CN106019278B - A kind of FMCW SAR phase synchronization methods based on distributed satellites - Google Patents
A kind of FMCW SAR phase synchronization methods based on distributed satellites Download PDFInfo
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- CN106019278B CN106019278B CN201610300361.7A CN201610300361A CN106019278B CN 106019278 B CN106019278 B CN 106019278B CN 201610300361 A CN201610300361 A CN 201610300361A CN 106019278 B CN106019278 B CN 106019278B
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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
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
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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
- 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
- G01S13/904—SAR modes
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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
- 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
- G01S13/904—SAR modes
- G01S13/9058—Bistatic or multistatic SAR
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- Engineering & Computer Science (AREA)
- Remote Sensing (AREA)
- Radar, Positioning & Navigation (AREA)
- Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Position Fixing By Use Of Radio Waves (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The present invention provides a kind of distributed satellites FMCW SAR phase synchronization methods based on signal exchange, includes the following steps：T at any time launches transmitting satellite output signal after K frequencys multiplication and N frequencys multiplication respectively；It is mixed after M frequencys multiplication with CF signal again, extracts to obtain transmitting terminal carrier phase difference through spectrum peak.Satellite output signal will be received to be mixed with echo-signal after K frequencys multiplication all the way, obtain dual station echo-signal；Launch after M frequencys multiplication all the way；It is mixed after N frequencys multiplication with the transmitting signal of reception, extracts to obtain receiving terminal carrier phase difference through spectrum peak.The transmitting terminal carrier phase difference of any time t and receiving terminal carrier phase difference are obtained using the above process, the compensation phase of dual station echo-signal is obtained after transmitting terminal carrier phase difference and receiving terminal carrier phase difference are carried out difference.The present invention can improve the measurement frequency of carrier phase difference, improve Phase synchronization precision.
Description
Technical field
The invention belongs to SAR (Synthetic Aperture Radar, synthetic aperture radar) technical field, more particularly to
A kind of FMCW (Linear Frequency Modulated Continuous Wave, linear frequency modulation based on distributed satellites
Continuous wave) phase synchronization method.
Background technology
Distributed satellites FMCW SAR systems are that a kind of distributed satellites radar formation is combined with FMCW SAR technologies
New System Space-based Radar System has the characteristics that miniaturization, data product are at low cost, capability of fast response is strong.The system
Emit FMCW signal, and receives echo-signal simultaneously, since satellite platform is distant, with unmanned plane FMCW SAR systems not
Together, distributed satellites FMCW SAR systems can not provide enough receive-transmit isolations, therefore the system is distributed using transmitting-receiving
Configuration the FMCW signal of transmitting is decayed into proper level, usually receive and dispatch spacing in tens kilometers.However, bistatic
When due to there is transmitting and reception carrier difference, will inevitably caused dual station phase of echo error, bring so-called phase
Bit synchronization problem.
First in-orbit Distributed Spaceborne SAR System is the TanDEM-X systems of Germany, and system that employs based on arteries and veins
The phase synchronization method for rushing signal exchange successfully solves distributed radar Phase synchronization problem.However, system transmitting letter
Number pulse mode is operated in, needs periodically to interrupt normal ground echo admission process, introduce new aliasing and interpolation phase
Position error, this method cannot be directly applied in distributed satellites FMCW SAR systems.Therefore, it is necessary to study for distribution
The phase synchronization method of satellite FMCW SAR systems.
Invention content
The object of the present invention is to propose a kind of distributed satellites FMCW SAR phase synchronization methods based on signal exchange,
Solve the problems, such as the Phase synchronization in distributed satellites FMCW SAR systems.
The technical scheme is that：A kind of distributed satellites FMCW SAR phase synchronization methods based on signal exchange,
Include the following steps：
It is located at any time t：
The output signal of the high steady frequency source of transmitting satellite is divided into three tunnels and is handled：The first via is launched after K frequencys multiplication
It goes, is denoted as first via transmitting signal；Second tunnel is launched after N frequencys multiplication, is denoted as the second tunnel transmitting signal (i.e. synchronizing signal)；
Third road is mixed after M frequencys multiplication with receiving the CF signal of satellite launch, and analog-to-digital conversion and fast is carried out to obtained signal
Fast Fourier transformation is extracted to obtain transmitting terminal carrier phase difference through spectrum peak；
The output signal of the high steady frequency source of reception satellite is divided into three tunnels and is handled：The first via after K frequencys multiplication with reception
The first via transmitting signal echo-signal be mixed, obtain dual station echo-signal；Second tunnel obtains carrier frequency letter after M frequencys multiplication
Number, it is gone out by reception satellite launch；Third road is mixed after N frequencys multiplication with the second tunnel of reception transmitting signal, to what is obtained
Signal carries out analog-to-digital conversion and Fast Fourier Transform (FFT), extracts to obtain receiving terminal carrier phase difference through spectrum peak.
The transmitting terminal carrier phase difference of any time t and receiving terminal carrier phase difference are obtained using the above process, it will
Transmitting terminal carrier phase difference obtains the compensation phase of dual station echo-signal after carrying out difference with receiving terminal carrier phase difference.
The beneficial effects of the invention are as follows：Phase synchronization method provided by the invention, using emit satellite and receive satellite it
Between different three kinds of links be carried out at the same time signal transmitting and receiving, the measurement frequency of carrier phase difference can be improved, improve Phase synchronization
Precision.The extraction of carrier phase difference and ground carrier phase difference on star can be compensated two steps and separated by the present invention simultaneously,
Only need to the carrier phase difference on star be subjected to terrestrial transmission, you can realize the compensation of ground carrier phase difference.Utilize the present invention
The Phase synchronization realized between multi-satellite can be synchronized.
Description of the drawings
Fig. 1 is a kind of processing step of the FMCW SAR phase synchronization methods based on distributed satellites of the present invention；
Fig. 2 is extract real-time carrier phase process schematic on star；
Fig. 3 is phasic synchrony error Performance Prediction result.
Specific embodiment
The present invention is further detailed below in conjunction with the accompanying drawings.
Fig. 1 is a kind of processing step of the FMCW SAR phase synchronization methods based on distributed satellites of the present invention, by star
Carrier phase difference is extracted and ground carrier phase difference compensates two step compositions, and the first step passes through synchronizing signal microwave on star
Link extract real-time carrier phase difference, second step compensate the carrier phase difference included in echo-signal.
Fig. 2 is extract real-time carrier phase process schematic on star, is given real by synchronizing signal microwave link on star
When extract carrier phase difference process, this is the phase locked first step.
Any time t is located at, the phase of the output signal of the high steady frequency source of transmitting satellite isBe divided into three roads into
Row processing：The first via is launched after K frequencys multiplication, is denoted as first via transmitting signal, and phase isSecond tunnel is through N
Launch after frequency multiplication, be denoted as the second tunnel transmitting signal (i.e. synchronizing signal), phase isThird road
(its phase is after M frequencys multiplication) (its phase is with the CF signal that receives satellite launch)
It is mixed, the phase for obtaining normalizing on first via transmitting signal carrier frequency isWhereinIt is the phase for the output signal for receiving the high steady frequency source of satellite, τ represents to receive the transmission of the CF signal of satellite launch
Delay time carries out analog-to-digital conversion and Fast Fourier Transform (FFT) to obtained signal, extracts to obtain transmitting terminal load through spectrum peak
Wave phase difference isWherein tk=k/fsyn, k=0,1 ..., N-1, N expressions are together
Walk number, fsynRepresent Phase synchronization frequency.Wherein, K, N, M are positive integer and value is different, and the value of usual N, M are small
In K, determines according to actual conditions.
The phase for receiving the output signal of the high steady frequency source of satellite isIt is divided into three tunnels to be handled：The first via is through K
(its phase is after frequency multiplication) (its phase is with the echo-signal of first via transmitting signal that receives) mixed
Frequently, dual station echo-signal is obtained, needs the carrier phase compensated the difference to beSecond tunnel obtains after M frequencys multiplication
It to CF signal, is gone out by reception satellite launch, phase is(its phase is after N frequencys multiplication on third road) (its phase is with the second tunnel transmitting signal for receiving) be mixed, it obtains normalizing to
The phase on transmitting signal carrier frequency is all the wayAnalog-to-digital conversion and quick Fu are carried out to obtained signal
In leaf transformation, extract to obtain receiving terminal carrier phase difference through spectrum peak be
Fig. 3 is phasic synchrony error Performance Prediction result.Phase locked second step does not need to carry out in real time, typically exists
The carrier phase difference included in ground imaging precompensation echo-signal.By transmitting terminal carrier phase difference and receiving terminal carrier wave phase
The compensation phase of dual station echo-signal is obtained after the different carry out difference of potential difference, calculation formula is
Wherein, first itemAs need the carrier phase difference compensated, φerr(t) represent by
The residual synchronization phase error that noise, sample interpolation and sampling aliasing are collectively incorporated into, the error determine Phase synchronization scheme
Precision.Horizontal axis represents Phase synchronization frequency in Fig. 3, that is, represents to calculate time of carrier phase difference in the unit interval using the present invention
Number；The longitudinal axis is represented by residual phase synchronous error φ after Phase synchronizationerr(t) the image area phase error standard deviation introduced is different
Curve represents that total phase error (total) (solid line), noise introduce phase error (SNR) (short dash line), sample interpolation is drawn respectively
Applying aspect error (interp) (chain-dotted line) and sampling aliasing introduce phase error (alias) (long dotted line).Institute during Performance Prediction
It is 25 decibels to take synchronizing signal signal-to-noise ratio, and the synthetic aperture time used in imaging is 1 second, by Performance Prediction as a result, working as Phase synchronization
Frequency fsynDuring more than 30Hz, the image area phase error standard deviation of sample interpolation and sampling aliasing error introducing is less than 0.1 degree,
At this point, image area phase error is mainly determined by microwave link signal-to-noise ratio, phase error standard deviation is 0.5213 degree, less than 1 degree,
Phase synchronization precision disclosure satisfy that distributed satellites FMCW SAR system imaging requirements.
The embodiments of the present invention described above are not intended to limit the scope of the present invention, any in the present invention
Modifications, equivalent substitutions and improvements made within spirit and principle etc. should be included in the claims of the present invention
Within.
Claims (1)
1. a kind of distributed satellites FMCW SAR phase synchronization methods based on signal exchange, wherein FMCW refers to that linear frequency modulation connects
Continuous wave, SAR refer to synthetic aperture radar, include the following steps：
It is located at any time t：
The output signal of the high steady frequency source of transmitting satellite is divided into three tunnels and is handled：The first via is launched after K frequencys multiplication, note
Emit signal for the first via；Second tunnel is launched after N frequencys multiplication, is denoted as the second tunnel transmitting signal；Third road after M frequencys multiplication with
The CF signal for receiving satellite launch is mixed, and analog-to-digital conversion and Fast Fourier Transform (FFT) is carried out to obtained signal, through frequency
Spectrum peak extracts to obtain transmitting terminal carrier phase differenceWherein tk=k/
fsyn, k=0,1 ..., N-1, N expression synchronization times, fsynRepresent Phase synchronization frequency；K, N, M be positive integer and value respectively not
Identical, the value of N, M are less than K；Represent moment tkEmit the phase of the output signal of the high steady frequency source of satellite；Represent moment tk+ τ receives the phase of the output signal of the high steady frequency source of satellite, and τ represents to receive the load of satellite launch
The propagation delay time of frequency signal；
The output signal of the high steady frequency source of reception satellite is divided into three tunnels and is handled：The first via after K frequencys multiplication with reception
The echo-signal of transmitting signal is mixed all the way, obtains dual station echo-signal；Second tunnel obtains CF signal after M frequencys multiplication,
It is gone out by reception satellite launch；Third road is mixed after N frequencys multiplication with the second tunnel of reception transmitting signal, to obtained signal
Carry out analog-to-digital conversion and Fast Fourier Transform (FFT), extract to obtain receiving terminal carrier phase difference through spectrum peak be Represent moment tkReceive the output signal of the high steady frequency source of satellite
Phase；Represent moment tkThe phase of the output signal of the high steady frequency source of+τ transmitting satellites；
The transmitting terminal carrier phase difference of any time t and receiving terminal carrier phase difference are obtained using the above process, will be emitted
End carrier phase difference obtains the compensation phase of dual station echo-signal after carrying out difference with receiving terminal carrier phase difference.
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| CN107422323B (en) * | 2017-04-27 | 2019-12-10 | 中国科学院电子学研究所 | bistatic SAR non-interrupt phase synchronization method and device and equipment thereof |
| CN109725295A (en) * | 2018-12-11 | 2019-05-07 | 上海无线电设备研究所 | A kind of spaceborne double-base SAR system phase synchronization method and system based on bi-directional synchronization |
| CN111257876A (en) * | 2020-02-12 | 2020-06-09 | 中国科学院电子学研究所 | Double-base SAR phase synchronization signal processing method and device based on carrier frequency signal |
| CN111693973B (en) * | 2020-05-25 | 2022-10-14 | 北京理工大学 | Distributed system frequency synchronization method based on frequency ratio bidirectional transmission |
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