CN108983188A - A kind of search and track method of the radar return based on interference imaging altimeter - Google Patents

A kind of search and track method of the radar return based on interference imaging altimeter Download PDF

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Publication number
CN108983188A
CN108983188A CN201810778659.8A CN201810778659A CN108983188A CN 108983188 A CN108983188 A CN 108983188A CN 201810778659 A CN201810778659 A CN 201810778659A CN 108983188 A CN108983188 A CN 108983188A
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echo
search
interference imaging
noise
subpattern
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CN108983188B (en
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石晓进
翟文帅
杨杰芳
张云华
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National Space Science Center of CAS
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National Space Science Center of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/882—Radar or analogous systems specially adapted for specific applications for altimeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9023—SAR image post-processing techniques combined with interferometric techniques

Abstract

The invention discloses a kind of search and track methods of radar return based on interference imaging altimeter, the described method includes: step 1) interference imaging altimeter enters noise testing subpattern: the acquisition system noise at different AGC calculates the equivalent amplitude of system noise under all AGC；Step 2) interference imaging altimeter enters echo search subpattern: setting sample range, and sample window is mobile in sample range to carry out echo search；For step 3) after searching radar return, interference imaging altimeter is transferred to impulse cluster measurement subpattern: being adjusted using high pulse repetition frequency to sample window, then carries out echo tracking.Method of the invention passes through three operating submodes of design, it realizes the measurement of interference imaging altimeter system noise, the function that a wide range of echo search and echo finely track, meets the requirement of interference imaging altimeter accurate search and track radar echo-signal under high pulse repetition frequency.

Description

A kind of search and track method of the radar return based on interference imaging altimeter
Technical field
The present invention relates to radar altimeter technical field more particularly to a kind of radar returns based on interference imaging altimeter Search and track method.
Background technique
Interference imaging altimeter is a kind of New Type Radar altimeter, surveys high new skill using short baseline, low-angle interference Art system.Relative to conventional radar altimeter, interference imaging altimeter uses synthetic aperture technique and novel height tracing skill Art realizes the high-acruracy survey of sea level height, and has the advantages that wide swath and imageable.But due to interference imaging altimeter It needs to carry out orientation synthetic aperture, so the pulse recurrence frequency of interference imaging altimeter is much higher than conventional radar altimeter. The needs of working normally to meet interference imaging altimeter under high pulse repetition frequency and stablize search echo-signal, needs Design of operating modes is carried out according to its specific feature.Currently, Heavenly Palace two three-dimensional imaging microwave altimeters mounted are in the world On demonstrate the working mechanism of interference imaging altimeter for the first time.
Summary of the invention
It is an object of the present invention to be directed to the job requirement and feature of interference imaging altimeter, provide a kind of based on interference The search and track method of the radar return of imaging radar altimeter can satisfy interference imaging altimeter and catch under high pulse repetition frequency Obtain the requirement of tracking radar echo.
To achieve the goals above, the present invention provides a kind of search of radar return based on interference imaging altimeter with Track method, which comprises
Step 1) interference imaging altimeter enters noise testing subpattern: the acquisition system noise at different AGC, calculates The equivalent amplitude of system noise under all AGC；
Step 2) interference imaging altimeter enters echo search subpattern: setting sample range, sample window is in sample range Interior mobile progress echo search；
For step 3) after searching radar return, interference imaging altimeter is transferred to impulse cluster measurement subpattern: using high arteries and veins It rushes repetition rate to be adjusted sample window, then carries out echo tracking.
As a kind of improvement of the above method, the step 1) specifically: the interference imaging altimeter does not emit radar Signal, the acquisition system noise at different AGC, the then equivalent amplitude A of noisenoiseAre as follows:
Wherein, AnoiseFor noise equivalent amplitude, N is sampling number in sample window, xnFor the range value of n-th of sampled point； Record the equivalent amplitude of system noise under all AGC.
As a kind of improvement of the above method, the step 2) further comprises:
Step 2-1) according to satellite position calculation radar return time delay initial ranging value Td:
Wherein, X, Y, Z are satellite position, and c is the light velocity, REFor earth radius；
Step 2-2) setting echo search range delta T, sample window is in (Td-ΔT,Td+ Δ T) it moves and searches for back in range Wave；
Step 2-3) calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, If A > SAnoise, S is the customized factor, then judgement searches echo, and records radar return time delay T at this time；
Step 2-4) when continuous 2 times echo is searched, be transferred to step 3), otherwise, be transferred to step 2-2).
As a kind of improvement of the above method, the echo search range delta T meets: Δ T < Ts/2；Wherein, TsFor echo Search for the subpattern pulse repetition period.
As a kind of improvement of the above method, the step 3) further comprises:
Step 3-1) after searching radar return, interference imaging altimeter is transferred to impulse cluster measurement subpattern；Calculate thunder Up to the interval pulse number N emitted between reception signalburstSubpattern subpulse repetition period PRT is measured with impulse clusterbAre as follows:
Nburst=floor (T/Tbmin) (3)
PRTb=T/Nburst (4)
Wherein, floor, which is represented, is rounded downwards；T is radar return time delay when searching echo in step 2), TbminFor arteries and veins Rush the minimum pulse cluster repetition period under cluster measurement subpattern；
Step 3-2) according to the N of calculatingburstAnd PRTbParameter, adjustment interference imaging altimeter measure subpattern in impulse cluster Under pulse recurrence frequency and transmitting and receiving signal between be delayed, echo is scanned for；
Step 3-3) echo center of gravity G in sample window is calculated, adjustment sampling window position makes echo be in sample window center of gravity, Echo is tracked；
Step 3-4) calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, If A < SAnoise, then judge not search echo；
Step 3-5) do not search echo continuous 2 times, then judge that echo position is incorrect, is transferred to step 2).
The present invention has the advantages that
The present invention passes through three operating submodes of design: noise testing subpattern, echo search subpattern and impulse cluster are surveyed Quantum mode realizes the measurement of interference imaging altimeter system noise, the function that a wide range of echo search and echo finely track, Meet the requirement of interference imaging altimeter accurate search and track radar echo-signal under high pulse repetition frequency.
Detailed description of the invention
Fig. 1 is the flow chart of the search and track method of the radar return of the invention based on interference imaging altimeter；
Fig. 2 is noise testing subpattern time diagram of the invention；
Fig. 3 is echo search subpattern time diagram of the invention；
Fig. 4 is that impulse cluster of the invention measures subpattern time diagram.
Specific embodiment
Now in conjunction with attached drawing, the invention will be further described.
As shown in Figure 1, the present invention provides a kind of search and track methods of radar return based on interference imaging altimeter.
Interference imaging altimeter operating mode designed by the present invention can be described as by noise testing subpattern, echo search Subpattern, impulse cluster measure the operating mode of subpattern composition, specifically include:
Step 1): interference imaging altimeter, which initially enters, adopts noise subpattern, does not emit radar signal, an acquisition system is made an uproar Sound, as shown in Figure 2.Since system noise amplitude is related with receiver AGC (programme-controlled gain), so needing to calculate and record all Noise equivalent amplitude A under AGCnoise.Equivalent amplitude calculation formula is shown below.
Wherein A is equivalent amplitude, and N is sampling number in sample window, xnFor the range value of n-th of sampled point.
Step 2): after the equivalent amplitude of system noise under all AGC that recorded, interference imaging altimeter enters echo Subpattern is searched for, as shown in Figure 3.Firstly the need of according to the satellite position calculation radar return time delay T in GPS parameterd, expression formula Are as follows:
Wherein X, Y, Z are the satellite position that GPS is obtained, and c is the light velocity, REFor earth radius.
Step 3): setting echo search range delta T, sample window is in (Td-ΔT,Td+ Δ T) it moves and searches for back in range Wave, if the echo search subpattern pulse repetition period is Ts, then T is requireds2 Δ T of >.
Step 4): calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, if A > SAnoise, then judgement searches echo.Wherein S is the customized factor, represents the expection to system signal noise ratio, i.e. sample window When the interior equivalent amplitude of echo is greater than S times of system noise equivalent amplitude, judge echo at this time as useful signal.
Step 5): since radar echo signal intensity will receive earth's surface landform, the influence of the external conditions such as sexual intercourse, echo letter It number not necessarily keeps stablizing.If appearing in (Td-ΔT,Td+ Δ T) abnormal conditions of echo are not searched in range, should again into Row search, searches echo only continuous 2 times, could judge that stabilization searches echo and is transferred to impulse cluster measurement subpattern.
Step 6): it after being transferred to impulse cluster measurement subpattern, needs to calculate impulse cluster measurement according to radar return time delay The interval pulse number of mode and subpulse repetition period, as shown in Figure 4.If under echo search subpattern, stabilization searches echo When, radar return time delay is T, and the minimum pulse cluster repetition period is T under impulse cluster measurement subpatternbmin, then radar emission with connect Interval pulse number N between the collection of letters numberburstSubpattern subpulse repetition period PRT is measured with impulse clusterbIt can indicate are as follows:
Nburst=floor (T/Tbmin) (3)
PRTb=T/Nburst (4)
Wherein floor, which is represented, is rounded downwards.
According to the N of calculatingburstAnd PRTbParameter, adjustment interference imaging altimeter measure the pulse under subpattern in impulse cluster It is delayed between repetition rate and transmitting and receiving signal, guarantees to search radar return with high pulse repetition frequency；
Step 7): calculating echo center of gravity G in sample window, and fine tuning sampling window position is in echo at sampling window center.It returns The formula of wave center of gravity G is as follows:
Wherein N is sampling number in sample window, xnFor the range value of n-th of sampled point.
Step 8): calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, if A < SAnoise, then judge not search echo, if occurring abnormal, do not search echo continuous 2 times, then judge echo position not Correctly, it should be transferred to echo search subpattern, re-search for echo.
The present invention has been successfully applied in No. two interference imaging altimeter projects of Heavenly Palace.In the project, noise testing Mode measures 128 AGC values of system one by one, and records the noise equivalent amplitude under each AGC.Echo search subpattern arteries and veins Rushing repetition rate is 1000Hz-1300Hz, and sample window can be in a wide range of interior carry out echo search of 500us.Impulse cluster submodule Formula pulse recurrence frequency is 15500Hz-16000Hz, and sample window is finely adjusted in the range of 2us, tracks to echo.? Appearance abnormal conditions, such as target backscattering coefficient are lower, and echo signal-to-noise ratio is low, cause to fail normal searching or tracking last time When wave, system can correctly carry out operating submode switching, reenter echo search subpattern search echo.
It should be noted last that the above examples are only used to illustrate the technical scheme of the present invention and are not limiting.Although ginseng It is described the invention in detail according to embodiment, those skilled in the art should understand that, to technical side of the invention Case is modified or replaced equivalently, and without departure from the spirit and scope of technical solution of the present invention, should all be covered in the present invention Scope of the claims in.

Claims (5)

1. a kind of search and track method of the radar return based on interference imaging altimeter, which comprises
Step 1) interference imaging altimeter enters noise testing subpattern: the acquisition system noise at different AGC, calculates all The equivalent amplitude of system noise under AGC；
Step 2) interference imaging altimeter enters echo search subpattern: setting sample range, sample window move in sample range It is dynamic to carry out echo search；
Step 3) is after searching radar return, and interference imaging altimeter is transferred to impulse cluster measurement subpattern: using high impulse weight Complex frequency is adjusted sample window, then carries out echo tracking.
2. the search and track method of the radar return according to claim 1 based on interference imaging altimeter, feature exist In the step 1) specifically: the interference imaging altimeter does not emit radar signal, and acquisition system is made an uproar at different AGC Sound, the then equivalent amplitude A of noisenoiseAre as follows:
Wherein, AnoiseFor noise equivalent amplitude, N is sampling number in sample window, xnFor the range value of n-th of sampled point；Record The equivalent amplitude of system noise under all AGC.
3. the search and track method of the radar return according to claim 2 based on interference imaging altimeter, feature exist In the step 2) further comprises:
Step 2-1) according to satellite position calculation radar return time delay initial ranging value Td:
Wherein, X, Y, Z are satellite position, and c is the light velocity, REFor earth radius；
Step 2-2) setting echo search range delta T, sample window is in (Td-ΔT,Td+ Δ T) it moves in range and searches for echo；
Step 2-3) calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, if A > S·Anoise, S is the customized factor, then judgement searches echo, and records radar return time delay T at this time；
Step 2-4) when continuous 2 times echo is searched, be transferred to step 3), otherwise, be transferred to step 2-2).
4. the search and track method of the radar return according to claim 3 based on interference imaging altimeter, feature exist In the echo search range delta T meets: Δ T < Ts/2；Wherein, TsFor the echo search subpattern pulse repetition period.
5. interference imaging altimeter design of operating modes method according to claim 4, which is characterized in that the step 3) Further comprise:
Step 3-1) after searching radar return, interference imaging altimeter is transferred to impulse cluster measurement subpattern；Calculate radar hair Penetrate and receive the interval pulse number N between signalburstSubpattern subpulse repetition period PRT is measured with impulse clusterbAre as follows:
Nburst=floor (T/Tbmin) (3)
PRTb=T/Nburst (4)
Wherein, floor, which is represented, is rounded downwards；T is radar return time delay when searching echo in step 2), TbminFor impulse cluster Measure the minimum pulse cluster repetition period under subpattern；
Step 3-2) according to the N of calculatingburstAnd PRTbParameter, adjustment interference imaging altimeter measure under subpattern in impulse cluster It is delayed between pulse recurrence frequency and transmitting and receiving signal, echo is scanned for；
Step 3-3) calculate sample window in echo center of gravity G, adjustment sampling window position, so that echo be in sample window center of gravity, to time Wave is tracked；
Step 3-4) calculate sample window in echo data equivalent amplitude A, and with the A under identical AGCnoiseIt is compared, if A < S·Anoise, then judge not search echo；
Step 3-5) do not search echo continuous 2 times, then judge that echo position is incorrect, is transferred to step 2).
CN201810778659.8A 2018-07-16 2018-07-16 A kind of search and track method of the radar return based on interference imaging altimeter Active CN108983188B (en)

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