A method and system for passive positioning of a moving single-station with unknown external radiation source

Abstract

The present invention provides a method and system for passive positioning of a moving single-station unknown external radiation source. The method performs correlation accumulation and incoherent accumulation on the direct wave signal and target reflection signal of the external radiation source radar signal to highlight weak signals, thereby improving the system's anti-noise and anti-clutter performance. The method achieves target position solution by estimating the arrival angle of the direct wave signal energy peak point of the external radiation source signal at two moments, estimating the arrival time difference between the direct signal energy peak point and the target reflection signal energy peak point, and estimating the arrival angle difference between the direct signal energy peak point and the target reflection signal energy peak point. This method reduces the need for prior knowledge of the external radiation source, improves detection capability and accuracy, facilitates positioning and tracking, does not require multi-station collaboration, is applicable to more complex scenarios, reduces system cost, and has high engineering feasibility.

Description

Technical Field

[0001] The present invention relates to the field of electronic reconnaissance technology, and in particular to a method and system for passive positioning of a moving single-station unknown external radiation source. Background Art

[0002] Passive positioning based on external radiation source illumination is currently a popular research direction in electronic countermeasure reconnaissance. The external radiation source positioning system itself does not actively radiate electromagnetic wave signals outward, but uses the electromagnetic wave signals of radiation sources that already exist in the external environment as non-cooperative radar transmission signals to conduct target reconnaissance and positioning.

[0003] Part of the electromagnetic waves emitted by the external radiation source is directly received by the receiving station, and the other part will be received by the receiving station after being reflected and scattered when encountering the target in the air. The receiving station uses the direct waves from the external radiation source and the reflected and scattered signals of the external radiation source irradiating the detected target. The direct waves from the external radiation source and the reflected signals from the external radiation source to the detected target have weak energy, low signal-to-noise ratio, and low signal-to-clutter ratio, which will lead to insufficient detection distance of the receiving station and the problem of the receiving station not being able to detect the external radiation source and the reflected waves of the target.

[0004] When locating the target position, one type requires multiple receiving stations to cooperate in positioning, which will increase the system cost and complexity, and it is also difficult to achieve the coordination of large amounts of real-time data between multiple stations; the other type relies on a single station to estimate the wave direction and time difference at multiple times, but the joint solution of multiple times will have a time delay, resulting in large positioning accuracy errors, which is not conducive to positioning and tracking. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a method and system for passive positioning of an unknown external radiation source by a moving single station, which does not require the cooperation of multiple stations and is conducive to positioning and tracking.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for passive positioning of a moving single-station of an unknown external radiation source, comprising:

[0008] S1, FPGA chip collects the signal AD from the auxiliary channel, performs digital channelization processing, performs signal sorting, pulse identification, and extracts the pulse description word information of repetition period T, bandwidth B, and pulse width τ;

[0009] S2. Performing digital orthogonal down-conversion on the digital signals of the four interferometer channels after AD acquisition according to the pulse description word information to obtain baseband IQ signals;

[0010] S3, the extracted pulse description word information and baseband IQ signal are sent to the DSP through the SRIO high-speed interface, and a matched filter factor is constructed in the DSP to perform autocorrelation processing;

[0011] Coherently accumulating the results of the autocorrelation processing, and implementing a Doppler bandpass filter by means of FFT to suppress wide-spectrum clutter, receiver frequency conversion component phase noise, and system noise, while suppressing ground clutter and improving the signal-to-clutter ratio or signal-to-noise ratio;

[0012] At the signal peak point, the phase information of the four-way baseband IQ signals is obtained, and the signal direction is estimated with the help of the interferometer characteristics.

[0013] Furthermore, it also includes:

[0014] S4, a single moving receiving station, the kth external radiation source repetition period T; extracting the energy peak point of the direct wave signal of the four-way interferometer channel, and performing direction finding based on the baseband IQ data corresponding to the energy peak point of the direct wave signal to obtain the estimated direction of the incoming wave θ T1 , the receiving station position coordinate corresponding to the direct wave signal energy peak point is marked as (x1,0);

[0015] Furthermore, after n repetition cycles, the energy peak points of the direct wave signal and the target reflected wave of the four-way interferometer channel are measured and extracted in the k+n+1th cycle, and the estimated direction of the direct wave signal energy peak point θ is obtained. (n+1)T1 , the target transmits the wave signal energy peak point to estimate the wave direction θ (n+1)T2 The peak energy point of the direct signal and the peak energy point of the target reflected signal correspond to the same receiving station position coordinates, which are recorded as (x1+vnT,0); then the position coordinates of the external radiation source A (x A ,y A )for:

[0016]

[0017]

[0018] At this moment, the distance from the external radiation source to the receiving station is:

[0019]

[0020] Furthermore, in the k+n+1th cycle, the arrival time difference between the direct signal energy peak point and the target reflected signal energy peak point is estimated τ0, and the path difference Δl=cτ0 between the direct signal energy peak point and the target reflected signal energy peak point is calculated, where c is the speed of light, and the path l of the reflected signal is calculated. sum =Δl+l1, where l1 is the distance from the external radiation source to the receiving station.

[0021] Furthermore, in the k+n+1th cycle, the incoming wave direction estimation of the direct wave signal energy peak point is obtained Get the target transmission wave signal energy peak point to estimate the incoming wave direction Calculate the arrival angle difference between the two energy peak points:

[0022]

[0023] Furthermore, the distance l3 between the target and the receiving station is obtained by the distance l1 from the external radiation source to the receiving station, the path difference Δl between the reflected signal and the direct wave signal, and the arrival angle difference between the reflected signal and the direct wave signal. The calculation formula is:

[0024]

[0025] The final target position coordinates are:

[0026]

[0027]

[0028] Furthermore, a system for passive positioning of a single-station moving object for an unknown external radiation source, wherein the system is used to implement a method for passive positioning of a single-station moving object for an unknown external radiation source, further comprising:

[0029] A four-way interferometer antenna array is used to receive direct waves from an external radiation source and reflected echo signals from a target;

[0030] Auxiliary channel, used for purifying direct wave echo signals;

[0031] Receiver frequency conversion component module, used for down-conversion and amplification of RF echo signals;

[0032] Digital processing components adopt AD+FPGA+DSP architecture;

[0033] AD is responsible for collecting and receiving the intermediate frequency signal processed by the frequency conversion component module;

[0034] The FPGA chip performs signal preprocessing operations and simultaneously controls the working status of the receiving frequency conversion component module;

[0035] DSP performs coherent accumulation and incoherent accumulation;

[0036] The terminal module communicates with the digital signal processing component module through Ethernet, exchanges work control command parameters, and receives the returned signal processing results.

[0037] The beneficial effects of the present invention are as follows: the present invention aims to solve the problem that under the condition that the position of the external radiation source is unknown, the characteristics of the external radiation source are extracted by sorting, the signal-to-noise ratio and the signal-to-clutter ratio are improved with the help of the signal characteristics of the external radiation source, and the energy peak point of the echo signal is obtained; the arrival angle of the direct wave signal energy peak point of the external radiation source signal in the kth repetition period of the moving single station is estimated, the arrival angle of the direct wave signal energy peak point of the external radiation source signal in the k+nT+1th repetition period is estimated, the arrival angle of the target reflection signal energy peak point is estimated, and the arrival time difference between the direct signal energy peak point and the target reflection signal energy peak point is estimated. Only calculations with an interval of nT two repetition periods are required to realize the target position solution, which reduces the need for prior knowledge of the external radiation source, improves the detection capability and accuracy, is conducive to positioning and tracking, does not require multi-station combination, can be applied to more complex scenarios, also reduces the system cost, and has high engineering feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a method for passive positioning of a moving single-station with an unknown external radiation source;

[0039] Figure 2 A block diagram of a system for passive positioning of a single moving station with an unknown external radiation source;

[0040] Figure 3 Create a block diagram for digital signal processing components;

[0041] Figure 4 It is the rectangular coordinate system diagram of the scene. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] See also Figure 1 , a method for passive positioning of a single moving station with an unknown external radiation source, comprising:

[0044] S1, FPGA chip collects the signal AD from the auxiliary channel, processes it into digital channels, performs signal sorting and pulse identification, and extracts the pulse description word information of repetition period T, bandwidth B, and pulse width τ;

[0045] S2. Performing digital orthogonal down-conversion on the digital signals of the four interferometer channels after AD acquisition according to the pulse description word information to obtain baseband IQ signals;

[0046] S3, the extracted pulse description word information and baseband IQ signal are sent to the DSP through the SRIO high-speed interface, and a matched filter factor is constructed in the DSP to perform autocorrelation processing;

[0047] Coherently accumulating the results of the autocorrelation processing, and implementing a Doppler bandpass filter by means of FFT to suppress wide-spectrum clutter, receiver frequency conversion component phase noise, and system noise, while suppressing ground clutter and improving the signal-to-clutter ratio or signal-to-noise ratio;

[0048] At the signal peak point, the phase information of the four-way baseband IQ signals is obtained, and the signal direction is estimated with the help of the interferometer characteristics.

[0049] Also includes:

[0050] S4, a single moving receiving station, the kth external radiation source repetition period T; extracting the energy peak point of the direct wave signal of the four-way interferometer channel, and performing direction finding based on the baseband IQ data corresponding to the energy peak point of the direct wave signal to obtain the estimated direction of the incoming wave θ T1 , the receiving station position coordinate corresponding to the direct wave signal energy peak point is marked as (x1,0);

[0051] After n repetition cycles, the energy peak point of the direct wave signal of the four-way interferometer channel and the target reflected wave peak point are measured and extracted in the k+n+1 cycle, and the estimated direction of the direct wave signal energy peak point θ is obtained. (n+1)T1 , the target transmits the wave signal energy peak point to estimate the wave direction θ (n+1)T2 The peak energy point of the direct signal and the peak energy point of the target reflected signal correspond to the same receiving station position coordinates, which are recorded as (x1+vnT,0); then the position coordinates of the external radiation source A (x A ,y A )for:

[0052]

[0053]

[0054] At this moment, the distance from the external radiation source to the receiving station is:

[0055]

[0056] In the k+n+1th cycle, the arrival time difference between the direct signal energy peak point and the target reflected signal energy peak point is estimated τ0, and the path difference Δl=cτ0 between the direct signal energy peak point and the target reflected signal energy peak point is calculated, where c is the speed of light, and the path l of the reflected signal is calculated. sum =Δl+l1, where l1 is the distance from the external radiation source to the receiving station.

[0057] In the k+n+1th cycle, the incoming wave direction estimation is obtained at the energy peak point of the direct wave signal. Get the target transmission wave signal energy peak point to estimate the incoming wave direction Calculate the arrival angle difference between the two energy peak points:

[0058]

[0059] The distance l3 between the target and the receiving station is obtained by the distance l1 from the external radiation source to the receiving station, the path difference Δl between the reflected signal and the direct wave signal, and the arrival angle difference between the reflected signal and the direct wave signal. The calculation formula is:

[0060]

[0061] The final target position coordinates are:

[0062]

[0063]

[0064] A system for passive positioning of a single moving station of an unknown external radiation source, wherein the system is used to implement the method for passive positioning of a single moving station of an unknown external radiation source, further comprising:

[0065] A four-way interferometer antenna array 101 is used to receive direct waves from an external radiation source and reflected echo signals from a target;

[0066] Auxiliary channel 102, used for purifying direct wave echo signals;

[0067] The receiving frequency conversion component module 103 is used for down-converting and amplifying the radio frequency echo signal;

[0068] The digital processing component 104 adopts the architecture of AD+FPGA+DSP;

[0069] AD1041 is responsible for collecting and receiving the intermediate frequency signal processed by the frequency conversion component module;

[0070] The FPGA1042 chip performs signal preprocessing operations and simultaneously controls the working state of the receiving frequency conversion component module;

[0071] DSP1043 performs coherent accumulation and incoherent accumulation;

[0072] The terminal module communicates with the digital signal processing component module through Ethernet, exchanges work control command parameters, and receives the returned signal processing results.

[0073] Example 1

[0074] See also Figure 2 and Figure 3The five ADs collect the intermediate frequency signal of one auxiliary channel and the intermediate frequency signals of four interferometer channels, respectively. After the FPGA chip collects the AD signals from the auxiliary channels, it performs digital channelization processing, signal sorting, intra-pulse identification, and extracts pulse descriptors such as repetition period T, bandwidth B, and pulse width τ. Based on the pulse descriptors, the four interferometer channels perform digital orthogonal down-conversion on the digital signals collected by the ADs to obtain baseband IQ signals. The extracted pulse descriptors and baseband IQ signals are sent to the DSP via the SRIO high-speed interface. A matched filter factor is constructed in the DSP, and the results of the autocorrelation processing are coherently accumulated. The FFT is used to implement a Doppler bandpass filter to suppress broadband clutter, phase noise of the receiving frequency conversion module, and system noise. Ground clutter is also suppressed to improve the signal-to-clutter ratio (SCR). At the signal energy peak, phase information is obtained from the four baseband IQ signals. The interferometer characteristics are used to estimate the arrival direction of the direct wave from the external radiation source and the arrival direction of the target reflected wave, and the arrival time difference between the direct signal and the target reflected signal is estimated.

[0075] like Figure 4 As shown in the figure, a rectangular coordinate system is established with the movement direction of a single receiving station as the horizontal axis. First, within the repetition period T of the kth external radiation source, the energy peak point of the direct wave signal of the four-way interferometer channel and the peak point of the target reflected wave are extracted. The direction of the incoming wave is estimated by the baseband IQ data corresponding to the energy peak point of the direct wave signal. T1 , the receiving station position coordinate corresponding to the direct wave signal energy peak point is marked as (x1,0);

[0076] After n repetition cycles, where n is the order of coherent accumulation, n≥1; repeat the above steps to obtain the direct wave signal energy peak point incoming wave direction estimation θ (n+1)T1 , the target transmits the wave signal energy peak point to estimate the wave direction θ (n+1)T2 , the arrival time difference between the direct signal energy peak point and the target reflected signal energy peak point is estimated as τ0, the receiving station movement speed v, since τ0≤nT, nT≤1s, the direct signal energy peak point and the target reflected signal energy peak point correspond to the receiving station position coordinates that are approximately the same, which can be recorded as (x1+vnT,0); then the position coordinates of the external radiation source A (x A ,y A ) is calculated as follows:

[0077]

[0078]

[0079] Get the distance from the radiation source to the receiving station outside the k+n+1th repetition period:

[0080]

[0081] like Figure 4 As shown, in the k+n+1th repetition frequency cycle, the arrival time difference estimate τ0 of the direct signal energy peak point and the target reflected signal energy peak point is obtained, and the calculated path difference Δl=cτ0 of the direct signal energy peak point and the target reflected signal energy peak point is obtained, where c is the speed of light.

[0082] Calculate the path l of the reflected signal sum =Δl+l1.

[0083] The energy peak point of the direct wave signal is measured at the k+n+1th cycle to estimate the incoming wave direction. Get the target transmission wave signal energy peak point to estimate the incoming wave direction Calculate the arrival angle difference between the two energy peak points

[0084] The distance l3 between the target and the receiving station is obtained by the distance l1 from the external radiation source to the receiving station, the path difference Δl between the reflected signal and the direct wave signal, and the arrival angle difference between the reflected signal and the direct wave signal. The calculation formula is:

[0085] The final target position coordinates are:

[0086]

[0087]

[0088] After multiple measurements, multiple sets of position coordinates (x i ,y i ), i-1,...n. In order to reduce the positioning error caused by noise, parameter measurement, etc., this system invention adopts a positioning result correction method based on mean filtering, defining

[0089] The positioning result calculation method is:

[0090] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for passive positioning of a single moving station with an unknown external radiation source, characterized in that: include: S1, FPGA chip collects the signal AD from the auxiliary channel, processes it into digital channels, performs signal sorting and pulse identification, and extracts the pulse description word information of repetition period T, bandwidth B, and pulse width τ; S2. Performing digital orthogonal down-conversion on the digital signals of the four interferometer channels after AD acquisition according to the pulse description word information to obtain baseband IQ signals; S3, the extracted pulse description word information and baseband IQ signal are sent to the DSP through the SRIO high-speed interface, and a matched filter factor is constructed in the DSP to perform autocorrelation processing; Coherently accumulating the results of the autocorrelation processing, and implementing a Doppler bandpass filter by means of FFT to suppress wide-spectrum clutter, receiver frequency conversion component phase noise, and system noise, while suppressing ground clutter and improving the signal-to-clutter ratio or signal-to-noise ratio; At the signal peak point, the phase information of the four-way baseband IQ signal is obtained, and the signal direction is estimated by using the interferometer characteristics; Also includes: S4, a single moving receiving station, the kth external radiation source repetition period T; extracting the energy peak point of the direct wave signal of the four-way interferometer channel, and performing direction finding based on the baseband IQ data corresponding to the energy peak point of the direct wave signal to obtain the estimated direction of the incoming wave θ T1 , the receiving station position coordinate corresponding to the direct wave signal energy peak point is marked as (x1,0); After n repetition cycles, the energy peak point of the direct wave signal of the four-way interferometer channel and the target reflected wave peak point are measured and extracted in the k+n+1th cycle, and the estimated direction of the direct wave signal energy peak point θ is obtained. (n+1)T1 , the target transmission wave signal energy peak point incoming wave direction estimation θ (n+1)T2 , the direct signal energy peak point is recorded as (x1+vnT,0); then the position coordinates of the external radiation source A (x A ,y A )for: At this moment, the distance from the external radiation source to the receiving station is: In the k+n+1th cycle, the arrival time difference between the direct signal energy peak point and the target reflected signal energy peak point is estimated τ0, and the path difference Δl=cτ0 between the direct signal energy peak point and the target reflected signal energy peak point is calculated, where c is the speed of light, and the path l of the reflected signal is calculated. sum =Δl+l1, where l1 is the distance from the external radiation source to the receiving station; In the k+n+1th cycle, the incoming wave direction estimation is obtained at the energy peak point of the direct wave signal. Get the target transmission wave signal energy peak point to estimate the incoming wave direction Calculate the arrival angle difference between the two energy peak points: The distance l3 between the target and the receiving station is obtained by the distance l1 from the external radiation source to the receiving station, the path difference Δl between the reflected signal and the direct wave signal, and the arrival angle difference between the reflected signal and the direct wave signal. The calculation formula is: The final target position coordinates are: x T =x2-l3×cos(θ n+1T2 ); y T =l3×sin(θ n+1T2 )。 2. A system for passive positioning of a single moving station with an unknown external radiation source, characterized in that: The system is used to implement the method for moving single-station passive positioning of an unknown external radiation source as claimed in claim 1, further comprising: A four-way interferometer antenna array is used to receive direct waves from an external radiation source and reflected echo signals from a target; Auxiliary channel, used for purifying direct wave echo signals; Receiver frequency conversion component module, used for down-conversion and amplification of RF echo signals; Digital processing components adopt AD+FPGA+DSP architecture; AD is responsible for collecting and receiving the intermediate frequency signal processed by the frequency conversion component module; The FPGA chip performs signal preprocessing operations and simultaneously controls the working status of the receiving frequency conversion component module; DSP performs coherent accumulation and incoherent accumulation; The terminal module communicates with the digital signal processing component module through Ethernet, exchanges work control command parameters, and receives the returned signal processing results.

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