CN117784063A - Simple single-channel passive bistatic radar system and processing method - Google Patents
Simple single-channel passive bistatic radar system and processing method Download PDFInfo
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Abstract
The invention relates to a simple single-channel passive bistatic radar system and a processing method, and belongs to the technical field of passive radars. In order to solve the problems of complex structure and high cost of the traditional passive bistatic radar system, the simple single-channel passive bistatic radar system with simple structure and low cost is provided. The system comprises an antenna module, a signal frequency conversion module, a signal acquisition processing module and a data processing display PC terminal; the signal frequency conversion module comprises a signal frequency conversion unit and a clock and local oscillator unit; the signal acquisition processing module comprises a signal acquisition unit, a main control unit and an interface unit; the data processing display PC terminal is used for controlling the whole system and analyzing, processing and displaying the acquired data.
Description
Technical Field
The invention relates to a simple single-channel passive bistatic radar system and a processing method, and belongs to the technical field of passive radars.
Background
The radar signal is used as a passive bistatic radar of a non-cooperative radiation source, and a local receiving system is used for receiving a direct wave reference signal and a target echo, so that detection and tracking of a target are realized. Compared with the traditional active radar system, the system has the advantages of no emission, low power consumption, low cost, light weight and the like, and can keep reconnaissance and monitoring of the battlefield environment when electromagnetic silence occurs.
The conventional passive bistatic radar system generally adopts two channels (a direct wave channel and a target channel) to respectively receive a direct wave reference signal and a target echo, and two sets of antennas and two sets of receivers are needed, so that the system structure is complex, and the cost is correspondingly increased. Radar signals are typically characterized by a large bandwidth and good compression ratio, so they provide enhanced range resolution. Because the common radar waveforms are deterministic, the bistatic configuration does not substantially require a direct-wave reference channel to detect targets. The a priori knowledge of the deterministic waveform allows the passive receiver to be matched with the opportunistic illumination source to generate a doppler plot, thereby enabling detection of moving objects.
Disclosure of Invention
The invention aims to solve the problems of complex structure and high cost of the traditional passive bistatic radar system in the prior art, and provides a simple single-channel passive bistatic radar system with simple structure and low cost.
In order to solve the problems, the application is realized by the following technical scheme:
the simple single-channel passive bistatic mine system is characterized in that: the system comprises an antenna module, a signal frequency conversion module, a signal acquisition processing module and a data processing display PC terminal;
the antenna module is used for receiving signals;
the signal frequency conversion module comprises a signal frequency conversion unit and a clock and local oscillator unit;
the frequency conversion unit is a single-channel receiver, receives signals of the antenna module, processes the signals and transmits the processed signals to the signal acquisition processing module, and simultaneously receives signals of the clock and the local oscillation unit;
the local oscillator unit receives signals of the signal acquisition and processing module and transmits the signals to the signal acquisition and processing module and the frequency conversion unit;
the signal acquisition processing module comprises a signal acquisition unit, a main control unit and an interface unit;
the acquisition unit receives signals of the frequency conversion unit, transmits the signals to the main control unit and the interface unit, and simultaneously receives signals of the interface unit, the clock and the local oscillation unit;
the interface unit transmits signals of the acquisition unit to the main control unit and the data processing display PC terminal, and transmits signals of the main control unit and the data processing display PC terminal to the acquisition unit;
the data processing display PC terminal realizes the control of the whole system and analyzes, processes and displays the acquired data;
preferably, the antenna module adopts a simple horn antenna, is a directional antenna, has the signal receiving capability of 1-2 GHz, and aims at an L-band warning radar irradiation source;
preferably, the signal frequency conversion unit converts, amplifies and filters the signal received by the antenna into an intermediate frequency analog signal;
the clock and local oscillator unit generates various reference clock signals;
preferably, the signal frequency conversion module consists of an L-band field amplifier, an L-band frequency synthesizer and an L-band frequency converter;
the L-band field amplifier is used for amplifying the L-band direct wave and target echo radio frequency signals received by the antenna; the L-band field amplifier comprises two filters, a limiter, and a low noise amplifier. Radio frequency input frequency: 1100 MHz-1400 MHz, gain: 15dB or more, noise coefficient: less than or equal to 3dB;
the L-band frequency synthesizer adopts a phase-locked loop to output a path of 1 local oscillator and a path of 2 local oscillators, wherein the 1 local oscillator outputs frequency: 1600 MHz-1900 MHz,1MHz steps, and the frequency is controlled; 2 local oscillation output frequency: 640MHz; local oscillator output level: not less than 0dBm;
the L-band double-channel frequency converter is used for receiving L-band signals and outputting intermediate frequency signals through frequency conversion, amplification and filtering;
preferably, the acquisition unit converts the intermediate frequency analog signal which is processed by the signal frequency conversion unit and is mixed with the direct wave and the target echo into a baseband digital signal;
the main control unit calculates various commands and parameters and controls each module to work normally according to a set time sequence;
the interface unit adopts a PCIEx4 bus interface to realize external connection of the system;
the signal acquisition processing module performs A/D conversion on the intermediate frequency analog signal mixed with the direct wave and the target echo output by the signal frequency conversion module, sends the intermediate frequency analog signal into the FPGA for preprocessing, and then transmits acquired IQ data to the PC terminal for analysis, processing and display through the PCIEx4 bus interface.
The simple single-channel passive bistatic mine system IQ data processing method comprises the following steps:
1. single channel pulse compression
The pulse compression module performs simultaneous pulse compression processing on single-channel IQ data mixed with the direct wave and the target echo, and outputs compressed narrow pulse mixed with the direct wave and the target echo;
2. direct wave extraction and separation
When the first step is completed, according to the time domain characteristics, when the target is far away from the receiving and transmitting antenna or the pulse width of the pulse signal is narrow, the direct wave and the target echo signal can be separated in time, so that the direct wave and the target echo signal are separated by adopting a time window technology;
3. time synchronization processing
Extracting the separated direct wave signal by the second step, and extracting time synchronization information from the direct wave signal, wherein the time synchronization information comprises arrival time and pulse repetition interval information, and outputting pulse repetition interval trigger pulses synchronized with the direct wave after time synchronization processing;
4. direction synchronization processing
Extracting antenna azimuth synchronization information from the separated direct wave signals by utilizing the second step, forming a pulse peak value when a radar antenna sweeps a receiver, and utilizing the maximum peak value to complete azimuth synchronization and display data;
5. MTI and MTD moving object processing
Processing the MTI filter by adopting three pulses, and compensating the Doppler frequency of echo pulses before the MTI processing;
the MTD is achieved by FFT processing of pulses with multiple adjacent pulse repetition periods, which corresponds to coherent accumulation of echo bursts;
the main purpose of the moving object display (MTI) technology is to improve the detection capability of radar moving objects, filter out static objects and clutter and display the moving objects;
the main purpose of the moving object processing (MTD) technology is to obtain a range Doppler image (R-D image) of a moving object for data display;
6. video accumulation
Accumulating the envelope amplitudes of the echo signals with the video accumulated to 6-12 identical distance units;
7. constant false alarm detection
And adopting a unit average maximum selection constant false alarm detection (GO-CFAR) detector to perform target constant false alarm detection, reducing the false alarm rate and the false alarm rate, and performing data display in the form of difficult background power level estimation in the CFAR detection threshold forming process.
Preferably, the single channel pulse compression includes the following two methods:
reconstructing a direct wave reference signal according to a known prior parameter or an estimated parameter, wherein the direct wave reference signal and an echo signal complete pulse compression;
and secondly, directly intercepting a section of complete direct wave sample signal in the IQ data, and completing pulse compression with the echo signal, which is equivalent to cross-correlation of the sample signal and the echo signal.
Preferably, the direct wave extraction and separation adopts the following steps: and extracting and separating the direct wave from single-channel IQ data mixed with the direct wave and the target echo by using the condition constraints such as the frequency, the pulse width, the amplitude, the Pulse Repetition Interval (PRI) and the phase difference of the direct wave.
Preferably, the method for time synchronization processing comprises the following steps: estimating the arrival time of each received pulse by thresholding the received signal after pulse compression and arrival time training has occurred; the pulse repetition interval uses the time difference between adjacent arrival times.
Preferably, the azimuth synchronization processing method comprises the following steps:
for the case of uniform circumferential rotation of the transmitting station antenna: in the first few weeks of antenna scanning, transmitting a transmission beam direct pulse train to an azimuth synchronizer, and measuring an average value of antenna scanning time as a predicted value of the next antenna scanning period, wherein the method specifically comprises the following steps: 1) In a sweep frequency mode, PDW parameter measurement is carried out on signals received by a direct wave channel, and parameters such as frequency, amplitude and the like of the measured signals are obtained after pulse sorting; finding out the signal with the highest interception times from the parameters, and continuing to measure the antenna scanning period; if a plurality of signals are selected, the signal with the highest interception frequency is analyzed by the current setting;
2) For the situation that the antenna of the radiation source performs uniform circumferential scanning, measuring to obtain the antenna scanning period of the radiation source based on the signal amplitude, and adopting an autocorrelation method;
3) After the antenna scanning period is obtained, comparing whether the current pulse is a locked radiation source or not every time a PDW is detected by the direct wave channel, and mainly comparing 3 parameters of carrier frequency, bandwidth and pulse width; if the signal belongs to the locked radiation source, judging whether the signal amplitude is close to the maximum value in the early measurement process, and taking the condition that the amplitude value is close to the maximum value of the historical amplitude as a criterion;
4) If the PDW and the scanning period of the mechanical scanning radar can be measured, and the power spectrum shows that the locked signal is correct, a sampling enabling signal is generated, the period of the enabling signal is the antenna scanning period of the radiation source, the time of the high level is the integral multiple of the PRI of the measured signal, the sampling is ensured to be started when the antenna of the radiation source is opposite to the receiver, the antenna scanning is slow, and the sampling delay is the time required for pointing to the target monitoring area after the estimated maximum value is scanned through the receiver.
According to the simple single-channel passive bistatic radar system, the direct wave channel and the target channel are combined into one channel, and the detection of the target is completed through single-channel pulse compression, direct wave extraction and separation, synchronous processing, MTI, MTD, CFAR and other processing, so that the double channels are reduced to be single channels, the equipment is simple, the cost of a receiver is reduced by half, the processing method is simple, the weight is light, the size is small, and the system is convenient for carrying in an external field.
Drawings
Fig. 1: the structure of the invention is schematically shown;
fig. 2: an L-band field amplifier schematic block diagram;
fig. 3: an L-band frequency synthesizer schematic block diagram;
fig. 4: an L-band frequency converter schematic block diagram;
fig. 5: a signal acquisition processing module;
fig. 6: single-channel IQ data analysis and processing flow chart;
description of the embodiments
The following description of the present invention will be given with reference to the accompanying drawings, which are used to further explain the constitution of the present invention.
Example 1. The simple single-channel passive bistatic mine system shown in fig. 1 is characterized in that: the system comprises an antenna module, a signal frequency conversion module, a signal acquisition processing module and a data processing display PC terminal;
the antenna module is used for receiving signals;
the signal frequency conversion module comprises a signal frequency conversion unit and a clock and local oscillator unit;
the frequency conversion unit is a single-channel receiver, receives signals of the antenna module, processes the signals and transmits the processed signals to the signal acquisition processing module, and simultaneously receives signals of the clock and the local oscillation unit;
the local oscillator unit receives signals of the signal acquisition and processing module and transmits the signals to the signal acquisition and processing module and the frequency conversion unit;
the signal acquisition processing module comprises a signal acquisition unit, a main control unit and an interface unit;
the acquisition unit receives signals of the frequency conversion unit, transmits the signals to the main control unit and the interface unit, and simultaneously receives signals of the interface unit, the clock and the local oscillation unit;
the interface unit transmits signals of the acquisition unit to the main control unit and the data processing display PC terminal, and transmits signals of the main control unit and the data processing display PC terminal to the acquisition unit;
the data processing display PC terminal realizes the control of the whole system and analyzes, processes and displays the acquired data;
the antenna module adopts a simple horn antenna, is a directional antenna, has the signal receiving capability of 1-2 GHz and aims at an L-band warning radar irradiation source;
the signal frequency conversion unit converts, amplifies and filters signals received by the antenna into intermediate frequency analog signals;
the clock and local oscillator unit generates various reference clock signals;
the signal frequency conversion module consists of an L-band field amplifier, an L-band frequency synthesizer and an L-band frequency converter;
the L-band field amplifier is used for amplifying the L-band direct wave and target echo radio frequency signals received by the antenna; the L-band field amplifying circuit comprises two filters, a limiter and a low noise amplifier. Radio frequency input frequency: 1100 MHz-1400 MHz, gain: 15dB or more, noise coefficient: less than or equal to 3dB, and the principle is shown in figure 2;
the L-band frequency synthesizer adopts a phase-locked loop to output a path of 1 local oscillator and a path of 2 local oscillators, wherein the 1 local oscillator outputs frequency: 1600 MHz-1900 MHz,1MHz steps, and the frequency is controlled; 2 local oscillation output frequency: 640MHz; local oscillator output level: more than or equal to 0dBm, the principle of which is shown in figure 3;
the quality of the near-end phase noise of the vibration source mainly depends on the output phase noise of the reference crystal oscillator, and the excellent reference crystal oscillator index can improve the overall performance of the whole receiving channel. The local oscillator selects a PLL chip integrating the VCO, adopts 20MHz as phase discrimination frequency, adopts a passive low-pass filter as loop filtering, and obtains better phase noise index and spurious suppression index by reasonably configuring the values of corresponding registers.
The L-band double-channel frequency converter is used for receiving L-band signals and outputting intermediate frequency signals through frequency conversion, amplification and filtering;
radio frequency input frequency: 1100 MHz-1400 MHz; local oscillator 1 input frequency: 160 MHz to 1900MHz; local oscillator 1 input level: 0-4 dBm; local oscillator 2 input frequency: 640MHz, local oscillator 2 input level: 0-4 dBm; intermediate frequency output frequency: 140MHz; instantaneous bandwidth of signal: 10MHz. Gain: not less than 85dB; gain control range: 0-100 dB (numerical control); gain control step size: 1dB; gain control error: 1dB; in the receiving link, a 4-stage digital attenuator is placed, the attenuation of each stage of attenuator is 31.5dB, the step is 0.5dB, and the maximum gain error is 0.8dB, and the principle is shown in figure 4.
The acquisition unit converts an intermediate frequency analog signal which is processed by the signal frequency conversion unit and is mixed with the direct wave and the target echo into a baseband digital signal;
the main control unit calculates various commands and parameters and controls each module to work normally according to a set time sequence;
the interface unit adopts a PCIEx4 bus interface to realize external connection of the system;
the signal acquisition processing module performs A/D conversion on the intermediate frequency analog signal mixed with the direct wave and the target echo output by the signal frequency conversion module, sends the intermediate frequency analog signal into the FPGA for preprocessing, and then transmits acquired IQ data to the PC terminal for analysis, processing and display through the PCIEx4 bus interface, and the principle is shown in figure 5.
The signal acquisition subsystem acquires intermediate frequency signals (intermediate frequency 140M and bandwidth is less than 10M) output by the signal frequency conversion unit, the sampling rate parameters are adjustable, DDC digital quadrature is completed on the FPGA chip, and uninterrupted continuous real-time acquisition and storage of IQ data can be realized under the condition that the IQ sampling rate is less than 20M.
Data acquired by the ADC are transmitted to the PC terminal through the PCI-E interface; the radio frequency control adopts a micro rectangular socket, and the socket comprises a power supply interface and a UART control interface for front-end radio frequency; the signal acquisition subsystem is powered by DC+12V, and secondary power supply is provided for the radio frequency module; the dc+12vd supply of the module is from an external independent power supply module.
Example 2. The simple single-channel passive bistatic radar system of embodiment 1 only employs a single-channel receiver, and the target echo and the direct wave share the same receiving channel. Since there is no transmitter and a simple horn antenna is used, the time synchronization PRT trigger pulse and the azimuth code cannot be output by the transmitter. The time synchronization and the azimuth synchronization of the system need to be extracted from the direct arrival wave. The IQ data is subjected to single-channel pulse compression, direct wave extraction and separation, synchronous processing, MTI, MTD, CFAR and the like, so that target detection is completed.
The simple single-channel passive bistatic mine system IQ data processing method shown in FIG. 6 comprises the following steps:
1. single channel pulse compression
The received non-cooperative radar signal is an LFM linear frequency modulation signal which has a larger time-width bandwidth product, and the LFM signal is not modulated and is difficult to obtain narrow pulse and wide bandwidth;
the purpose of pulse compression is to compress a wide pulse signal to obtain a narrow pulse signal, so that the resolution of the radar is improved while the detection distance is ensured, and the detection precision of the radar is ensured;
the pulse compression module performs simultaneous pulse compression processing on single-channel IQ data mixed with the direct wave and the target echo, and outputs compressed narrow pulse mixed with the direct wave and the target echo;
2. direct wave extraction and separation
When receiving signals, the direct wave sidelobe interference exists in a receiver channel, the direct wave intensity is far higher than that of an echo, the direct wave sidelobe can cover a target echo, and at the moment, the direct wave needs to be separated from the target;
when the first step is completed, according to the time domain characteristics, when the target is far away from the receiving and transmitting antenna or the pulse width of the pulse signal is narrow, the direct wave and the target echo signal can be separated in time, so that the direct wave and the target echo signal are separated by adopting a time window technology;
3. time synchronization processing
Extracting the separated direct wave signal by the second step, and extracting time synchronization information from the direct wave signal, wherein the time synchronization information comprises arrival time and pulse repetition interval information, and outputting pulse repetition interval trigger pulses synchronized with the direct wave after time synchronization processing;
4. direction synchronization processing
Extracting antenna azimuth synchronization information from the separated direct wave signals by utilizing the second step, forming a pulse peak value when a radar antenna sweeps a receiver, and utilizing the maximum peak value to complete azimuth synchronization;
5. MTI and MTD moving object processing
Processing the MTI filter by adopting three pulses, and compensating the Doppler frequency of echo pulses before the MTI processing;
the MTD is achieved by FFT processing of pulses with multiple adjacent pulse repetition periods, which corresponds to coherent accumulation of echo bursts;
the main purpose of the moving object display (MTI) technology is to improve the detection capability of radar moving objects, filter out static objects and clutter and display the moving objects;
the main purpose of moving object processing (MTD) techniques is to obtain range-doppler plots (R-D plots) of moving objects;
6. video accumulation
Accumulating the envelope amplitudes of the echo signals with the video accumulated to 6-12 identical distance units;
the intensity of the echo signal received by the receiver is weaker, the signal-to-noise ratio is lower, at the moment, small targets in the echo data can be missed, and the signal-to-noise ratio can be effectively improved by accumulating pulse strings, so that the detection of the small targets is facilitated; although the signal to noise ratio improvement of the coherent accumulation is more obvious compared with the non-coherent video accumulation, the coherent accumulation has higher requirements on the coherence, and is simpler compared with the non-coherent video accumulation;
7. constant false alarm detection
Adopting a unit average maximum selection constant false alarm detection (GO-CFAR) detector to perform target constant false alarm detection to reduce the false alarm rate and false detection rate, and solving the problem of difficult background power level estimation in the CFAR detection threshold forming process;
when detection is carried out under different bistatic angles, clutter energy is unevenly distributed, clutter is easily influenced by clutter abnormal units with suddenly increased power, and the false alarm rate and false detection rate are high; secondly, the complex non-uniform environment formed by the near-shore mountain land/architecture, islands and other strong scattering point distance side lobes causes the problem of difficult background power level estimation in the CFAR detection threshold forming process. Thus, adaptive CFAR detection of targets in a bistatic clutter background is required.
Wherein the single channel pulse compression comprises the following two methods:
reconstructing a direct wave reference signal according to a known prior parameter or an estimated parameter, wherein the direct wave reference signal and an echo signal complete pulse compression;
and secondly, directly intercepting a section of complete direct wave sample signal in the IQ data, and completing pulse compression with the echo signal, which is equivalent to cross-correlation of the sample signal and the echo signal.
The direct wave extraction and separation method comprises the following steps: and extracting and separating the direct wave from single-channel IQ data mixed with the direct wave and the target echo by using the condition constraints such as the frequency, the pulse width, the amplitude, the Pulse Repetition Interval (PRI) and the phase difference of the direct wave.
The time synchronization processing method comprises the following steps: estimating the arrival time of each received pulse by thresholding the received signal after pulse compression and arrival time training has occurred; the pulse repetition interval uses the time difference between adjacent arrival times.
The azimuth synchronization processing method comprises the following steps:
for the case of uniform circumferential rotation of the transmitting station antenna: in the first few weeks of antenna scanning, transmitting a transmission beam direct pulse train to an azimuth synchronizer, and measuring an average value of antenna scanning time as a predicted value of the next antenna scanning period, wherein the method specifically comprises the following steps:
1) In a sweep frequency mode, PDW parameter measurement is carried out on signals received by a direct wave channel, and parameters such as frequency, amplitude and the like of the measured signals are obtained after pulse sorting; finding out the signal with the highest interception times from the parameters, and continuing to measure the antenna scanning period; if a plurality of signals are selected, the signal with the highest interception frequency is analyzed by the current setting;
2) For the situation that the antenna of the radiation source performs uniform circumferential scanning, the antenna scanning period of the radiation source is obtained by measurement based on the signal amplitude, and an autocorrelation method is adopted;
3) After the antenna scanning period is obtained, comparing whether the current pulse is a locked radiation source or not every time a PDW is detected by the direct wave channel, and mainly comparing 3 parameters of carrier frequency, bandwidth and pulse width; if the signal belongs to the locked radiation source, judging whether the signal amplitude is close to the maximum value in the early measurement process, and taking the condition that the amplitude value is close to the maximum value of the historical amplitude as a criterion;
4) If the PDW and the scanning period of the mechanical scanning radar can be measured, and the power spectrum shows that the locked signal is correct, a sampling enabling signal is generated, the period of the enabling signal is the antenna scanning period of the radiation source, the time of the high level is the integral multiple of the PRI of the measured signal, the sampling is ensured to be started when the antenna of the radiation source is opposite to the receiver, the antenna scanning is slow, and the sampling delay is the time required for pointing to the target monitoring area after the estimated maximum value is scanned through the receiver.
Claims (10)
1. Simple single-channel passive bistatic mine system is characterized in that: the system comprises an antenna module, a signal frequency conversion module, a signal acquisition processing module and a data processing display PC terminal;
the antenna module is used for receiving signals;
the signal frequency conversion module comprises a signal frequency conversion unit and a clock and local oscillator unit;
the frequency conversion unit is a single-channel receiver, receives signals of the antenna module, processes the signals and transmits the processed signals to the signal acquisition processing module, and simultaneously receives signals of the clock and the local oscillation unit;
the local oscillator unit receives signals of the signal acquisition and processing module and transmits the signals to the signal acquisition and processing module and the frequency conversion unit;
the signal acquisition processing module comprises a signal acquisition unit, a main control unit and an interface unit;
the acquisition unit receives signals of the frequency conversion unit, transmits the signals to the main control unit and the interface unit, and simultaneously receives signals of the interface unit, the clock and the local oscillation unit;
the interface unit transmits signals of the acquisition unit to the main control unit and the data processing display PC terminal, and transmits signals of the main control unit and the data processing display PC terminal to the acquisition unit;
the data processing display PC terminal realizes the control of the whole system and analyzes, processes and displays the acquired data.
2. The simple single-channel passive bistatic mine system of claim 1, wherein: the antenna module adopts a simple horn antenna, is a directional antenna, has the signal receiving capability of 1-2 GHz, and aims at an L-band warning radar irradiation source.
3. The simple single channel passive bistatic mine system of claim 1 or 2, wherein: the signal frequency conversion unit converts, amplifies and filters signals received by the antenna into intermediate frequency analog signals;
the clock and local oscillator unit generates various reference clock signals.
4. A simple single channel passive bistatic mine system according to claim 3, wherein: the signal frequency conversion module consists of an L-band field amplifier, an L-band frequency synthesizer and an L-band frequency converter.
5. The simple single channel passive bistatic mine system of claim 4, wherein: the L-band field amplifier is used for amplifying the L-band direct wave and target echo radio frequency signals received by the antenna; the L-band field amplifier comprises two filters, a limiter, and a low noise amplifier. Radio frequency input frequency: 1100 MHz-1400 MHz, gain: 15dB or more, noise coefficient: less than or equal to 3dB;
the L-band frequency synthesizer adopts a phase-locked loop to output a path of 1 local oscillator and a path of 2 local oscillators, wherein the 1 local oscillator outputs frequency: 1600 MHz-1900 MHz,1MHz steps, and the frequency is controlled; 2 local oscillation output frequency: 640MHz; local oscillator output level: not less than 0dBm;
the L-band double-channel frequency converter is used for receiving L-band signals and outputting intermediate frequency signals through frequency conversion, amplification and filtering.
6. The simple single channel passive bistatic mine system of claim 5, wherein: the acquisition unit converts an intermediate frequency analog signal which is processed by the signal frequency conversion unit and is mixed with the direct wave and the target echo into a baseband digital signal;
the main control unit calculates various commands and parameters and controls each module to work normally according to a set time sequence;
the interface unit adopts a PCIEx4 bus interface to realize external connection of the system.
7. The IQ data processing method of the simple single-channel passive bistatic mine system according to any one of claims 1 to 6, wherein: the method comprises the following steps:
1. single channel pulse compression
The pulse compression module performs simultaneous pulse compression processing on single-channel IQ data mixed with the direct wave and the target echo, and outputs compressed narrow pulse mixed with the direct wave and the target echo;
2. direct wave extraction and separation
When the first step is completed, according to the time domain characteristics, when the target is far away from the receiving and transmitting antenna or the pulse width of the pulse signal is narrow, the direct wave and the target echo signal can be separated in time, so that the direct wave and the target echo signal are separated by adopting a time window technology;
3. time synchronization processing
Extracting the separated direct wave signal by the second step, and extracting time synchronization information from the direct wave signal, wherein the time synchronization information comprises arrival time and pulse repetition interval information, and outputting pulse repetition interval trigger pulses synchronized with the direct wave after time synchronization processing;
4. direction synchronization processing
Extracting antenna azimuth synchronization information from the separated direct wave signals by utilizing the second step, forming a pulse peak value when a radar antenna sweeps a receiver, and utilizing the maximum peak value to complete azimuth synchronization and display data;
5. MTI and MTD moving object processing
Processing the MTI filter by adopting three pulses, and compensating the Doppler frequency of echo pulses before the MTI processing;
the MTD is achieved by FFT processing of pulses with multiple adjacent pulse repetition periods, which corresponds to coherent accumulation of echo bursts;
the main purpose of the moving object display (MTI) technology is to improve the detection capability of radar moving objects, filter out static objects and clutter and display the moving objects;
the main purpose of the moving object processing (MTD) technology is to obtain a range Doppler image (R-D image) of a moving object for data display;
6. video accumulation
Accumulating the envelope amplitudes of the echo signals with the video accumulated to 6-12 identical distance units;
7. constant false alarm detection
And adopting a unit average maximum selection constant false alarm detection (GO-CFAR) detector to perform target constant false alarm detection, reducing the false alarm rate and the false alarm rate, and performing data display in the form of difficult background power level estimation in the CFAR detection threshold forming process.
8. The simple single-channel passive bistatic mine system IQ data processing method of claim 7, wherein the method comprises the following steps of: the single channel pulse compression comprises the following two methods:
reconstructing a direct wave reference signal according to a known prior parameter or an estimated parameter, wherein the direct wave reference signal and an echo signal complete pulse compression;
and secondly, directly intercepting a section of complete direct wave sample signal in the IQ data, and completing pulse compression with the echo signal, which is equivalent to cross-correlation of the sample signal and the echo signal.
9. The simple single-channel passive bistatic mine system IQ data processing method of claim 8, wherein the method comprises the following steps of: the direct wave extraction and separation adopts the following steps: and extracting and separating the direct wave from single-channel IQ data mixed with the direct wave and the target echo by using the condition constraints such as the frequency, the pulse width, the amplitude, the Pulse Repetition Interval (PRI) and the phase difference of the direct wave.
10. The simple single-channel passive bistatic mine system IQ data processing method according to claim 9 wherein the method is characterized in that: the time synchronization processing method comprises the following steps: estimating the arrival time of each received pulse by thresholding the received signal after pulse compression and arrival time training has occurred; the pulse repetition interval uses the time difference between adjacent arrival times.
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