CN117724035A - Interferometer direction finding positioning method based on two-stage correction - Google Patents
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Abstract
The invention discloses a two-stage correction-based interferometer direction-finding positioning method, which belongs to the technical field of radars. Firstly, a receiving channel processes signals received by an antenna, and the initial phases of the received signals reaching different antennas are obtained through AD sampling, FFT and other processing, and then the path difference generated by a long cable is corrected in real time; the phase difference after phase correction contains angle information, the direction cosine of the signal is estimated by a least square method by utilizing the measured phase difference, and the angle information of the pulse is obtained; finally, carrying out least square iterative positioning calculation by using the direction finding information to obtain the position information estimation of the target signal; and finally, calibrating the measurement estimation result by using the prior information of the correction system, and further improving the performance of system direction finding and positioning.
Description
Technical Field
The invention belongs to the technical field of radars, and particularly relates to a direction-finding and positioning method of an interferometer based on two-stage correction.
Background
In modern signal processing, how to accurately estimate the ground target position through signal detection and parameter measurement and estimation is important content of target identification, spectrum sensing and remote sensing. The space detection technology has the advantages of all weather, all day, wide coverage range and high precision, and is a powerful means for acquiring information. With the rapid development of spatial detection technology in recent years, the spatial detection technology has become an indispensable part of digital signal processing.
In order to accurately estimate the signal direction, the radar technology field usually adopts a multi-baseline interferometer to perform direction finding and positioning, the multi-baseline interferometer adopts a configuration with long and short baselines to realize high-precision direction finding and positioning, at the moment, the length of a cable is long and is easily influenced by environmental factors such as temperature, so that the signals generate path differences in different long cables, the phase difference measurement error is increased, the positioning precision of the interferometer direction finding and positioning system is seriously influenced, and the detection capability of the system is reduced; meanwhile, the working environment of the actual radar system is complex and changeable, and various non-Gaussian and broadband noise interference signals inevitably exist in the detection electromagnetic frequency range, and the detection performance of the target radiation source is seriously influenced due to errors caused by the systematic errors of the radar system, electromagnetic propagation and the like. In this regard, based on the system of the common multi-baseline interferometer, the method for effectively reducing the system measurement error is researched, and has important significance for improving the detection performance of the radar.
Disclosure of Invention
The invention provides a two-stage correction-based interferometer direction-finding positioning method, which realizes high-precision estimation of phase difference, greatly reduces the influence caused by parameter measurement errors and improves the precision of interferometer phase difference estimation.
The technical scheme for realizing the invention is as follows: an interferometer direction finding positioning method based on two-stage correction comprises the following steps:
step 1, AD sampling is firstly carried out on radar signals, then channelized detection is carried out, signal pulse sequences of all channels are obtained, and step 2 is carried out.
And 2, performing FFT (Fast Fourier Transformation, fast Fourier transform) on signals in signal pulse sequences of different channels respectively to obtain frequency domain parameters of the signals, obtaining initial phase values of the signals by utilizing the frequency domain parameters, and subtracting the initial phase values of all the channels to obtain phase differences among multiple channels so as to obtain original full pulses with phase difference information, and turning to step 3.
Step 3, generating a correction signal of a full frequency band in the working frequency band by using a self-checking calibration source, and according to the frequency point of the current signal in the original full pulseCorrecting phase error introduced by cable and frequency conversion device in real timeAnd (4) obtaining corrected full pulse, and turning to step 4.
And 4, carrying out direction finding and defuzzification by utilizing a least square defuzzification method according to the corrected phase difference information in the full pulse to obtain the direction cosine of the signal in the full pulse after direction finding, obtaining pulse angle information, and turning to the step 5.
And 5, carrying out signal sorting on the full pulse after the measurement to obtain a radiation source, carrying out on-line correction on the system error according to the frequency point, the channel and the antenna by using the prior calibration information of the correction system to obtain a corrected directional cosine, further obtaining the radiation source with the corrected directional cosine angle, and turning to the step 6.
Step 6, positioning and calculating the corrected radiation source, and assuming that the distance between the target and the receiver is thatPosition of the radiation source，For transferring rotation matrix from the geodetic coordinate system to the platform coordinate system, the cosine of the direction of the arrival angle of the signal is usedAndcombining the position of receivers in the earth's coordinate systemThe radiation source position is resolved.
Compared with the prior art, the invention has the remarkable advantages that:
1) According to the phase difference real-time correction method, the high-precision phase difference measurement of the long baseline interferometer is realized, and the adaptability to complex environments is improved.
2) The invention provides a method for carrying out two-dimensional direction-finding positioning based on least square iterative computation, which further improves the estimation accuracy of direction-finding positioning.
3) The invention provides a method for introducing a correction system, which realizes the calibration of an error model by using priori information, effectively corrects the system error in an electromagnetic environment, improves the direction-finding positioning performance index and increases the accuracy of acquiring target information.
Drawings
FIG. 1 is a flow chart of a two-stage correction-based interferometer direction finding and positioning method of the present invention.
Fig. 2 is a schematic diagram of the relationship between the direction-finding positioning error and the angle error according to the present invention.
Fig. 3 is a graph of angular positioning error Geometry (GDOP) of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by one of ordinary skill in the art without creative efforts, are within the scope of the present invention based on the embodiments of the present invention.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to base that the technical solutions can be implemented by those skilled in the art, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered to be absent, and not included in the scope of protection claimed in the present invention.
The following describes the specific embodiments, technical difficulties and inventions of the present invention in further detail in connection with the present design examples.
Referring to fig. 1, the method for positioning the interferometer direction-finding based on the two-stage correction comprises the following steps:
and step 1, carrying out AD sampling on the radar signals, then carrying out channelized detection to obtain signal pulse sequences of all channels, and turning to step 2.
And 2, performing FFT on signals of signal pulse sequences of different channels respectively to obtain frequency domain parameters of the signals, measuring the frequency domain parameters to obtain initial phase values of the signals, and subtracting the initial phase values of all the channels to obtain phase differences among multiple channels so as to obtain original full pulses with phase difference information. The phase value of the signal can be obtained quickly by carrying out FFT on the signal, the engineering implementation is simple, and the calculated amount is small.
And (3) switching to step 3.
Step 3, generating a correction signal of a full frequency band in the working frequency band by using a self-checking calibration source, and according to the frequency point of the current signal in the original full pulseCorrecting phase error introduced by cable and frequency conversion device in real timeThe corrected full pulse is obtained, and specifically comprises the following steps:
step 31, using the self-checking calibration source to measure the phase difference of the calibration source correction signals for the channel A and the channel B in real timeMeasuring the channel phase difference after the pre-amplifying filter moduleBy means ofAndthe two groups of phase difference calculation are used for obtaining the real-time phase difference of the long cable between the pre-amplifying filter module and the microwave frequency conversion calibration source。
Step 32, calculating the real-time phase difference of the long cable according to the step 31Fixed phase difference between different channelsAbsolute phase difference of pre-amplification modulePerforming phase difference correction, and calculating true phase difference between corrected channels A, BThe specific calculation expression is:
，
step 33, correcting the phase difference among all channels according to the step 32, and inputting the corrected phase difference information into the full pulse to obtain a corrected full pulse.
The multi-baseline interferometer adopts the configuration of long and short baselines to realize high-precision direction finding and positioning, and because the length of the cable is long and is easily influenced by environmental factors such as temperature, the long cable introduces phase difference into the system, phase difference measurement error is increased, positioning precision of the next stage is seriously influenced, and the detection capability of the system is reduced.
And (4) switching to step 4.
And 4, carrying out direction finding and defuzzification by utilizing a least square defuzzification method according to the corrected phase difference information in the full pulse to obtain the direction cosine of the signal in the full pulse after direction finding, obtaining pulse angle information, and turning to the step 5.
Step 5, sorting the measured full pulse to obtain a radiation source, carrying out on-line correction on the system error according to the frequency point, the channel and the antenna by using the prior calibration information of the correction system to obtain a corrected directional cosine, and further obtaining the radiation source with the corrected directional cosine angle, and specifically comprising the following steps:
and 51, sorting the full pulse after the measurement to obtain a sorted radiation source.
Step 52, transmitting known cooperative signals of a plurality of frequency points by using a plurality of correction systems, receiving and constructing a priori error correction parameter matrix through an antenna, calling error correction parameters according to the frequency points and channels for the actually received sorted radiation sources, correcting phase differences generated by system errors, antenna position errors and the like, obtaining corrected directional cosine, and further obtaining the radiation sources with direction cosine angle correction.
The invention creatively provides a method for introducing a correction system, which utilizes ground calibration to generate cooperative signals to build a calibration error model, utilizes priori information to effectively correct the system errors in electromagnetic environment, improves positioning performance indexes and increases the accuracy of acquiring target information.
Go to step 6.
Step 6, positioning and resolving the corrected radiation source angle information, and assuming that the distance between the target and the receiver isPosition of the radiation source，For transferring rotation matrix from the geodetic coordinate system to the platform coordinate system, the cosine of the direction of the arrival angle of the signal is usedAndcombining the position of receivers in the earth's coordinate systemThe method comprises the following steps of:
step 61, constructing a radiation source positioning solution equation, wherein the expression is as follows:
，
in which the direction cosine，For transferring rotation matrix from the attitude of the earth coordinate system to the platform coordinate system, the position of the receiver under the earth coordinate system。
And step 62, calculating a Jacobian matrix and a residual error by using a nonlinear least square estimation method according to the initial position value obtained by the positioning calculation, and obtaining a radiation source position result by using phase information iterative estimation in the radiation source.
After experimental analysis of measured data, as shown in fig. 2 and 3, the positioning accuracy meets 4km in a range of 1000km radius below the receiver and approaches to CRLB (cramer-Rao low bound, caramet-ro lower limit) under the condition that the angle measurement error is considered to be within a certain range after two-stage correction.
Claims (4)
1. The interferometer direction finding positioning method based on the two-stage correction is characterized by comprising the following steps of:
step 1, AD sampling is firstly carried out on radar signals, then channelized detection is carried out, signal pulse sequences of all channels are obtained, and step 2 is carried out;
step 2, performing FFT on signals in signal pulse sequences of different channels respectively to obtain frequency domain parameters of the signals, obtaining initial phase values of the signals by utilizing the frequency domain parameters, and subtracting the initial phase values of all the channels to obtain phase differences among multiple channels so as to obtain original full pulses with phase difference information, and turning to step 3;
step 3, generating a correction signal of a full frequency band in the working frequency band by using a self-checking calibration source, and according to the frequency point of the current signal in the original full pulseCorrecting phase error introduced by cable and frequency conversion device in real time>Obtaining corrected full pulse, and transferring to step 4;
step 4, according to the phase difference information in the corrected full pulse, using a least square solution blurring method to perform direction finding and blurring to obtain the direction cosine of the signal in the full pulse after direction finding, obtaining pulse angle information, and turning to step 5;
step 5, carrying out signal sorting on the full pulse after the measurement to obtain a radiation source, carrying out online correction on the system error according to the frequency point, the channel and the antenna by utilizing the prior calibration information of the correction system to obtain a corrected directional cosine, further obtaining the radiation source with the corrected directional cosine angle, and turning to step 6;
step 6, positioning and calculating the corrected radiation source, and assuming that the distance between the target and the receiver is thatPosition of the radiation source->，/>For transferring rotation matrix from the geodetic coordinate system to the platform coordinate system, the cosine of the direction of the arrival angle of the signal is usedAnd->Position of receiver under combined geodetic coordinate system +.>And calculating the position of the radiation source, wherein the calculation expression is as follows:
，
wherein the direction cosine。
2. The two-stage correction-based interferometer direction finding positioning method according to claim 1, wherein in step 3, a self-checking calibration source is used to generate a full-band correction signal in an operating band, and the correction signal is based on the frequency point of the current signalCorrecting phase error introduced by cable and frequency conversion device in real time>The corrected full pulse is obtained, and specifically comprises the following steps:
step 31, two channels are provided, namely a channel A and a channel B, and the self-checking calibration source is utilized to measure the phase difference of the calibration source correction signals of the channel A and the channel B in real timeMeasuring the channel phase difference after the pre-amplifying filter module>Utilize->And->The two groups of phase difference calculation are used for obtaining the real-time phase difference of a long cable between the pre-amplification filter module and the microwave frequency conversion calibration source>；
Step 32, according to the real-time phase difference of the long cableFixed phase difference between different channels +.>Absolute phase difference of pre-amplifier module>Performing phase difference correction to obtain the true phase difference between corrected channels A, BThe specific calculation expression is:
，
step 33, correcting the phase difference among all channels according to the step 32, and inputting the corrected phase difference information into the full pulse to obtain a corrected full pulse.
3. The interferometer direction-finding positioning method based on two-stage correction according to claim 2, wherein in step 5, signal sorting is performed on the full pulse after the direction finding to obtain a radiation source, and the prior information of the correction system is utilized to perform on-line correction on the system error according to the frequency point, the channel and the antenna to obtain a corrected direction cosine, and the method specifically comprises the following steps:
step 51, sorting the full pulse after the measurement to obtain a radiation source;
step 52, transmitting known cooperative signals of a plurality of frequency points by using a plurality of correction systems, receiving and constructing a priori error correction parameter matrix through an antenna, calling error correction parameters for the actually received sorted radiation sources according to the frequency points and channels, correcting phase differences generated by system errors and antenna position errors, and obtaining corrected directional cosine.
4. The two-stage correction-based interferometer direction finding positioning method of claim 3, wherein in step 6, the corrected radiation source is subjected to a positioning solution assuming a target distance from the receiver ofPosition of the radiation source->，/>For transferring the rotation matrix from the geodetic coordinate system to the platform coordinate system, the direction cosine of the signal arrival angle is utilized>And->Position of receiver under combined geodetic coordinate system +.>The position of the radiation source is obtained through calculation, and the method specifically comprises the following steps of:
step 61, constructing a radiation source positioning solution equation, wherein the expression is as follows:
，
in the method, in the process of the invention,，/>for the attitude transfer rotation matrix from the geodetic coordinate system to the platform coordinate system, the position of the receiver under the geodetic coordinate system +.>；
And step 62, calculating a Jacobian matrix and residual errors by using a nonlinear least square estimation method according to the initial position value obtained by the positioning calculation, and obtaining the position of the radiation source by using phase information in the radiation source through iterative estimation.
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