CN109031438A - Anti-interference method and system for multi-channel receiver - Google Patents

Abstract

The invention discloses a kind of anti-interference methods and system for multi-channel receiver, which comprises synchronizes superposition processing to multi-channel receiver received signal；Comb filtering processing is carried out to the signal after the synchronized superposition processing；α-Trimed filtering processing is carried out to the signal handled through comb filtering.The anti-interference method and system of multi-channel receiver described in the embodiment of the present invention, by introducing three kinds of filtering techniques, a variety of interference in signal can be filtered out, realizes and broadband weak signal is acquired and handles art, improve the accuracy of electrical prospecting method and electrical measuring instrument,.

Description

Anti-interference method and system for multi-channel receiver

technical field

The invention relates to the detection field, in particular to an anti-jamming method and system for a multi-channel receiver.

Background technique

Electrical prospecting is one of the effective means of mineral resource exploration. It has various types and strong adaptability, and is widely used in deep structure detection, mineral resource exploration, hydrological and engineering exploration and other fields.

According to the nature of field sources, electrical prospecting can be divided into natural source methods and artificial source methods. Among the natural source methods, the magnetotelluric method (Magnetotelluric, MT) is currently the electrical prospecting method with the largest detection depth. Controlled Source Audio-frequency Magnetotelluric (CSAMT) replaces natural field sources with artificial field sources, and follows the observation method of MT, but overcomes the shortcomings of randomness of MT field sources, and greatly improves the signal strength. Except that the detection depth is smaller than that of MT, its work efficiency, precision and horizontal and vertical resolution are all significantly improved.

Existing electrical prospecting methods and electrical prospecting instruments usually use multi-channel receivers, but the accuracy of the existing electrical prospecting methods is still not high, because the interference generated by the external environment is large, and it is difficult to extract useful signals. External interference mainly includes random interference generated by the environment, power frequency interference generated by power lines, and spike interference generated by electric sparks. The anti-jamming method in the prior art still has great deficiencies, and the interference is too large, resulting in low accuracy of electrical prospecting.

Contents of the invention

In view of this, the embodiment of the present application provides an anti-interference method and system for a multi-channel receiver, which can filter out various interferences in the signal, and improve the accuracy of the electrical prospecting method and the electrical prospecting instrument. On the one hand, the embodiment provides an anti-jamming method for a multi-channel receiver, the method performs synchronous superposition processing on signals received by the multi-channel receiver; comb filter processing is performed on the signal after synchronous superposition processing ; performing α-Trimed filter processing on the comb filter processed signal.

Optionally, performing synchronous superposition processing on the signal received by the multi-channel receiver includes: dividing the signal received by the multi-channel receiver into multiple signal segments; dividing the signal in each signal segment into multiple signal segments ; Superimpose multiple signal sections in each signal segment to obtain amplitude and phase information of the signal segment; superimpose multiple superimposed signal segments to obtain amplitude and phase information of the multi-channel received signal .

Optionally, performing comb filter processing on the signal after synchronous superposition processing includes: delaying the signal received by the multi-channel receiver to become a delayed signal; combining the signal received by the multi-channel receiver with The delayed signals are added to produce phase cancellation.

Optionally, performing comb filter processing on the synchronously superimposed signal includes: using an FPGA with a multiplier-adder to implement comb filter processing on signals received by the multi-channel receiver.

Optionally, performing comb filter processing on the signal after synchronous superposition processing includes: using multiple FPGA cascades with multiplier-adders to implement comb filter processing on signals received by the multi-channel receiver .

Optionally, performing α-Trimed filter processing on the signal processed by comb filtering, including: setting window length N and parameter α, wherein α represents the percentage of trimmed data samples; according to window length N and parameter α, for The signal received by the multi-channel receiver is processed; the window is moved by one element to process the signal received by the multi-channel receiver.

Optionally, the processing the signal received by the multi-channel receiver according to the window length N and the parameter α includes: filtering out redundant data according to the window length N and the parameter α; performing averaging processing on the remaining data.

Optionally, before performing α-Trimed filtering on the comb-filtered signal, the method further includes: acquiring a value corresponding to the signal received by the multi-channel receiver; adding additional signals at the beginning and end of the signal respectively , and the added additional signal is a symmetrical addition; the values corresponding to the signals received by the multi-channel receiver are sorted from small to large.

Optionally, adding additional signals to the signal header and the signal tail respectively, including: if the window length N is an even number, adding N/2 data to the signal header and the signal tail respectively; if the window length N is If the number is odd, add (N-1)/2 data to the signal head and signal tail respectively.

Another aspect of the embodiment of the present invention provides an anti-jamming system for a multi-channel receiver, the system includes: a synchronous superposition filter for synchronous superposition processing on signals received by the multi-channel receiver; A filter is used to perform comb filter processing on the signal processed by synchronous superposition; an α-Trimed filter is used to perform α-Trimed filter processing on the signal processed by comb filter.

The anti-jamming method and system of the multi-channel receiver described in the embodiment of the present invention can filter out various kinds of interference in the signal by introducing three kinds of filtering techniques, realize the acquisition and processing of wide-band weak signals, and improve the electrical method. Accuracy of prospecting methods and electrical prospecting instruments.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings that need to be used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a flowchart of an anti-jamming method for a multi-channel receiver provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of performing synchronous superposition processing on signals received by a multi-channel receiver according to an embodiment of the present invention;

Fig. 3 shows the schematic diagram of the FPGA multiply-accumulator of the embodiment of the present invention;

FIG. 4 is a schematic diagram of a state machine of a comb filter according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of one-dimensional signal extension according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of two-dimensional signal extension according to an embodiment of the present invention;

FIG. 7 is a schematic flowchart of α-trimmed filter filtering according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should also be noted that, unless otherwise specified and limited, the terms "set", "coupled" and "connected" should be interpreted in a broad sense, for example, "connected" can be a direct connection, or It can be connected indirectly through an intermediary, or it can be an internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In this document, relational terms such as first and second etc. are used only to distinguish one entity or operation from another without necessarily requiring or implying any such relationship between these entities or operations. Actual relationship or sequence. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The embodiment of the present invention discloses an anti-jamming method for a multi-channel receiver, the method comprising:

S110, performing synchronous superposition processing on signals received by the multi-channel receiver;

S120, performing comb filter processing on the signal after synchronous superposition processing;

S130. Perform α-Trimed filtering on the comb-filtered signal.

The superimposed average processing technology is an effective noise-removing signal processing method. The embodiment of the present invention utilizes the high-precision synchronous clock of the system to realize the superimposed filtering technology of the hardware circuit. Specifically, as shown in Figure 2, the synchronous superposition processing of the original signal received by the multi-channel receiver includes:

S111, divide the original signal received by the multi-channel receiver into multiple signal segments;

S112. Divide the signal in each signal segment into multiple signal segments;

S113. Superimpose multiple signal segments in each signal segment to obtain amplitude and phase information of the signal segment;

S114. Superimpose multiple superimposed signal segments, and acquire amplitude and phase information of signals received by the multi-channels.

The process of superimposing signals is as follows. In the original input signal, both useful signals and random interference are included:

Suppose the original input signal is f(t), which can be expressed as f(t)=s(t)+n(t).

Among them, s(t) is a periodic signal with constant amplitude, and n(t) is random interference.

The random disturbance n(t) obeys Gaussian distribution, its mean is zero, and its variance is δ ² , which is also called Gaussian white noise. According to the properties of Gaussian white noise, it can be known that the power of this noise is δ ² , that is, the signal-to-noise ratio of the input signal is:

SNR _in = S/δ ²

S is the total power. After m times of stacking and averaging, the output signal is:

In the formula, T is the time interval, f(tk+iT) is the Kth sample value of the i-th point, and n(t) is the effective value of the noise signal. The above-mentioned superposition and average processing is performed on the input signal, and the value of the effective signal remains unchanged after m times of superposition and averaging, while the noise superposition and averaging becomes:

Then the output signal-to-noise ratio becomes:

In the formula, N _O is the power of the output noise after superposition and averaging.

After the signal superposition processing described in the embodiment of the present invention is adopted, after the periodic signal is synchronously superimposed m times, the signal-to-noise ratio is increased to m times of the original. Therefore, the signal-to-noise ratio of a periodic signal or repeatable signal will continue to improve after multiple sampling accumulations, and the more times of accumulation, the better the signal-to-noise ratio improvement. In order to extract a weak signal from a background of strong noise, preferably, the average number of superposition times is greater than 50.

In one embodiment of the present invention, in order to further improve the signal-to-noise ratio in a scene where 50 Hz power frequency interference is relatively large, a step of analog filtering is performed on the analog signal before step S110 is performed. Considering that the precision of the analog filter is low, and the damage to the useful signal in the frequency range of about 50 Hz is relatively large, step S120 is further set to filter the digital signal after step S110 is completed, and the digital filter can be designed with reasonable coefficients in While completing high-precision filtering, there is less damage to useful signals in the frequency range of about 50Hz.

In the embodiment of the present invention, in step S120, comb filter processing is performed on the signal after synchronous superposition processing, including:

S121. Delay the synchronously superimposed signal to become a delayed signal;

S122. Superimpose the signal processed by synchronous superposition with the delayed signal to generate phase cancellation.

In the prior art, digital filters are classified into two categories: IIR and FIR. Among them, the FIR filter can obtain a strict linear phase, but its transfer function pole is fixed at the origin, and the performance can only be changed by changing the zero position, and its order is relatively high. The IIR filter has feedback, and the pole can be designed, so that the filtering can be completed more efficiently. The present invention finds through experiments that under the same design index, the order of the FIR filter is 5-10 times that of the IIR filter, so the embodiment of the present invention adopts the IIR digital comb filter.

In one embodiment of the present invention, the harmonic comb filter is represented by the following difference equation in the time domain:

Z-transform the equation, and its expression in the frequency domain is as follows:

The expression of the harmonic comb filter in the frequency domain is as follows:

Another expression in the frequency domain is as follows:

In the formula, z _k and z _j are the zero and pole points of the transfer function respectively, and the digital filter can be designed more intuitively by using the expression in the frequency domain.

The digital comb filter of the present invention solves the K-th harmonic of 50 Hz, but still causes damage to the signal in the passband. In order to solve this problem, preferably, a pole is added in the unit circle of each zero point , the frequency response of the comb filter consists of a series of regularly distributed peaks, enabling the comb filter to superimpose a signal with its delayed signal, resulting in phase cancellation.

Preferably, the comb filter in the discrete-time system satisfies the following formula:

In one embodiment of the present invention, the comb filter processing is realized by FPGA, including:

Use an FPGA with a multiply-adder to implement comb-filtering of the signal. Preferably, a plurality of FPGA cascades with multiplier-adders are provided for realization. The implementation method is as follows:

1) Let the signal sampling rate be fs, and the fundamental frequency of the frequency to be filtered out is fo, then:

fs=fo*D

2) The amplitude attenuation rate of the above filter to the signal is about 30dB.

In the receiver acquisition system, there are continuous 24kHz and the 2.4kHz data stream obtained by down-conversion sampling of the data stream. Considering that the fundamental frequency of the signal to be filtered is 50Hz, the embodiment of the present invention filters the 24kHz data stream. Order D=96, D=48 for 2.4kHz data stream.

Since the signal attenuation rate of one set of filters is 30dB, it cannot meet the requirements of signal filtering in actual collection, the present invention designs two sets of filter cascades:

Using the above filter, the signal attenuation rate is about 60dB.

To implement the above comb filter in the 24kHz and 2.4kHz data streams, the required filter orders are 192 and 96 respectively. It is generally difficult to implement a 192-order filter with the remaining resources of the FPGA chip in the system circuit, so the embodiment of the present invention filters the 2.4kHz data stream.

In the embodiment of the present invention, the FPGA needs a multiply-adder and a set of data buffers to implement the filter. The CLK of the multiplier-adder is connected to the overall clock of the system.

Considering that in practical application, the RAM resource of FPGA is tight, so in the embodiment of the present invention, in order to save the RAM resource inside FPGA, use register to do cache area, namely two-dimensional register array, cache is realized by the shift operation of register .

In the calculation process of the comb filter, it is carried out channel by channel. Due to the design of the previous data generation link, the time interval between adjacent channel data generation needs to be sufficient to complete the calculation. The calculation of each channel is controlled by a group of state machines, and the state machine has 8 states, and the state change relationship is shown in FIG. 4 .

The comb filter of the present invention also includes, in order to complete the operation at one time, improve the calculation speed, preferably use a plurality of multiplier-adder cascades, more preferably 5, so that the calculation of Fig. 4 can be completed at one time, and the calculation speed can be improved. Calculate speed.

The comb filter of the present invention also includes that in order to further improve the attenuation rate of the stop band and meet the use requirements under more complex conditions, the present invention preferably uses on-chip RAM as a data buffer area, and allows multiple comb filters cascaded to increase its order.

After completing the comb filter processing of S120, considering that the frequency-domain electromagnetic method signal is greatly disturbed by spike noise, the present invention analyzes and studies common spike noise, including atmospheric noise interference, such as spark discharge generated by lightning, which belongs to pulse broadband interference , whose coverage frequency ranges from 1 Hz to more than 100 MHz; solar noise interference (that is, the radiation noise of sunspots), during the active period of sunspots, the explosion of sunspots produces strong noise thousands of times higher than that of the stable period; industrial equipment noise interference, such as induction Interference caused by heating equipment, high-frequency electric welding machines, etc.; electrical equipment noise interference, including electromagnetic interference caused by drastic current changes caused by switching on and off of servo motors, electric drills, and relays; broadband noise interference generated by ignition systems of automobiles and internal combustion engines. The present invention classifies common peak noise interference in the frequency domain electromagnetic method into pulse-type stray current noise, and simulates it into three types: rectangular pulse, half-sine pulse and triangular pulse.

The present invention finds through research that the peak pulse mainly affects low-frequency electromagnetic signals. The larger the pulse amplitude, the greater the impact on low-frequency signals, and at the same time increase the impact on high-frequency signals; the smaller the pulse amplitude, the smaller the impact on low-frequency signals, while the impact on high-frequency signals is reduced, or even negligible. When the pulse width becomes wider, it has a greater impact on low-frequency signals and also has a greater impact on high-frequency signals; when the pulse width becomes narrower, the range of influence extends to high-frequency signals. Therefore, through the time-domain and frequency-domain mathematical model analysis of the above-mentioned peak noise, the embodiment of the present invention uses the α-trimmed filtering method to process the data collected by the frequency-domain electromagnetic method.

In the embodiment of the present invention, step S130 performs α-Trimed filtering on the comb-filtered signal, including:

S131, setting the window length N and parameter α, wherein α represents the percentage of the trimmed data sample;

S132. Process the signal according to the window length N and the parameter α. The processing steps include: filtering out redundant data according to the window length N and the parameter α; performing averaging processing on the remaining data.

S133, move the window by one element, and process the signal.

Optionally, before the signal is processed, the method further includes: acquiring a value corresponding to the signal; adding additional signals to the signal head and the signal tail respectively, preferably, the added additional signals are symmetrical addition; The values corresponding to the above signals are sorted from small to large.

Optionally, adding additional signals at the signal header and the signal tail respectively includes: if the window length N is an even number, adding N/2 data at the signal header and the signal tail respectively; if the window length N is If the number is odd, add (N-1)/2 data to the signal head and signal tail respectively.

The α-trimmed mean value filter adopted in the embodiment of the present invention has a dynamic filter characteristic, and the value of any element of the signal depends on the value around the element. Select a window of a certain size to remove heterogeneous elements (values at both ends after the data values are sorted from small to large), and use the remaining elements to calculate the average value to obtain the filtering result. Choose a window length N, according to the correlation between adjacent signals, produce a filter with the target effect. The number of removed heterogeneous elements depends on the parameter α (α represents the percentage of trimmed data samples), and 0≤α≤0.5. Assume that the data set {X(j)} with a window length of N is reordered, that is, {X(1)≤X(2)≤...≤X(i)≤...≤X(N-1)≤X(N) }. The output of the α-trimmed mean filter is shown in the following formula:

Among them, [αN] represents the lower integer function. When α=0, Xα needs to use all the sample values in the window for average calculation, and Xα behaves as a mean filter; when α=0.5, Xα is equal to the intermediate sample value after the window is reordered (N is an odd number at this time ), Xα behaves as a median filter. If N is an even number, and when α=0.5, the median Xα is equal to the average value of the middle two samples.

Taking an odd number of window length N as an example to illustrate α-trimmed mean filtering. Assuming that the selected filter window length N is 5, and α=0.2, then two elements (X1, X5) in the data are eliminated. Due to the symmetry of the way the filter removes elements, the number of removed elements must be an even number and less than the window length N. In actual operation, the window value N>1, so when using the α-trimmed mean filter, several elements at the beginning and end of the signal sequence cannot be selected to meet the window size elements. The method adopted by the present invention is: before using the filtering operation, add an additional signal whose length is about half of the window size at the beginning and end of the signal, and add symmetrically with the beginning and the end as axis elements.

In the case of a one-dimensional signal, as shown in Figure 5, when the window length N is an even number, in order to ensure that all original data are filtered once, N/2 elements are added to the head and tail of the original data; when the window length N When it is an odd number, (N-1)/2 elements are added to the head and tail of the original data.

In the case of two-dimensional signals, the signal processing method is basically the same as that of one-dimensional signals, except that the window selection of the α-trimmed mean filter becomes two-dimensional, usually a 3×3 matrix. As shown in Figure 6, the way to extend the two-dimensional data is to add some axes around the original data, and then add symmetrical elements in a one-dimensional way.

No matter the frequency domain electromagnetic method of MT mode or CSAMT mode collects data, it is mainly narrow pulse interference, so it is necessary to increase the window length appropriately, preferably, N=10. According to the characteristics of the data, the appropriate window length N and the filtering parameter α are selected, and the data filtering effect is better.

The α-Trimed in the embodiment of the present invention can be realized by FPGA, and the present invention uses the combination of STM32 embedded MCU chip and XILINX Spartan6FPGA as the core main control board processing unit of the frequency domain electromagnetic method receiver. Based on the Verilog language, the α-trimmed filtering method is transplanted into the FPGA chip program. FIG. 7 is a schematic flow diagram of the α-trimmed filter filtering according to an embodiment of the present invention, and the flow includes:

Step 710, input raw data;

Step 720, extend the data;

Step 730, setting the window length;

Step 740, data sorting;

Step 750, removing abnormal data;

Step 760, averaging the remaining data;

Step 770, generate new data;

Step 780, judge whether the data processing is completed, if so, go to step 720, if not, then go to step 790;

Step 790, the filtering is completed.

Further, the anti-jamming method for the multi-channel receiver according to the present invention also includes:

Collect the original signal and convert it into a voltage signal through the readout circuit;

converting the voltage signal into a digital signal by an analog-to-digital converter;

The digital signal is transmitted to the FPGA data buffer area through the data bus;

Then extract the signal from the FPGA data buffer area for superimposed filtering processing,

In order to reduce quantization noise, preferably, the analog-to-digital converter is a high-speed 24-bit analog-to-digital converter.

Further, the anti-interference method for a multi-channel receiver according to the present invention, after performing step S130 to perform α-Trimed filtering on the comb-filtered signal, further includes:

Carrying out DFT operation on the data after the α-Trimed filter processing;

Save the data to the storage device and transmit it to the monitoring device at the same time;

Monitor data quality in real time through monitoring equipment.

Through the real-time storage and monitoring of read data, when a problem is found, the relevant data of this period can be retrieved in time for analysis and elimination, which can further eliminate interference, increase data quality, and improve the performance of multi-channel receivers.

An embodiment of the present invention also provides an anti-jamming system for a multi-channel receiver, the system comprising:

Synchronous superposition filter, which performs synchronous superposition processing on the original signal received by the multi-channel receiver;

Comb filter, performing comb filter processing on the signal after synchronous superposition processing;

an α-Trimed filter, performing α-Trimed filter processing on the signal processed by the comb filter.

The anti-jamming method and system of the multi-channel receiver described in the embodiment of the present invention can filter out various kinds of interference in the signal by introducing three kinds of filtering techniques, realize the acquisition and processing of wide-band weak signals, and improve the electrical method. Accuracy of prospecting methods and electrical prospecting instruments.

While preferred embodiments of the invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, it is intended that the appended claims be construed to cover the preferred embodiment as well as all changes and modifications which fall within the scope of the invention.

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 equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (10)

1. a kind of anti-interference method for multi-channel receiver, which is characterized in that the described method includes:

Superposition processing is synchronized to multi-channel receiver received signal；

Comb filtering processing is carried out to the signal after the synchronized superposition processing；

α-Trimed filtering processing is carried out to the signal after comb filtering is processed.

2. the method as described in claim 1, which is characterized in that it is described multi-channel receiver received signal is synchronized it is folded Add processing, comprising:

Multi-channel receiver received signal is divided into multiple signal segments；

Signal in each signal segment is divided into multiple signal sections；

Multiple signal sections in each signal segment are overlapped, each respective amplitude of signal segment is obtained and phase is believed Breath；

Multiple superimposed signal segments are overlapped, the amplitude and phase information of the multichannel received signal are obtained.

3. method as described in claim 1, which is characterized in that carry out pectination filter to the signal after the synchronized superposition processing Wave processing, comprising:

It is delayed to multi-channel receiver received signal, becomes time delayed signal；

The multi-channel receiver received signal is superimposed with the time delayed signal, to generate phase cancellation.

4. method as claimed in claim 3, which is characterized in that carry out pectination to the signal after the synchronized superposition processing Filtering processing, comprising:

It is realized using the field programmable gate array (FPGA) with adder and multiplier to the letter after the synchronized superposition processing Number carry out comb filtering processing.

5. method as claimed in claim 4, which is characterized in that carry out pectination to the signal after the synchronized superposition processing Filtering processing, comprising:

Pectination is carried out to the signal after the synchronized superposition processing to realize using multiple FPGA cascades with adder and multiplier Filtering processing.

6. the method as described in claim 1, which is characterized in that carry out α-Trimed to the signal handled through comb filtering Filtering processing, comprising:

Length of window N and parameter alpha are set, and wherein α indicates the percentage for being trimmed data sample；

According to length of window N and parameter alpha, the signal handled through comb filtering is handled；

It is handled by the mobile element of window, then to the signal handled through comb filtering.

7. method as claimed in claim 6, which is characterized in that it is described according to length of window N and parameter alpha, to described through pectination The signal of filtering processing is handled, comprising:

According to length of window N and parameter alpha, redundant data is filtered out；

Average treatment is done to remaining data.

8. the method for claim 7, which is characterized in that carry out α-Trimed to the signal handled through comb filtering Before filtering processing, further includes:

Obtain the corresponding numerical value of multi-channel receiver received signal；

Additional signal is added respectively in signal heads and signal tail, and the additional signal added is symmetrical addition；

To the corresponding numerical value of the multi-channel receiver received signal according to sorting from small to large.

9. method according to claim 8, which is characterized in that additional signal is added respectively in the signal heads and signal tail, Include:

If the length of window N is even number, N/2 data are respectively added in signal heads and signal tail；

If the length of window N is odd number, (N-1)/2 data are respectively added in signal heads and signal tail.

10. a kind of jamproof system for multi-channel receiver, which is characterized in that the system comprises:

Synchronous superposition filter, for synchronizing superposition processing to multi-channel receiver received signal；

Comb filter, for carrying out comb filtering processing to the signal after the synchronized superposition processing；

α-Trimed filter, for carrying out α-Trimed filtering processing to the signal handled through comb filtering.