的相对值范围,当接收信号超过这个范围时,可以认定为转发式干扰信号。3b) Detect the arrival time of the signal, and reject the signal whose arrival time exceeds the set range. Due to different constellation layouts and different time-of-arrival (TOA) of signals from different satellites, considering the clock deviation between the satellite and the ground receiver, it is not possible to effectively limit the range of the signal when it arrives, so as to determine whether the received signal is transponder interference. However, because the constellation model is fixed, the difference between the arrival times of different satellite signals, that is, the relative value at arrival, has a reasonable range. Therefore, the constellation model can be established by simulation to obtain the relative value range between satellites. When When the received signal exceeds this range, it can be regarded as a repeater interference signal.
下面介绍如何设定这个卫星到达时之差的合理范围。仿真以北斗系统为例,卫星轨道半径约为26561.750公里,地球半径约为6378公里。接收机处于不同的经度(0°~360°)和纬度(0°~180°)的情况下(海拔为0度),在一个轨道周期(0°~360°)内,仿真得知卫星到达时之差的最大值随经度变化不明显,但是随纬度变化明显,而且其纬度越接近极点,到达时之差的最大值越小,不同卫星到达时之差的最大值为17.7ms。不同应用背景的接收机对应一个海拔高度范围,当接收机的海拔高度变化时,接收机在所有经纬度位置上的卫星到达时之差的最大值进行仿真可知,接收机海拔越高,卫星到达时之差的最大值越大,每增加100km的海拔高度,卫星到达时之差的最大值增加0.22ms。由于这里考虑进行的是一步简单有效的判别,针对的是较为明显的低质量转发式干扰信号,而且由于近地接收机的海拔高度范围在几百公里,因此这里设定关于卫星到达时之差的最大值判别门限为20ms,做初步判决甄别,当接收到的卫星信号与其它可视卫星信号的到达时之差超出这个范围时,可以认为该信号为转发式干扰信号。The following describes how to set a reasonable range for the difference in arrival time of this satellite. The simulation takes the Beidou system as an example, the satellite orbit radius is about 26561.750 kilometers, and the earth radius is about 6378 kilometers. When the receiver is at different longitude (0°~360°) and latitude (0°~180°) (the altitude is 0°), within one orbital period (0°~360°), the simulation knows that the satellite arrives The maximum value of the time difference does not change significantly with longitude, but it changes significantly with latitude, and the closer the latitude is to the pole, the smaller the maximum time difference of arrival, and the maximum difference between the arrival times of different satellites is 17.7ms. Receivers with different application backgrounds correspond to an altitude range. When the altitude of the receiver changes, the maximum difference between the arrival times of satellites at all latitude and longitude positions of the receiver is simulated. The higher the receiver altitude, the higher the satellite arrival time. The larger the maximum value of the difference is, the maximum value of the difference when the satellite arrives increases by 0.22ms for every 100km of altitude increase. Since what is considered here is a simple and effective judgment, it is aimed at relatively obvious low-quality retransmission interference signals, and because the altitude range of the near-earth receiver is hundreds of kilometers, so the difference between the arrival time of the satellite is set here. The maximum judgment threshold is 20ms, and a preliminary judgment is made. When the difference between the arrival time of the received satellite signal and other visible satellite signals exceeds this range, it can be considered that the signal is a transponder interference signal.
3c)对电文信息进行检测,剔除电文信息异常的信号。转发式干扰信号引入的导航电文信息误差,包括旨在引起卫星位置错误的卫星星历误差和卫星时钟修正误差,以及旨在引起卫星伪距值偏差的伪距校正量误差(包括电离层延迟误差修正)。卫星星历、卫星时钟修正值和电离层延迟误差修正值都是由导航电文中相应参数计算得出,这些参数具有经验量级以及经验范围,因此,采用电文信息监测判别方法,在定位解算之前,可将具有这种明显干扰特征的转发式干扰信号剔除。3c) Detecting the message information, and eliminating the abnormal signal of the message message. Navigation message information errors introduced by repeater jamming signals, including satellite ephemeris errors and satellite clock correction errors designed to cause satellite position errors, and pseudorange correction errors (including ionospheric delay errors) designed to cause deviations in satellite pseudorange values. correction). The satellite ephemeris, satellite clock correction value and ionospheric delay error correction value are all calculated from the corresponding parameters in the navigation message. These parameters have an empirical magnitude and an empirical range. Previously, repeater jammers with such obvious jamming characteristics could be rejected.
4)在授时解算过程中,对尚未被发觉的转发式干扰信号用卡尔曼滤波算法进行滤除。在步骤3b)中,对于在模糊度范围之内的干扰信号,判决门限不能识别,本步骤通过在接收机的信息处理阶段用抗转发式干扰卡尔曼滤波算法进行滤除。4) In the process of timing solution, Kalman filtering algorithm is used to filter out the undiscovered transponder interference signal. In step 3b), for the interference signal within the ambiguity range, the decision threshold cannot be identified, and this step is filtered by using the anti-relay interference Kalman filter algorithm in the information processing stage of the receiver.
最后说明的是,以上实施例仅用以说明本发明的技术方案而非限制,尽管参照较佳实施例对本发明进行了详细说明,本领域的普通技术人员应当理解,可以对本发明的技术方案进行修改或者等同替换,而不脱离本发明技术方案的宗旨和范围,其均应涵盖在本发明的权利要求范围当中。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.
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