CN115622581B - Frequency domain anti-interference method for non-cooperative communication signals under non-ideal channel - Google Patents
Frequency domain anti-interference method for non-cooperative communication signals under non-ideal channel Download PDFInfo
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
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Abstract
The invention provides a frequency domain anti-interference method of non-cooperative communication signals under a non-ideal channel, which comprises the following steps: carrying out actual signal power spectrum estimation on a current input signal to obtain a signal actual measurement power spectral density curve; selecting a spectral line of any frequency point in a signal actual measurement power spectrum curve, calculating the average value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidth on the left and right sides of the spectral line of the frequency point, and taking the average value as the signal reference power spectral density of the frequency point; and calculating the difference value between the actually measured power spectral density and the reference power spectral density of the frequency point, taking the difference value as an interference detection decision quantity, and performing interference decision and inhibition on the interference detection decision quantity and the selected fixed threshold. The invention solves the technical problem that the interference threshold is difficult to design based on the theoretical frequency spectrum of the signal under the condition that the frequency spectrum of the communication signal is unknown and changeable in the non-cooperative communication signal interception process in the prior art.
Description
Technical Field
The invention relates to the technical field of communication signal demodulation and detection terminals, in particular to a frequency domain anti-interference method for non-cooperative communication signals under non-ideal channels.
Background
In a communication signal demodulation and detection system, various single-frequency/narrow-band interference signals cause problems such as signal-to-noise ratio reduction and bit error rate improvement of the signals, and in order to overcome the problems, anti-interference processing is generally required. The conventional narrowband interference suppression processing method is generally performed in a time domain or a frequency domain. The time domain anti-interference needs iterative estimation of anti-interference weight, the convergence speed is low, and generally only stable narrow-band interference can be processed, while the frequency domain anti-interference technology filters interference signals in a frequency domain notch and can suppress time-varying interference signals.
One of the most important links of the frequency domain interference rejection process is to determine an interference threshold. In the fields of satellite navigation and the like, because the landing level of a navigation signal is low and is far lower than noise, the signal spectrum is a flat noise spectrum, the threshold of the navigation signal can be directly determined by taking the mean value of the noise spectrum as reference, and the threshold can be determined in a self-adaptive manner by adopting a conventional self-adaptive threshold method. The intensity of the communication signal is higher than that of the noise bottom, the mean value of the signal frequency spectrum cannot be simply taken as the reference for threshold design, the frequency spectrum of an ideal communication signal usually has a symmetrical characteristic, at the moment, the signal cancellation can be realized by subtracting the positive frequency spectrum and the negative frequency spectrum, then the noise spectrum containing interference is obtained, and the mean value of the frequency spectrum can be directly taken as the reference for threshold design. After an actual communication signal passes through a non-ideal transceiving channel and a fading channel, the frequency spectrum of the actual communication signal is often distorted, the shape of the frequency spectrum of the actual communication signal is unknown, and for the field of non-cooperative communication signal detection and reception, the frequency spectrum of the actual communication signal is unknown and variable, so that the interference threshold is difficult to design based on the theoretical frequency spectrum of the actual communication signal.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a frequency domain anti-interference method for non-cooperative communication signals under a non-ideal channel, which can realize signal demodulation and anti-interference reception of a detection terminal under the scene that the communication signal frequency spectrum is unknown under the non-ideal communication channel and the non-cooperative communication, and solves the technical problem that the interference threshold is difficult to design based on the theoretical frequency spectrum of the signals under the conditions that the signal frequency spectrum is distorted and unknown in shape after the communication signals pass through a non-ideal transceiving channel and a fading channel and under the condition that the communication signal frequency spectrum is unknown and changeable in the non-cooperative communication signal detection and reception process in the prior art.
The technical scheme of the invention is as follows:
a frequency domain anti-jamming method for non-cooperative communication signals under non-ideal channels comprises the following steps:
carrying out actual signal power spectrum estimation on a current input signal to obtain a signal actual measurement power spectral density curve;
selecting a spectral line of any frequency point in a signal actual measurement power spectral curve, calculating the average value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidth on the left side and the right side of the spectral line of the frequency point, and taking the average value as the signal reference power spectral density of the frequency point;
and calculating the difference value between the actually measured power spectral density and the reference power spectral density of the frequency point, taking the difference value as an interference detection decision quantity, and performing interference decision and inhibition on the interference detection decision quantity and the selected fixed threshold.
Further, the actual signal power spectrum estimation is performed on the current input signal to obtain a signal actually-measured power spectral density curve, and the method specifically includes:
acquiring a section of data block in a current input signal, calculating the power spectral density of the data block, and acquiring a first signal actual measurement power spectral density curve, wherein the data block comprises N points of data;
selecting N/2 point data of the data block, combining the data block with the next section of data block in the acquired current input signal to form an overlapped data block, calculating the power spectral density of the overlapped data block, and acquiring a first signal actual measurement power spectral density curve, wherein the number of the data points of the next section of data block is N/2;
and calculating the actually measured first signal power spectral density curve of the continuous K sections of overlapped data blocks according to the method, then averaging the actually measured first signal power spectral density curve and taking the logarithm of the actually measured first signal power spectral density curve to obtain the actually measured second signal power spectral density curve.
Further, obtaining the measured power spectral density curve of the first signal specifically includes:
performing fast Fourier transform on a current input signal, multiplying the current input signal by signal phase information, summing the products, and then squaring an absolute value to obtain a first signal actual measurement power spectral density curve of each section of data block; measured power spectral density curve P of first signal 0 [k,n]The expression of (a) is:
(1) Where x (i) is the current input signal, e -j2πni The value range of the phase information of the current input signal is 0, K, N is the serial number of the spectral line of the power spectrum, i is the serial number of the sampling point of the signal, N is the number of the data points of the power spectrum estimation, k is the segment serial number of the data block or the overlapped data block]And K is the number of segments of consecutive overlapping data blocks.
Further, the method includes the steps of calculating a first signal measured power spectral density curve of the continuous K-segment overlapped data blocks according to the method, averaging the first signal measured power spectral density curve and taking a logarithm of the average to obtain a second signal measured power spectral density curve, and specifically includes the steps of:
acquiring first signal actual measurement power spectral density values of continuous K sections of overlapped data blocks, averaging the plurality of first signal actual measurement power spectral density values, and finally, taking a logarithm of the average value to obtain a second signal actual measurement power spectral density curve; the expression of the measured power spectral density curve P [ n ] of the second signal is as follows:
(2) In the formula, P 0 [k，n]And (3) a measured power spectral density curve of the second signal is obtained, a variable K is the serial number of the overlapped data blocks, n is the serial number of the power spectral line, and K is the number of the overlapped data blocks.
Further, calculating the mean value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidth on the left side and the right side of the frequency point spectral line, specifically including:
according to the spectral line of any frequency point in the selected second signal actual measurement power spectral line curve, selecting a signal frequency spectral line outside the maximum narrowband interference bandwidth on the left side of the second signal spectral line, marking the serial number of the signal frequency spectral line, calculating the power spectral density of the signal frequency spectral line outside the maximum narrowband interference bandwidth on the left side, and marking as the third signal actual measurement power spectral line density, wherein the serial number of the spectral line of the third signal actual measurement power spectral line density is the remainder of the difference between the serial number of the spectral line of any frequency point and the number of spectral lines under the maximum interference bandwidth divided by the number of data points estimated by the actual measurement power spectrum;
selecting a signal spectrum line outside the maximum narrowband interference bandwidth on the right side of the signal spectrum line, marking the serial number of the signal spectrum line, calculating the power spectral density of the signal spectrum line outside the maximum narrowband interference bandwidth on the right side, and marking as the actually measured power spectral density of a fourth signal, wherein the serial number of the spectrum line of the actually measured power spectral density of the fourth signal is the remainder of the sum of the serial number of the spectrum line of any one frequency point and the number of the spectrum lines under the maximum interference bandwidth divided by the number of data points estimated by the actually measured power spectrum;
obtaining a signal reference power spectral density P corresponding to the second signal actual measurement power spectral density curve through a value obtained by dividing the sum of the third signal actual measurement power spectral density and the fourth signal actual measurement power spectral density by the number of spectral lines under twice of the maximum bandwidth, namely the mean value of two sections of signal frequency spectrums outside the left and right maximum narrow-band interference bandwidths ref [n]The expression is as follows:
(3) In the formula, P ref [n]For signal reference power spectral density, P [ (N-N) f -i)％N]Measuring a power spectral density, P [ (N + N), for the third signal f +i)％N]Actually measuring the power spectral density of the fourth signal, wherein N is the serial number of the power spectral line of the power spectral estimation, and N f And i is the number of spectral lines under the maximum interference bandwidth, i is the serial number of the spectral lines under the maximum interference bandwidth, and N is the number of data points of power spectrum estimation.
Further, before calculating the mean value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidth on the left and right sides of the frequency point spectral line, the method further includes:
setting the maximum interference bandwidth required to be suppressed by narrow-band interference resistance as B j ；
Calculating the number of spectral lines under the maximum interference bandwidth, wherein the number of spectral lines under the maximum interference bandwidth is equal to the absolute value of the number of data points estimated by the power spectrum multiplied by the maximum interference bandwidth and divided by the signal sampling rate, and the expression is
N f ＝|B j /df|＝|NB j /f s | (4)
(4) In the formula, N f For the number of spectral lines under the maximum bandwidth of interference, N is workNumber of data points of rate spectrum estimation, f s For the signal sampling rate of the input signal, df is the frequency interval of the power spectral line when the number of data points of the power spectral estimation is N.
Further, calculating a difference between the actually measured power spectral density of the frequency point and the reference power spectral density, taking the difference as an interference detection decision quantity, and performing interference decision and suppression with a selected fixed threshold, specifically comprising:
taking a value of a fixed multiple of a difference value between the power spectral density of the frequency point and the reference power spectral density as an interference decision threshold value;
searching any spectral line in the first signal actual measurement power spectral density curve, judging whether the power spectral density value of the spectral line is larger than an interference judgment threshold value, and if so, marking the spectral line as a first interference spectral line;
searching spectral lines in a second signal actual measurement power spectral density curve corresponding to the first interference spectral line, marking the spectral lines as second interference spectral lines and deleting the second interference spectral lines;
and carrying out inverse fast Fourier transform on the actually measured power spectral density curve of the second signal to obtain an anti-interference result of the data block.
According to the invention, by utilizing the characteristic that the shape of the frequency spectrum of the communication signal is relatively smooth, for any frequency point spectral line in a second actually-measured power spectral density curve, the average value of two sections of signal frequency spectrums outside the left and right maximum narrow-band interference bandwidth is taken as the signal reference power spectrum of the frequency point, the difference value of the second actually-measured power spectral density and the reference power spectral density of the frequency point is the interference detection judgment amount, and a proper fixed threshold is selected for interference judgment and inhibition, so that under the scene that the frequency spectrum of the communication signal is unknown under the non-ideal communication channel and the non-cooperative communication, the signal demodulation and the anti-interference receiving of a detection terminal are realized.
The invention has the beneficial effects that:
1. according to the method, the average value of the actually measured power spectral density curves of the plurality of first signals is obtained, and the logarithm of the average value is finally obtained, so that the actually measured power spectral density curve of the second signal with higher precision is obtained, and the precision of the interference detection judgment quantity is improved;
2. under the scene that the communication signal frequency spectrum is unknown under non-ideal communication channels and non-cooperative communication, the anti-interference receiving of a signal demodulation and detection terminal is realized, and the technical problem that in the prior art, after the communication signal passes through a non-ideal transceiving channel and a fading channel, the signal frequency spectrum is distorted and unknown in shape, and in the process of detecting and receiving the non-cooperative communication signal, the interference threshold is difficult to design based on the theoretical frequency spectrum of the signal under the condition that the communication signal frequency spectrum is unknown and variable is solved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. In the drawings:
fig. 1 is a flowchart of a frequency domain interference rejection method for non-cooperative communication signals in a non-ideal channel according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for calculating a measured power spectral density curve of a second signal according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for calculating a signal reference power spectral density curve according to an embodiment of the present invention;
fig. 4 is a flowchart of an interference detection suppression processing method according to an embodiment of the present invention.
Detailed Description
Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.
As shown in fig. 1, a frequency domain anti-interference method for non-cooperative communication signals in a non-ideal channel includes the following steps:
s01, estimating the power spectral density of an actual signal: estimating the power spectrum of the actual signal of the current input signal to obtain a first signal actual measurement power spectrum density curve and a second signal actual measurement power spectrum density curve;
s02, calculating signal reference power spectral density: calculating the number of spectral lines under the maximum interference bandwidth, selecting the spectral line of any frequency point in a signal actual measurement power spectral curve, calculating the average value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidths on the left side and the right side of the spectral line of the frequency point, and taking the average value as the signal reference power spectral density of the frequency point;
s03, interference detection and suppression processing: and calculating the difference value between the actually measured power spectral density and the reference power spectral density of the frequency point, taking the difference value as an interference detection decision quantity, and performing interference decision and inhibition on the interference detection decision quantity and the selected fixed threshold.
In the step of estimating the power spectrum of the actual signal, the step of estimating the power spectrum of the actual signal is performed on the current input signal to obtain a first signal actual measurement power spectral density curve and a second signal actual measurement power spectral density curve, as shown in fig. 2, which specifically includes:
s101, acquiring any section of data block in a current input signal, calculating power spectral density of the data block, and acquiring a first signal actual measurement power spectral density curve, wherein the data block comprises N points of data, and the any section of data block can be defined as a first section of data block;
s102, selecting N/2 point data of the data block, combining the data block with the next section of data block in the obtained current input signal to form an overlapped data block, calculating the power spectral density of the overlapped data block, and obtaining a first signal actual measurement power spectral density curve, wherein the number of the data points of the next section of data block is N/2;
s103, repeating the step S102, calculating and obtaining a first signal actual measurement power spectrum density curve of the continuous K sections of overlapped data blocks, then calculating an average of the first section of data block and the continuous K sections of overlapped data blocks and logarithm of the average to obtain a second signal actual measurement power spectrum density curve, wherein the second signal actual measurement power spectrum density curve has higher precision than the first signal actual measurement power spectrum density curve.
The above-mentioned manner of obtaining the first signal measured power spectral density curve of the first segment of data block in step S101 is the same as the above-mentioned manner of obtaining the first signal measured power spectral density curve of the overlapped data block in step S102, and the manner of obtaining the first signal measured power spectral density curve by calculation is as follows:
fast Fourier transform of current input signalMultiplying the current input signal by the signal phase information, summing the products, and then squaring an absolute value to obtain a first signal actual measurement power spectral density curve of each section of data block; measured power spectral density curve P of first signal 0 [k，n]The expression of (c) is:
(5) Where x (i) is the current input signal, e -j4πni N is the phase information of the current input signal, N is the serial number of the spectral line of the power spectrum, i is the serial number of the sampling point of the signal, N is the number of data points estimated by the power spectrum, k is the segment sequence number of the data block or the overlapped data block, and the value range is [0, K]And K is the data block or the total segment number of the data block.
In the step S103, the actually measured first signal power spectral density curve of the consecutive K segments of overlapped data blocks is obtained through calculation, then an average of the first segment of data block and the consecutive K segments of overlapped data blocks is obtained, and a logarithm of the average is obtained, so as to obtain an actually measured second signal power spectral density curve, which specifically includes:
acquiring a first signal actually-measured power spectral density value of a first segment of data block and continuous K segments of overlapped data blocks;
averaging the plurality of first signal actual measurement power spectrum density values, and finally, taking logarithm of the average value to obtain a second signal actual measurement power spectrum density curve; the expression of the measured power spectral density curve P [ n ] of the second signal is as follows:
(6) In the formula, P 0 [k，n]And (3) actually measuring a power spectral line curve for the second signal, wherein a variable K is the serial number of the overlapped data blocks, n is the serial number of the power spectral line, and K is the total number of the segments of the data blocks, namely the sum of the segments of the first segment of data block and the overlapped data block.
In the step of calculating the signal reference power spectrum, the number of spectral lines under the maximum interference bandwidth is calculated, and the average value of two sections of signal spectra outside the maximum narrowband interference bandwidths on the left and right sides of the frequency point spectral line is calculated, as shown in fig. 3, specifically including:
s201, calculating the number of spectral lines under the maximum interference bandwidth, wherein the number of spectral lines under the maximum interference bandwidth is equal to an absolute value obtained by multiplying the number of data points estimated by the power spectrum by the maximum interference bandwidth and dividing the multiplied data points by a signal sampling rate, and the expression is
N f ＝|B j /df|＝|NB j /f s | (7)
(7) In the formula, N f For the number of spectral lines under the maximum bandwidth of interference, N is the number of data points for power spectrum estimation, f s For the signal sampling rate of the input signal, df is the frequency interval of the power spectral line when the number of data points estimated by the power spectrum is N, and the maximum interference bandwidth required to be suppressed by narrow-band anti-interference is B j 。
S202, according to the spectral line of any frequency point in the selected second signal actual measurement power spectrum density curve, selecting a signal spectrum spectral line outside the maximum narrow-band interference bandwidth on the left side of the second signal actual measurement power spectrum density curve, marking the serial number of the signal spectrum spectral line, calculating the power spectrum density of the signal spectrum spectral line outside the maximum narrow-band interference bandwidth on the left side, and marking as the third signal actual measurement power spectrum density, wherein the serial number of the spectral line of the third signal actual measurement power spectrum density is the remainder of the difference value of the serial number of the spectral line of any frequency point and the number of spectral lines under the maximum interference bandwidth divided by the number of data points estimated by the actual measurement power spectrum;
s203, selecting a signal spectrum line outside the maximum narrow-band interference bandwidth on the right side of the signal spectrum line, marking the serial number of the signal spectrum line, calculating the power spectrum density of the signal spectrum line outside the maximum narrow-band interference bandwidth on the right side, and marking as a fourth signal actually-measured power spectrum density, wherein the serial number of the fourth signal actually-measured power spectrum density is a remainder of the sum of the serial number of the spectrum line of any one frequency point and the number of the spectrum lines under the maximum interference bandwidth divided by the number of data points estimated by the actually-measured power spectrum;
s204, dividing the sum of the third signal actual measurement power spectrum density and the fourth signal actual measurement power spectrum density by the number of spectral lines under twice of the maximum bandwidth to obtain a value, namely the left and right maximum narrow-band interferenceObtaining a signal reference power spectral density P corresponding to a second signal actually-measured power spectral density curve by averaging two sections of signal frequency spectrums outside the bandwidth ref [n]The expression is as follows:
(8) In the formula, P ref [n]For signal reference power spectral density, P [ (N-N) f -i)％N]Measuring the power spectral density, P [ (N + N) for the third signal f +i)％N]The measured power spectral density of the fourth signal is obtained, N is the serial number of the power spectral line of the power spectral estimation, N f The number of spectral lines under the maximum interference bandwidth is shown as i, the serial number of the spectral lines under the maximum interference bandwidth is shown as i, and the number of data points of power spectrum estimation is shown as N.
In the interference detection suppression processing step, the difference between the actually measured power spectral density of the frequency point and the reference power spectral density is calculated, the difference is used as the interference detection decision quantity, and the interference decision and suppression are carried out with the selected fixed threshold, which specifically comprises the following steps:
s301, taking a value of a fixed multiple of a difference value between the power spectral density of the frequency point and the reference power spectral density as an interference decision threshold value thr;
s302, spectral line searching is carried out from a first signal actual measurement power spectral line curve, whether the power spectral line value of the spectral line is larger than an interference judgment threshold value thr or not is judged, if yes, the spectral line is marked as a first interference spectral line, meanwhile, a subscript corresponding to the first interference spectral line is marked as m (L) (L is more than or equal to 0 and less than L), and L is the number of all spectral lines;
s303, searching spectral lines in the second signal actual measurement power spectral density curve corresponding to the first interference spectral line, namely searching spectral lines corresponding to the first interference spectral line in the second signal actual measurement power spectral density curve of the first data block and the continuous K overlapped data blocks, marking the searched spectral lines as second interference spectral lines and clearing, wherein the expression is P 0 [k，m(l)](0 is more than or equal to L and less than L) =0, wherein the variable k is the serial number of the overlapped data blocks, and m (L) (0 is more than or equal to L and less than L) is the label of the second interference spectral line, and the label is the same as the label of the first interference spectral line.
S304, after all the second interference spectral lines are cleared, actually measuring a power spectral density curve P of the second signal 0 [k，n]And (N is more than or equal to 0 and less than N), performing inverse fast Fourier transform, namely ifft transform, and obtaining anti-interference results of all the data blocks.
According to the embodiment of the invention, by utilizing the characteristic that the shape of the frequency spectrum of the communication signal is relatively smooth, the average value of two sections of signal frequency spectrums outside the left and right maximum narrow-band interference bandwidths of any frequency point spectral line in a second measured power spectrum density curve is taken as the signal reference power spectrum density of the frequency point, the difference value of the second measured power spectrum density and the reference power spectrum density of the frequency point is the interference detection judgment quantity, and a proper fixed threshold is selected for interference judgment and suppression, so that under the scene that the frequency spectrum of the communication signal is unknown under non-ideal communication channels and non-cooperative communication, the signal demodulation and the anti-interference reception of a detection terminal are realized, and the technical problem that the interference threshold is difficult to design based on the theoretical frequency spectrum of the signal under the conditions that the communication signal passes through the non-ideal transceiving channels and fades and the communication signal is unknown in the prior art and under the condition that the frequency spectrum of the communication signal is unknown and changeable in the non-cooperative communication signal detection process is solved.
Claims (7)
1. A frequency domain interference rejection method for non-cooperative communication signals in a non-ideal channel, the frequency domain interference rejection method comprising the steps of:
carrying out actual signal power spectrum estimation on a current input signal to obtain a signal actual measurement power spectral density curve;
selecting a spectral line of any frequency point in a signal actual measurement power spectral curve, calculating the average value of two sections of signal frequency spectrums outside the maximum narrow-band interference bandwidth on the left side and the right side of the spectral line of the frequency point, and taking the average value as the signal reference power spectral density of the frequency point;
and calculating the difference value between the actually measured power spectral density and the reference power spectral density of the frequency point, taking the difference value as an interference detection judgment quantity, and carrying out interference judgment and inhibition on the interference detection judgment quantity and the selected fixed threshold.
2. The method as claimed in claim 1, wherein the frequency-domain interference rejection method for the non-cooperative communication signal under the non-ideal channel comprises performing actual signal power spectrum estimation on the current input signal to obtain a signal actual measurement power spectral density curve, and specifically comprises:
acquiring a section of data block in a current input signal, calculating the power spectral density of the data block, and acquiring a first signal actual measurement power spectral density curve, wherein the data block comprises N points of data;
selecting N/2 point data of the data block, combining the data block with the next section of data block in the acquired current input signal to form an overlapped data block, calculating the power spectral density of the overlapped data block, and acquiring a first signal actual measurement power spectral density curve, wherein the number of the data points of the next section of data block is N/2;
and calculating the actually measured first signal power spectral density curve of the continuous K sections of overlapped data blocks according to the method, then averaging the actually measured first signal power spectral density curve and taking the logarithm of the actually measured first signal power spectral density curve to obtain the actually measured second signal power spectral density curve.
3. The method as claimed in claim 2, wherein the obtaining of the measured power spectral density curve of the first signal comprises:
performing fast Fourier transform on a current input signal, multiplying the current input signal by signal phase information, summing the products, and then squaring an absolute value to obtain a first signal actual measurement power spectrum density curve P of each data block, wherein the first signal actual measurement power spectrum density curve P is a curve of the first signal actual measurement power spectrum density 0 [k,n]Is expressed as
(1) Where x (i) is the current input signal, e -j2πni N is the phase information of the current input signal, N is the serial number of the spectral line of the power spectrum, i is the serial number of the sampling point of the signal, N is the number of data points estimated by the power spectrum, k is the segment serial number of the data block, and the value range is [0, K]And K is the number of segments of the data block.
4. The method of claim 2, wherein the interference rejection is performed in the frequency domain for non-cooperative communication signals in non-ideal channels,
calculating a first signal actual measurement power spectrum density curve of continuous K sections of overlapped data blocks according to the method, then averaging the curve and taking the logarithm to obtain a second signal actual measurement power spectrum density curve, and specifically comprising the following steps:
acquiring first signal actual measurement power spectrum density values of continuous K sections of overlapped data blocks, averaging the plurality of first signal actual measurement power spectrum density values, and finally, taking logarithm of the average value to obtain a second signal actual measurement power spectrum density curve; the expression of the measured power spectral density curve P [ n ] of the second signal is as follows:
(2) In the formula, P 0 [k,n]And (3) a measured power spectral density curve of the second signal is obtained, a variable K is the serial number of the overlapped data blocks, n is the serial number of the power spectral line, and K is the number of the overlapped data blocks.
5. The method according to claim 1, wherein calculating the mean of two signal spectra outside the maximum narrowband interference bandwidth on the left and right sides of the spectral line of the frequency point specifically comprises:
according to the spectral line of any frequency point in the selected second signal actual measurement power spectrum density curve, selecting a signal spectrum spectral line outside the maximum narrow-band interference bandwidth on the left side of the second signal actual measurement power spectrum density curve, marking the serial number of the signal spectrum spectral line, calculating the power spectrum density of the signal spectrum spectral line outside the maximum narrow-band interference bandwidth on the left side, and marking as the third signal actual measurement power spectrum density, wherein the serial number of the spectral line of the third signal actual measurement power spectrum density is the remainder of the difference between the serial number of the spectral line of any frequency point and the number of spectral lines under the maximum interference bandwidth divided by the number of data points estimated by the actual measurement power spectrum;
selecting a signal spectrum line outside the maximum narrowband interference bandwidth on the right side of the signal spectrum line, marking the serial number of the signal spectrum line, calculating the power spectral density of the signal spectrum line outside the maximum narrowband interference bandwidth on the right side, and marking as a fourth signal actual measurement power spectral density, wherein the serial number of the fourth signal actual measurement power spectral density is the remainder of the sum of the serial number of the spectrum line of any one frequency point and the number of the spectrum lines under the maximum interference bandwidth divided by the number of data points estimated by the actual measurement power spectrum;
obtaining a signal reference power spectral density P corresponding to the second signal measured power spectral density curve by dividing the sum of the third signal measured power spectral density and the fourth signal measured power spectral density by the number of spectral lines under twice the maximum bandwidth ref [n]The expression is as follows:
(3) In the formula, P ref [n]For signal reference power spectral density, P [ (N-N) f -i)％N]Measuring the power spectral density, P [ (N + N) for the third signal f +i)％N]The measured power spectral density of the fourth signal is obtained, N is the serial number of the power spectral line of the power spectral estimation, N f The number of spectral lines under the maximum interference bandwidth is shown as i, the serial number of the spectral lines under the maximum interference bandwidth is shown as i, and the number of data points of power spectrum estimation is shown as N.
6. The method as claimed in claim 1 or 5, wherein before calculating the average of two signal spectra outside the maximum narrowband interference bandwidth on the left and right sides of the spectral line of the frequency point, the method further comprises:
setting the maximum interference bandwidth required to be suppressed by narrow-band interference resistance as B j ；
Calculating the number of spectral lines under the maximum interference bandwidth, wherein the number of spectral lines under the maximum interference bandwidth is equal to the absolute value of the number of data points estimated by the power spectrum multiplied by the maximum interference bandwidth and divided by the signal sampling rate, and the expression is
N f ＝|B j /df|＝|NB j /f s | (4)
(4) In the formula, N f The number of spectral lines under the maximum interference bandwidth is N, the number of data points of power spectrum estimation is N, fs is the signal sampling rate of the input signal, and df is the frequency interval of the power spectral line when the number of data points of power spectrum estimation is N.
7. The method according to claim 1, wherein the method for resisting interference in the frequency domain of the non-cooperative communication signal in the non-ideal channel comprises the steps of calculating a difference between an actually measured power spectral density and a reference power spectral density of the frequency point, using the difference as an interference detection decision metric, and performing interference decision and suppression with a selected fixed threshold, specifically comprising:
taking a value of a fixed multiple of a difference value between the power spectral density of the frequency point and the reference power spectral density as an interference decision threshold value;
searching any spectral line in the first signal actual measurement power spectral density curve, judging whether the power spectral density value of the spectral line is larger than an interference judgment threshold value, and if so, marking the spectral line as a first interference spectral line;
searching spectral lines in a second signal actual measurement power spectral density curve corresponding to the first interference spectral line, marking the spectral lines as second interference spectral lines and deleting the second interference spectral lines;
and carrying out inverse fast Fourier transform on the actually measured power spectral density curve of the second signal to obtain an anti-interference result of the data block.
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