Multi-signal detection method and system based on multi-phase filtering and STFT

Abstract

The invention discloses a multi-signal detection method and system based on multi-phase filtering and STFT. The multi-signal detection method based on multi-phase filtering and STFT comprises the following steps: firstly, collecting a pulse signal; digital channelization processing is carried out on the multiple pulse signals; extraction speed reduction, orthogonal down-conversion and multi-phase filtering processing are carried out on the multiple pulse signals in sequence; and then short-time Fourier transform is carried out on the multiple pulse signals, time-frequency correlation is carried out on frequency points in a short-time Fourier spectrum by using saturated pulses so as to obtain PDW parameter information of center frequencies, pulse widths, bandwidths and arrival times of the multiple pulse signals, the sensitivity of signal detection is improved on the basis of low FPGA resource consumption, and the signal false alarm rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of signal detection, and in particular to a multi-signal detection method and system based on polyphase filtering and STFT. Background Art

[0002] In the electronic warfare system, radar reconnaissance equipment needs to obtain the PDW parameter information of the enemy radar signal to provide a basis for the development of countermeasures against the radar. In order to meet the existing electronic warfare requirements, its receiver needs to have high sensitivity, high resolution, large dynamic range and full probability coverage. At present, for radar pulse measurement technology, the signal can be detected by multiphase filtering or the short-time Fourier change can be used to measure the signal in the frequency domain. However, when the signal is detected only in the time domain, the signal detection under low signal-to-noise ratio has a high false alarm rate. When the signal is detected only in the frequency domain, the time domain resolution depends on the time domain step value of the short-time Fourier change of the signal, and the frequency domain resolution depends on the number of points of the short-time Fourier change. Obtaining higher frequency resolution and time domain resolution will result in higher FPGA resource consumption. Summary of the invention

[0003] The purpose of the present invention is to design a multi-signal detection method based on polyphase filtering and STFT in order to solve the above problems.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0005] The multi-signal detection method based on polyphase filtering and STFT includes:

[0006] Collect multiple pulse signals;

[0007] Performing digital channelization processing on the plurality of pulse signals: sequentially performing extraction and down-conversion, orthogonal down-conversion, and multi-phase filtering processing on the plurality of pulse signals;

[0008] The multiple pulse signals are subjected to short-time Fourier transform, and the frequency points in the short-time Fourier spectrum are time-frequency correlated using saturated pulses to obtain the PDW parameter information of the multiple pulse signals.

[0009] The present invention further proposes a multi-signal detection system based on polyphase filtering and STFT, wherein the multi-signal detection system based on polyphase filtering and STFT is used to implement the multi-signal detection method based on polyphase filtering and STFT, and the multi-signal detection system based on polyphase filtering and STFT comprises:

[0010] A signal collector, the signal collector is used to collect multiple pulse signals;

[0011] A digital channelization module, the digital channelization module is connected to the signal receiver, and the digital channelization module is used to perform digital channelization processing on the plurality of pulse signals;

[0012] A time-frequency association module, the time-frequency association module is connected to the digital channelization module, and the time-frequency association module is used to perform time-frequency association processing on the multiple pulse signals to output a PDW parameter signal.

[0013] The beneficial effects of the present invention are:

[0014] The multi-signal detection method based on polyphase filtering and STFT first collects pulse signals; then performs digital channelization processing on multiple pulse signals: extracts and reduces speed, orthogonally down-converts, and performs polyphase filtering processing on multiple pulse signals in turn; then, short-time Fourier transforms the multiple pulse signals, and uses saturated pulses to perform time-frequency correlation on the frequency points in the short-time Fourier spectrum to obtain the PDW parameter information of the center frequency, pulse width, bandwidth and arrival time of multiple pulse signals, thereby improving the sensitivity of signal detection and reducing the signal false alarm rate on the basis of low FPGA resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of a multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0016] Figure 2 It is a schematic diagram of an even-type arrangement of a multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0017] Figure 3 This is an efficient structural diagram of complex signal channelization of a multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0018] Figure 4 A simple schematic diagram of STFT of a multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0019] Figure 5 It is a STFT operation flow chart of the multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0020] Figure 6 It is a schematic diagram of the time-frequency correlation process of the multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0021] Figure 7 It is a flow chart of the multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0022] Figure 8 A multi-phase filtering diagram of a multi-signal detection method based on multi-phase filtering and STFT of the present invention;

[0023] Fig. 9 It is a time-frequency diagram of the multi-signal detection method based on polyphase filtering and STFT of the present invention;

[0024] Fig.10 It is a multi-phase filtering detection envelope diagram of the multi-signal detection method based on multi-phase filtering and STFT of the present invention;

[0025] Fig.11 This is a PDW generation table for the multi-signal detection method based on polyphase filtering and STFT of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0030] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0033] like Figure 1-11 As shown, the multi-signal detection method based on polyphase filtering and STFT includes:

[0034] Collect multiple pulse signals;

[0035] Performing digital channelization processing on the plurality of pulse signals: sequentially performing extraction and down-conversion, orthogonal down-conversion, and multi-phase filtering processing on the plurality of pulse signals;

[0036] The multiple pulse signals are subjected to short-time Fourier transform, and the frequency points in the short-time Fourier spectrum are time-frequency correlated using saturated pulses to obtain the PDW parameter information of the multiple pulse signals.

[0037] In one embodiment, the PDW parameter information includes center frequency, pulse width, bandwidth and arrival time parameter information.

[0038] In this embodiment, a pulse signal is collected by a signal collector, and the pulse signal is real signal data information; then a plurality of pulse signals are digitally channelized by a digital channelization module. Specifically, the sampling rate is reduced to reduce the sampling rate of the pulse signal, thereby improving the signal detection sensitivity. In the present invention, a complex channelization even arrangement is used to obtain complex signal data information. Assuming that the input signal is s(n), the impulse response of the low-pass filter is h(n), the number of channels is K, the decimation rate is D, and the bandwidth of the channelization filter is 2π / K. When the decimation rate D=K is the critical decimation, w in the even arrangement channelization efficient structure is k =2πk / K, the channelization formula in the even arrangement is derived as ,in , w k =2πk / K Substituting this into the equation, we get , , and then perform multi-phase filtering on multiple pulse signals to calculate the modulus value of the pulse signal, then detect the saturated pulse information in the pulse signal and gate it; finally, perform STFT (short-time Fourier transform) on the gated output pulse signal, use the saturated pulse to detect the frequency points in the short-time Fourier spectrum, and perform time-frequency correlation on the detected frequency points to obtain the PDW parameter information of multiple pulse signals: center frequency (Fc), pulse width (PW), bandwidth (BW), arrival time (TOA) parameter information, the signal time domain resolution is the short-time Fourier step value, and the pulse signal is detected simultaneously in the time domain and frequency domain to reduce the signal false alarm rate and reduce the resource consumption of FPGA.

[0039] In this embodiment, the short-time Fourier transform is to add a window function to the pulse signal, that is, to perform Fourier transform on a pulse signal with a short time interval; the window function is translated on the entire time axis as the time t changes, thereby obtaining the frequency domain relationship of the pulse signal in a short time near any position; x(t) represents the input signal, w(t) represents the impulse response of the window function, and the short-time Fourier transform expression is: Signal analysis usually adopts discrete form. Assume that the discrete time series of the input signal is x(n), the impulse response of the window function is w(n), and its length is N. The translation of the window function on the time axis is equivalent to the translation of the signal on the time axis. The mathematical operation flow structure is expressed as follows: Figure 5 .

[0040] This embodiment collects pulse signals with a sampling rate of 5G. First, AD acquisition is performed on the pulse signal. The input signal frequency is 3G, the signal bandwidth is 20M, the signal pulse width is 2us, the repetition period is 20us, and the CPI is 1ms. The multi-phase filter simulation is as follows: Figure 8 , the time-frequency diagram is as follows Fig. 9 , the polyphase filter detection envelope diagram is as follows Fig.10 , PDW generates a table such as Fig.11 Its frequency measurement accuracy is <1Mz, and its time domain resolution is <0.05us. It can perform instantaneous measurements on multiple targets. The time domain measurement depends on the frequency domain measurement to improve the signal-to-noise ratio.

[0041] In the multi-signal detection method based on polyphase filtering and STFT of the present invention, pulse signals are firstly collected; then multiple pulse signals are subjected to digital channelization processing: multiple pulse signals are subjected to extraction and speed reduction, orthogonal down-conversion, and polyphase filtering processing in sequence; then, multiple pulse signals are subjected to short-time Fourier transform, and frequency points in the short-time Fourier spectrum are subjected to time-frequency correlation by using saturated pulses to obtain PDW parameter information of center frequency, pulse width, bandwidth and arrival time of multiple pulse signals, thereby improving the sensitivity of signal detection and reducing the signal false alarm rate on the basis of low FPGA resource consumption.

[0042] In one embodiment, the steps of the time-frequency association algorithm are specifically as follows:

[0043] Set up the time-frequency library;

[0044] Get the signal frequency within a short period of time;

[0045] Determine whether the signal frequency matches the signal frequency in the time-frequency library, if so, update the PDW parameter information of the signal frequency, otherwise, output the PDW parameter information.

[0046] In this embodiment, the time-frequency correlation algorithm uses the combination of time and frequency to calculate the signal pulse width and bandwidth. The basic algorithm flow is as follows: Figure 6 As shown, the signal frequency is obtained by using short-time Fourier change. Specifically, a time-frequency library is set first; then the signal frequency in a short period of time is obtained by using STFT, and it is determined whether the current signal frequency matches the signal frequency band in the time-frequency library. If it matches the signal frequency in the time-frequency library, the center frequency, bandwidth and pulse width of the signal frequency are updated; if it cannot match the signal frequency in the time-frequency library, the PDW parameter information of the current signal frequency is output: frequency (Fc), pulse width (PW), bandwidth (BW), and arrival time (Toa) information; finally, the time-frequency library is updated.

[0047] The present invention also proposes a multi-signal detection system based on multi-phase filtering and STFT, which is used to implement the above-mentioned multi-signal detection method based on multi-phase filtering and STFT; the specific detection method of the multi-signal detection system based on multi-phase filtering and STFT refers to the above-mentioned embodiment. Since the multi-signal detection system based on multi-phase filtering and STFT adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0048] In one embodiment, the multi-signal detection system based on polyphase filtering and STFT includes:

[0049] A signal collector, the signal collector is used to collect multiple pulse signals;

[0050] A digital channelization module, the digital channelization module is connected to the signal receiver, and the digital channelization module is used to perform digital channelization processing on the plurality of pulse signals;

[0051] A time-frequency association module, the time-frequency association module is connected to the digital channelization module, and the time-frequency association module is used to perform time-frequency association processing on the multiple pulse signals to output a PDW parameter signal.

[0052] In one embodiment, the digital channelization module comprises a decimator, a digital down converter and a polyphase filter, and the digital down converter is connected to the decimator and the polyphase filter respectively.

[0053] In this embodiment, the signal collector can be implemented by an AD integrated circuit to collect multiple pulse signals, which are real signal data information; then the multiple pulse signals are digitally channelized through a digital channelization module, and the digital channelization module can be implemented by a digital down-converter and a multi-phase filter. Specifically, the extractor extracts and reduces the speed of the pulse signal to reduce the sampling rate of the pulse signal, and obtains complex signal data information at the same time, thereby improving the signal detection sensitivity. The digital down-conversion performs orthogonal digital down-conversion processing on the pulse signal to convert the high-frequency signal into a low-frequency signal for subsequent processing. The multi-phase filter performs orthogonal digital down-conversion processing on the pulse signal. The signal is processed by multi-phase filtering, the modulus of the pulse signal is calculated, and the detected pulse signal is gated; finally, the time-frequency correlation module performs short-time Fourier transform on the gated output pulse signal, uses saturated pulses to detect the frequency points in the short-time Fourier spectrum, and performs time-frequency correlation on the detected frequency points, so as to obtain the PDW parameter information of multiple pulse signals: center frequency (Fc), pulse width (PW), bandwidth (BW), arrival time (TOA) parameter information, and the signal time domain resolution is the short-time Fourier step value, which realizes the simultaneous detection of pulse signals in the time domain and frequency domain to reduce the signal false alarm rate and reduce the resource consumption of FPGA.

[0054] In this embodiment, complex channelization even arrangement is used to obtain complex signal data information. Specifically, assuming that the input signal is s(n), the low-pass filter impulse response is h(n), the number of channels is K, the decimation rate is D, and the bandwidth of the channelization filter is 2π / K. When the decimation rate D=K is the critical decimation, Wk=2πk / K in the even arrangement channelization efficient structure, the channelization formula in the even arrangement is derived as follows: ,in , substituting Wk=2πk / K into .

[0055] In this embodiment, the short-time Fourier transform is to add a window function to the pulse signal, that is, to perform Fourier transform on a pulse signal with a short time interval; the window function is translated on the entire time axis as the time t changes, thereby obtaining the frequency domain relationship of the pulse signal in a short time near any position; x(t) represents the input signal, w(t) represents the impulse response of the window function, and the short-time Fourier transform expression is: Signal analysis usually adopts discrete form. Assume that the discrete time series of the input signal is x(n), the impulse response of the window function is w(n), and its length is N. The translation of the window function on the time axis is equivalent to the translation of the signal on the time axis. The mathematical operation flow structure is expressed as follows: Figure 5 .

[0056] The present invention adopts a method based on the combination of multiphase filtering and channelization to calculate the instantaneous frequency of the pulse signal, and simultaneously obtains the PDW information of the signal by means of time-frequency association, and uses a saturated pulse as an STFT detection enable signal to reduce the false alarm rate of the signal.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-signal detection method based on polyphase filtering and STFT, characterized in that: The multi-signal detection method based on polyphase filtering and STFT comprises the following steps: Collect multiple pulse signals; Performing digital channelization processing on the plurality of pulse signals: sequentially performing extraction and down-conversion, orthogonal down-conversion, and multi-phase filtering processing on the plurality of pulse signals; The multiple pulse signals are subjected to short-time Fourier transform, and the frequency points in the short-time Fourier spectrum are time-frequency correlated using saturated pulses to obtain the PDW parameter information of the multiple pulse signals.

2. The multi-signal detection method based on polyphase filtering and STFT according to claim 1, characterized in that: The steps of the time-frequency association algorithm are specifically as follows: Set up the time-frequency library; Get the signal frequency within a short period of time; Determine whether the signal frequency matches the signal frequency in the time-frequency library, if so, update the PDW parameter information of the signal frequency, otherwise, output the PDW parameter information.

3. The multi-signal detection method based on polyphase filtering and STFT according to claim 2, characterized in that: The PDW parameter information includes center frequency, pulse width, bandwidth and arrival time parameter information.

4. A multi-signal detection system based on polyphase filtering and STFT, characterized in that: The multi-signal detection system based on polyphase filtering and STFT is used to implement the multi-signal detection method based on polyphase filtering and STFT as claimed in any one of claims 1 to 3, and the multi-signal detection system based on polyphase filtering and STFT comprises: A signal collector, the signal collector is used to collect multiple pulse signals; A digital channelization module, the digital channelization module is connected to the signal receiver, and the digital channelization module is used to perform digital channelization processing on the plurality of pulse signals; A time-frequency association module, the time-frequency association module is connected to the digital channelization module, and the time-frequency association module is used to perform time-frequency association processing on the multiple pulse signals to output a PDW parameter signal.

5. The multi-signal detection system based on polyphase filtering and STFT according to claim 4, characterized in that: The digital channelization module comprises a decimator, a digital down converter and a polyphase filter, wherein the digital down converter is connected to the decimator and the polyphase filter respectively.

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