CN102053242A - Signal parameter real-time precision measurement method of synthetic aperture radar - Google Patents
Signal parameter real-time precision measurement method of synthetic aperture radar Download PDFInfo
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Abstract
The invention provides a signal parameter real-time precision measurement method of a synthetic aperture radar (SAR) and belongs to the field of radar signal detection. The method integrates the digital channelized receiver technique and the phase difference instantaneous frequency measurement technique to achieve the real-time parameter measurement of the signals of the SAR; in consideration of the processing capacity of the processor and the hardware resources, the parallel processing method and the hardware resource time division multiplexing method are integrated to achieve the real-time processing of the huge data stream generated by the signals of the high-bandwidth high-timewidth non-cooperative SAR in the prior processor; the inherent error of the system time parameter is analyzed by use of the laboratory environment and the time parameter is compensated; and the transient response is avoided by utilizing the characteristics of the SAR signals and the frequency-domain parameter is correctd to obtain the accurate frequency-domain parameter. The method reduces the computation load, provides full consideration, achieves the real-time precision measurement of the signal parameters of the high-bandwidth high-timewidth non-cooperative SAR, and improves the real-time property and the precision of processing the high-bandwidth high-timewidth signals of the detection receivers in service.
Description
Technical field
The present invention relates to a kind of synthetic aperture radar (SAR) signal parameter real-time accurate measuring method, belong to radar signal and scout the field.
Background technology
Synthetic-aperture radar is exactly to utilize the relative motion of radar and target the less real antenna aperture of size to be synthesized the radar in bigger antenna eliminator aperture with the method for data processing.For under the situation of not losing range resolution, increase investigative range, SAR adopts the linear FM signal with long-pending characteristic of wide bandwidth when big usually.By adopting linear FM signal, when SAR improves detectivity, also had low intercepting and capturing.In modern electronic warfare, wide, big bandwidth and the low property intercepted and captured during at SAR signal big propose a kind of method and noncooperative SAR signal is carried out accurate real-time parameter measurement have great importance.
At present, proposed the method for many analysis SAR signals both at home and abroad, mainly contained: Fourier conversion in short-term, Wigner-Ville time frequency analysis and time-frequency decomposition, wavelet transformation, Chirplet conversion, Fractional Fourier Transform, spectrum correlation analysis method, higher order statistical metering method and other signal processing methods etc.There is calculation of complex in these methods to non-cooperation SAR Signal Processing, do not possess real-time processing and precision measurement two-fold advantage.
Summary of the invention
The purpose of this invention is to provide a kind of synthetic-aperture radar signal parameter real-time accurate measuring method, with solve prior art be difficult to non-cooperation SAR signal parameter carry out in real time, the problem of precision measurement.
For achieving the above object, a kind of synthetic-aperture radar signal parameter of the present invention real-time accurate measuring method may further comprise the steps:
The first step:, determine Digital Down Convert coefficient and low-pass filter coefficients according to channel number and instant bandwidth according to frequency domain digital channelizing multiphase filtering principle;
Second step: the coefficient storage that the first step is obtained realizes frequency domain digital channelizing filtering at the scene in the programmable gate array in ROM (read-only memory);
The 3rd step: complex signal is carried out after the frequency domain digital channelizing multiphase filtering, adopt cordic algorithm to calculate each channel output result's amplitude and phase place;
The 4th step: obtain utilizing the phase differential point-score to calculate the instantaneous frequency of each channel signal after the phase place;
The 5th step: signal was carried out Threshold detection,, reject wrong channel, signal is incorporated in the correct channel according to the amplitude and the instantaneous frequency measurement information of signal;
The 6th step: according to SAR signal time-frequency characteristic, testing result is carried out data fusion, the initial moment of tracer signal, stop moment, initial frequency, termination frequency, wherein accurate frequency values two parts are formed in the channel that obtained by channel number frequency value corresponding and instantaneous frequency measurement of frequency values;
The 7th step: the signal calculated chirp rate, utilize chirp rate signal pulsewidth, initial frequency, termination frequency to be revised with under laboratory environment, using the time parameter error of determining the signal estimation, form the PDW of pulse describing word accurately.
Wherein realize that by multistage flowing water phase Calais the phase of a plurality of data is improved the processing speed of processor in the described implementation procedure of second step, adopt the position of the method deal with data addition of block floating point to increase simultaneously.
Above-mentioned method adopts the method for local channel parallel computation, channel hardware resource time-sharing multiplex to realize.
Advantage of the present invention is as follows:
1. wide non-cooperation SAR signal carried out real-time parameter and measures when this invention was can be to big bandwidth big
Method of the present invention adopts frequency domain digital channelizing polyphase filter technology to improve the signal Processing gain, and make full use of the time-frequency characteristic of SAR signal, measurement result to a plurality of channels is carried out data fusion, take into full account the processing power and the hardware resource of processor, propose the implementation method of " local channel parallel computation; resource time-sharing multiplex ", wide non-cooperation SAR signal carries out real-time parameter and measures when can be to big bandwidth big.
2. this invention can be carried out the real-time accurate measurement to non-cooperation SAR signal parameter
The mode that method of the present invention adopts frequency domain digital channelizing multiphase filtering to combine with the phase difference instantaneous frequency measurement obtains the frequency information of signal, bring measuring error in order to reduce FIR performance of filter and transient response, the time parameter statistical error of utilizing laboratory environment to obtain reaches the chirp rate that measures in real time signal parameter is calibrated, and has realized the real-time accurate of non-cooperation SAR signal parameter is measured.
The complex signal data that high speed acquisition obtains are carried out real-time frequency domain digital channelizing multiphase filtering; Adopt rotation of coordinate digital computation (CORDIC) algorithm to obtain filtering result's mould value and phase information; Utilize the phase differential point-score to calculate the instantaneous frequency value of each channel; Signal is carried out CFAR detection; According to the characteristic comprehensive detection result of SAR signal, obtain the bigness scale amount parameter of SAR signal and parameter compensated to form PDW accurately.
Description of drawings
Fig. 1-be method flow synoptic diagram of the present invention;
Fig. 2-be the implementation structure figure of complex signal frequency domain digital channelizing multiphase filtering;
Embodiment
Below in conjunction with accompanying drawing a kind of SAR signal parameter real-time accurate measuring method of the present invention is described in detail.
A kind of SAR signal parameter of the present invention real-time accurate measuring method, flow process as shown in Figure 1.The bandwidth of ultra broadband SAR signal is the GHz level, and this class signal is sampled, and analog to digital conversion speed must also be the Gsps level, but also is the I/Q sampling.The Fast Fourier Transform (FFT) of using in the channelizing filtering (FFT) realizes by base-4 butterfly computations, realizes that by multistage flowing water phase Calais the phase of a plurality of data is improved the adaptable processing speed of processor in the programmable gate array at the scene.Adopt the position growing concern of the method deal with data addition of block floating point in the processing, to obtain high-precision result.Complex signal is carried out adopting cordic algorithm to calculate each channel output result's amplitude and phase place after the frequency domain digital channelizing multiphase filtering.Obtain utilizing the phase differential point-score to calculate the instantaneous frequency of each channel signal after the phase place.Signal was carried out Threshold detection, and according to the amplitude and the instantaneous frequency measurement information of signal, the channel problem of striding of consequential signal incorporates signal in the correct channel into.For superfast data are carried out real time signal processing, realization design from channelizing filtering to input all is under the processing power of taking all factors into consideration processor and resource operating position, adopt the local channel parallel computation, the method for channel hardware resource time-sharing multiplex realizes.Like this processing power of processor and hardware resource have been got compromisely, in existing processor, easily realized.
Input is afterwards according to the distinctive time-frequency characteristic of SAR signal, signal should be exported from different channels successively in different time sections, and these channels are continuous uninterrupted, in view of the above testing result is carried out data fusion, the initial moment of tracer signal, stop moment, initial frequency, termination frequency, wherein accurate frequency values two parts are formed in the channel that obtained by channel number frequency value corresponding and instantaneous frequency measurement of frequency values.When using one group of FIR filter parameter for the first time, for fear of the performance of FIR wave filter to the initial moment of signal and stop the influence of judgement precision constantly, under laboratory environment, use definite signal to estimate this time parameter error earlier, be used for correction parameter measurements.Because there are the problem of transient response in initial, the final position of signal, according to the characteristics of SAR signal, initial, the not value of the number of winning the confidence edge of trying one's best when stopping the frequency value of signal.The signal calculated chirp rate, the time parameter inherent error of utilizing chirp rate and laboratory environment to obtain is revised signal pulsewidth, initial frequency, termination frequency, forms the PDW of pulse describing word accurately.
Present embodiment is at first determined the implementation structure of frequency domain digital channelizing multiphase filtering, as shown in Figure 2.The receiver of one 64 channel, be that D among Fig. 2 equals 64, when in FPGA, realizing, per 8 channels are classified as one group, a processing cycle is only handled 8 channels, 8 processing cycles are just intact with 64 Channel Processing, so just will trade off to the requirement of processing power and processing resource, satisfy the requirement to existing digital signal processor.Adopt water operation in the processing, the time-sharing multiplex resource only can cause result that 7 hysteresis of handling the cycle are arranged, and this does not influence the real-time generation of result.Adopt the amplitude and the phase place of the complex data of each channel output after the cordic algorithm calculation of filtered after the channelizing.Obtain after the phase place of complex data, adopt the method for phase difference instantaneous frequency measurement that each channel is carried out instantaneous frequency measurement, computing formula is as follows:
f(n)＝[φ(n)-φ(n-1)]*Fs/2π
Wherein φ is the complex data phase place, and Fs is the sampling rate of data correspondence in the channel, and π is a circular constant.
Data behind the instantaneous frequency measurement are carried out the amplitude CFAR cross the channel problem of striding that Threshold detection judges simultaneously that also the instantaneous frequency information of respective channel output exists with the solution broadband signal, signal begins to occur from channel (K), T (0) is the initial moment of signal constantly, writes down the time value T0 in this moment; Signal occurred after L1 processing cycle, and T (1) frequency values and time value constantly is designated as F1 and T1 respectively; T (3) constantly detects signal ended, and the time value of this moment is designated as T3, with T (3) before frequency values and the time value during L2 processing period T (2) be designated as F2 and T2 respectively.Choosing according to the concrete SAR of scouting signal pulsewidth parameter situation of L1 and L2 is fixed, thereby choosing the time value that too conference makes L1 add L2 causes makeing mistakes greater than the signal pulsewidth, thereby choose the too little transient response fall flat of not avoiding, L1 and L2 are respectively 16 and 24 in the present embodiment.
During one group of filter parameter of first use, under laboratory environment, utilize definite signal to estimate the inherent variability Delt0 of T0 and the inherent variability Delt3 of T3.
Next be that parameter is compensated.At first be time of arrival (toa) TOA and signal ended time T OE
TOA＝T0-Delt0
TOE＝T3+Delt3
The difference of the TOA of a TOA and a last signal is exactly the repetition period PRI of signal, and TOE-TOA is exactly the pulse width PW of signal.
According to the signal parameter T1, the T2 that record, F1, F2 by formula
K＝(F2-F1)/(T2-T1)
Obtain the chirp rate K of signal.
According to formula
Fstart＝F1-K*(L1+Delt0)
Fstop＝F2+K*(L2+Delt3)
Initial frequency and termination frequency are compensated, obtain final initial frequency Fstart and stop frequency Fstop.
According to formula
BW＝Fstop-Fstart
Promptly obtain the bandwidth BW of signal.
SAR signal parameter real-time accurate measuring method of the present invention makes full use of the time-frequency characteristic of SAR signal, avoids the transient response problem of signal Processing, the accurate parameter that obtains being scouted signal.The phase difference instantaneous frequency measurement carries out after the channelizing of complex signal frequency domain digital, has reduced the requirement to the raw data signal to noise ratio (S/N ratio), makes the entire process algorithm can obtain the parameter of non-accurately cooperation SAR signal in real time under lower signal to noise ratio (S/N ratio).
Claims (3)
1. synthetic-aperture radar signal parameter real-time accurate measuring method is characterized in that: may further comprise the steps:
The first step:, determine Digital Down Convert coefficient and low-pass filter coefficients according to channel number and instant bandwidth according to frequency domain digital channelizing multiphase filtering principle;
Second step: the coefficient storage that the first step is obtained realizes frequency domain digital channelizing filtering at the scene in the programmable gate array in ROM (read-only memory);
The 3rd step: complex signal is carried out after the frequency domain digital channelizing multiphase filtering, adopt cordic algorithm to calculate each channel output result's amplitude and phase place;
The 4th step: obtain utilizing the phase differential point-score to calculate the instantaneous frequency of each channel signal after the phase place;
The 5th step: signal was carried out Threshold detection,, reject wrong channel, signal is incorporated in the correct channel according to the amplitude and the instantaneous frequency measurement information of signal;
The 6th step: according to SAR signal time-frequency characteristic, testing result is carried out data fusion, the initial moment of tracer signal, stop moment, initial frequency, termination frequency, wherein accurate frequency values two parts are formed in the channel that obtained by channel number frequency value corresponding and instantaneous frequency measurement of frequency values;
The 7th step: the signal calculated chirp rate, utilize chirp rate signal pulsewidth, initial frequency, termination frequency to be revised with under laboratory environment, using the time parameter error of determining the signal estimation, form the PDW of pulse describing word accurately.
2. a kind of synthetic-aperture radar signal parameter real-time accurate measuring method according to claim 1, it is characterized in that: wherein realize that by multistage flowing water phase Calais the phase of a plurality of data is improved the processing speed of processor in the described implementation procedure of second step, adopt the position of the method deal with data addition of block floating point to increase simultaneously.
3. a kind of synthetic-aperture radar signal parameter real-time accurate measuring method according to claim 1 and 2 is characterized in that: above-mentioned method adopts the method for local channel parallel computation, channel hardware resource time-sharing multiplex to realize.
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| CN102739272A (en) * | 2012-06-26 | 2012-10-17 | 哈尔滨工程大学 | Channelized receiver sub-channel real-time frequency spectrum synthesis method based on field programmable gate array (FPGA) |
| CN103813307A (en) * | 2012-11-13 | 2014-05-21 | 中兴通讯股份有限公司 | False channel request filtering method and device |
| CN104656067A (en) * | 2013-11-25 | 2015-05-27 | 北京环境特性研究所 | Frequency modulation slop estimation method based on picture contrast |
| CN108363076A (en) * | 2018-01-16 | 2018-08-03 | 北京理工大学 | A kind of human interference instantaneous Frequency Estimation system and method based on Renyi entropys in short-term |
| CN112014810A (en) * | 2020-08-07 | 2020-12-01 | 西安电子科技大学 | Electronic reconnaissance signal parameter high-precision measurement method based on FPGA |
| CN112596087A (en) * | 2021-03-04 | 2021-04-02 | 长沙海格北斗信息技术有限公司 | FIR digital filtering method for satellite navigation, navigation chip and receiver |
| CN116736680A (en) * | 2023-08-16 | 2023-09-12 | 中国科学技术大学 | High-precision time information extraction method for band-pass signals |
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| CN102739272A (en) * | 2012-06-26 | 2012-10-17 | 哈尔滨工程大学 | Channelized receiver sub-channel real-time frequency spectrum synthesis method based on field programmable gate array (FPGA) |
| CN102739272B (en) * | 2012-06-26 | 2014-08-20 | 哈尔滨工程大学 | Channelized receiver sub-channel real-time frequency spectrum synthesis method based on field programmable gate array (FPGA) |
| CN103813307A (en) * | 2012-11-13 | 2014-05-21 | 中兴通讯股份有限公司 | False channel request filtering method and device |
| WO2014075501A1 (en) * | 2012-11-13 | 2014-05-22 | 中兴通讯股份有限公司 | Method and device for filtering false channel request |
| CN103813307B (en) * | 2012-11-13 | 2017-12-08 | 中兴通讯股份有限公司 | The method and apparatus for filtering wrong channel request |
| CN104656067A (en) * | 2013-11-25 | 2015-05-27 | 北京环境特性研究所 | Frequency modulation slop estimation method based on picture contrast |
| CN108363076A (en) * | 2018-01-16 | 2018-08-03 | 北京理工大学 | A kind of human interference instantaneous Frequency Estimation system and method based on Renyi entropys in short-term |
| CN108363076B (en) * | 2018-01-16 | 2021-09-10 | 北京理工大学 | System and method for estimating instantaneous frequency of man-made interference based on short-time Renyi entropy |
| CN112014810A (en) * | 2020-08-07 | 2020-12-01 | 西安电子科技大学 | Electronic reconnaissance signal parameter high-precision measurement method based on FPGA |
| CN112014810B (en) * | 2020-08-07 | 2024-04-05 | 西安电子科技大学 | High-precision electronic reconnaissance signal parameter measurement method based on FPGA |
| CN112596087A (en) * | 2021-03-04 | 2021-04-02 | 长沙海格北斗信息技术有限公司 | FIR digital filtering method for satellite navigation, navigation chip and receiver |
| CN112596087B (en) * | 2021-03-04 | 2022-04-08 | 长沙海格北斗信息技术有限公司 | FIR digital filtering method for satellite navigation, navigation chip and receiver |
| CN116736680A (en) * | 2023-08-16 | 2023-09-12 | 中国科学技术大学 | High-precision time information extraction method for band-pass signals |
| CN116736680B (en) * | 2023-08-16 | 2023-11-28 | 中国科学技术大学 | High-precision time information extraction method for band-pass signals |
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Application publication date: 20110511 |