CN107831504A - Satellite-borne SAR satellite load reduces the processing method of data transfer rate - Google Patents
Satellite-borne SAR satellite load reduces the processing method of data transfer rate Download PDFInfo
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- CN107831504A CN107831504A CN201710877188.1A CN201710877188A CN107831504A CN 107831504 A CN107831504 A CN 107831504A CN 201710877188 A CN201710877188 A CN 201710877188A CN 107831504 A CN107831504 A CN 107831504A
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- 238000003672 processing method Methods 0.000 title claims abstract description 9
- 238000005070 sampling Methods 0.000 claims abstract description 49
- 238000012952 Resampling Methods 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 abstract description 8
- 241000283070 Equus zebra Species 0.000 abstract description 4
- 241001269238 Data Species 0.000 abstract 1
- 238000013144 data compression Methods 0.000 description 3
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000013139 quantization Methods 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
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- 238000012544 monitoring process Methods 0.000 description 1
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Classifications
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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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
- G01S19/05—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing aiding data
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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
- G01S7/4052—Means for monitoring or calibrating by simulation of echoes
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- Radar Systems Or Details Thereof (AREA)
Abstract
The invention provides the processing method that a kind of satellite-borne SAR satellite load reduces data transfer rate, it comprises the following steps：Step 1, input SAR echo datas；Step 2, Doppler center estimation；Step 3, determine down-sampled multiple；Step 4, build down-sampled interpolation kernel function；Step 5, data resampling on star；Step 6, signal resampling.The present invention solves the problems, such as the big data rate that the orientation over-sampling rate height that SAR system design faces under azimuth ambiguity degree and the requirement of zebra G- Design is brought, and then effective guarantee SAR system earth observation performance to a certain extent, has the advantages of protecting signal to noise ratio.
Description
Technical Field
The invention relates to the technical field of signal and information processing, in particular to a processing method for reducing data rate of satellite-borne SAR satellite loads.
Background
Synthetic Aperture Radar (SAR) is widely applied to military and civil fields due to all-weather high-resolution ground observation capability of the SAR all day long, such as battlefield investigation, ocean monitoring, agricultural general survey, topographic mapping and the like, generally, the Radar Pulse Repetition Frequency (PRF) of the SAR system is greater than the doppler bandwidth of the SAR system, which causes that certain redundancy exists in SAR echo data, the data rate of the SAR system echo increases quadratically with the improvement of the Radar high resolution, the data rate of the SAR system is increasingly greater with the continuous improvement of the SAR image resolution demand of people, and the system faces increasingly severe data transmission pressure, at the moment, the research of on-satellite real-time processing to reduce the SAR data rate is an important technical support means for realizing high-resolution imaging of the SAR system in the future.
The on-board real-time data rate reduction processing is a problem that a satellite-borne SAR system designer must consider and cannot avoid. At present, a satellite-borne SAR system mainly reduces the data rate in a satellite data compression mode. Kwok et al propose a Block Adaptive Quantization (BAQ) compression algorithm, which can realize data compression in equal proportion of 8:3 and 8:4, and the algorithm is widely applied to a satellite-borne SAR system, but the algorithm can only reduce the echo data rate by improving the compression ratio, which will cause the increase of SAR image quantization noise and the reduction of SAR image quality.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a processing method for reducing the data rate of a satellite-borne SAR satellite load, which solves the problem of large data rate caused by high azimuth oversampling rate of an SAR system design under the requirements of azimuth ambiguity and zebra pattern design to a certain extent, further effectively ensures the earth observation performance of the SAR system, has the advantage of signal-to-noise ratio preservation, and is realized by carrying out azimuth resampling on echo data received by a satellite.
According to one aspect of the invention, a processing method for reducing data rate of satellite-borne SAR satellite loads is provided, and is characterized by comprising the following steps:
inputting SAR echo data, inputting the SAR echo data into a system, and assuming that the pulse repetition frequency of the system is PRF;
step two, doppler center estimation;
determining down-sampling multiples;
step four, constructing a down-sampling interpolation kernel function as follows:
wherein t is the azimuth pre-sampling time, t a Sampling time for actual orientation, B a,p Processing the bandwidth for the azimuth signal, f dc As a central estimate, f (t; t) a ) Interpolating a kernel function for the downsampling; j represents a complex symbol;
step five, resampling on-satellite data;
step six, resampling the signal, and outputting s (t) according to the format requirement a ) And outputs the down-sampling multiple F.
Preferably, the step five specifically includes the following steps:
fifthly, determining the azimuth sampling time, and assuming the SAR echo data starting time to be t 0 After down-sampling, the sampling time of each direction is as follows:
wherein, t a For the actual azimuth sampling time, t 0 The SAR echo data starting time is represented, PRF is the system pulse repetition frequency, and F is the down-sampling multiple;
fifthly, resampling the signal and determining the azimuth time t a Resampled signal, as follows:
wherein,<·>, t is the azimuth pre-sampling time, t is the operator of rounding and rounding a For the actual azimuth sampling time, PRF is the system pulse repetition frequency, f (t; t) a ) For the downsampling interpolation kernel function, 2N +1 is the number of downsampling kernel function points.
Preferably, the doppler center estimation in step two is performed by using attitude measurement data or raw echo data, assuming that the doppler center estimation value is f dc 。
Preferably, the determination of the down-sampling multiple in the third step is to utilize the azimuth signal processing bandwidth B a,p The following formula:
F＝B a,p /PRF
wherein F is a down-sampling multiple, B a,p For azimuth signal processing bandwidth, PRF is the system pulse repetition frequency.
Compared with the prior art, the invention has the following beneficial effects: the invention solves the problem of large data rate caused by high azimuth oversampling rate of SAR system design under the requirements of azimuth ambiguity and zebra pattern design to a certain extent, further effectively ensures the earth observation performance of the SAR system, has the advantage of signal-to-noise ratio preservation, and is realized by carrying out azimuth resampling on echo data received by a satellite.
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Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic flow chart of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
As shown in fig. 1, the processing method for reducing the data rate of the satellite-borne SAR satellite load of the present invention includes the following steps:
inputting SAR (synthetic aperture radar) echo data, inputting the SAR echo data into a system, and assuming that the pulse repetition frequency of the system is PRF;
estimating the Doppler center, namely estimating the Doppler center by using attitude measurement data or original echo data, and assuming that the Doppler center estimated value is f dc ；
Step three, determining down-sampling multiple, and processing bandwidth B by using azimuth signal a , p Determining a down-sampling multiple as shown in the following formula (1):
F＝B a,p /PRF (1)
wherein F is a down-sampling multiple, B a,p For azimuth signal processing bandwidth, PRF is the system pulse repetition frequency;
step four, constructing a down-sampling interpolation kernel function as the following formula (2):
where t is the azimuth pre-sampling time t a Sampling time for actual orientation, B a,p Processing the bandwidth for the azimuth signal, f dc As a central estimate, f (t; t) a ) Interpolating a kernel function for the downsampling; j represents a complex symbol;
step five, resampling on-satellite data, specifically comprising the following steps:
fifthly, determining the azimuth sampling time, and assuming the initial time of SAR (synthetic aperture radar) echo data as t 0 After down-sampling, the sampling time of each azimuth is as follows (3):
wherein, t a For the actual azimuth sampling time, t 0 The method comprises the steps of taking SAR (synthetic aperture radar) echo data starting time, taking PRF as system pulse repetition frequency, and taking F as down-sampling multiple;
fifthly, resampling the signal and determining the azimuth time t a The resampled signal is expressed by the following equation (4):
wherein,<·>, t is the azimuth pre-sampling time, t a For the actual azimuth sampling time, PRF is the system pulse repetition frequency, f (t; t) a ) Is a down-sampling interpolation kernel function, and 2N +1 is the number of down-sampling kernel function points;
step six, resampling the signal, and outputting s (t) according to the format requirement a ) And outputs the down-sampling multiple F.
The embodiment relates to a processing method for reducing data rate of satellite-borne SAR satellite loads.
The space-borne Synthetic Aperture Radar (SAR) of the embodiment realizes high-resolution imaging to the ground through the azimuth synthetic aperture, and the azimuth signal bandwidth B of the SAR a The following formula (5):
wherein D is a Is the antenna size and v is the platform motion speed;
to satisfy Nyquist's theorem sampling, the radar pulse repetition Period (PRF) needs to be greater than the signal bandwidth B a Usually 1.1-1.2 times oversampling is used to ensure system orientation ambiguityPerformance, but azimuth brings an increase in data rate to oversampling.
The on-board data rate is reduced by adopting on-board real-time processing, the basic principle is that the azimuth resampling is realized by constructing an interpolation kernel function through a time domain and multiplying the interpolation kernel function by an original signal receiving signal, the processing performance of on-board real-time processing down-sampling is verified by adopting Japanese XXX satellite SAR (synthetic aperture radar), the bandwidth of the original echo data signal is 2480Hz, the pulse repetition frequency is 2720Hz, and the original echo data rate is reduced by 9.9% after the down-sampling processing.
Compared with the traditional technology, the invention has the following advantages:
firstly, the processing idea is different from the existing data compression method, and the data rate is reduced from the signal sampling principle for the first time at home and abroad;
secondly, the provided on-satellite real-time resampling method has the advantages of signal-to-noise ratio protection and the like;
and thirdly, the problem of large data rate caused by high azimuth oversampling rate of SAR (synthetic aperture radar) system design under the requirements of azimuth ambiguity and zebra pattern design is solved to a certain extent.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (4)
1. A processing method for reducing data rate of satellite-borne SAR satellite loads is characterized by comprising the following steps:
inputting SAR echo data, inputting the SAR echo data into a system, and assuming that the pulse repetition frequency of the system is PRF;
step two, doppler center estimation;
determining down-sampling multiples;
step four, constructing a down-sampling interpolation kernel function as follows:
where t is the azimuth pre-sampling time t a Sampling time for actual orientation, B a,p Processing the bandwidth for the azimuth signal, f dc As a central estimate, f (t, t) a ) Interpolating a kernel function for the downsampling; j represents a complex symbol;
step five, resampling on-satellite data;
step six, resampling the signal, and outputting s (t) according to the format requirement a ) And outputs the down-sampling multiple F.
2. The method for processing the data rate reduction of the satellite borne SAR satellite load according to claim 1, wherein the step five specifically comprises the following steps:
fifthly, determining the azimuth sampling time, and assuming the SAR echo data starting time to be t 0 After down-sampling, the sampling time of each direction is as follows:
wherein, t a For the actual azimuth sampling time, t 0 The SAR echo data starting time is represented, PRF is the system pulse repetition frequency, and F is the down-sampling multiple;
fifthly, resampling the signal and determining the azimuth time t a Resampled signal, as follows:
wherein,<·>, t is the azimuth pre-sampling time, t a For the actual azimuth sampling time, PRF is the system pulse repetition frequency, f (t, t) a ) For the downsampling interpolation kernel function, 2N +1 is the number of downsampling kernel function points.
3. The method for processing data rate reduction of loading of SAR satellite on board of claim 1, wherein the Doppler center estimation in the second step is performed by using attitude measurement data or raw echo data, assuming that the Doppler center estimation value is f dc 。
4. The method for processing data rate reduction of satellite borne SAR satellite loading according to claim 1, characterized in that the step three for determining the down-sampling multiple is to utilize azimuth signal processing bandwidth B a,p The following formula:
F＝B a,p /PRF
wherein F is a down-sampling multiple, B a,p For azimuth signal processing bandwidth, PRF is the system pulse repetition frequency.
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| CN101483777A (en) * | 2008-12-19 | 2009-07-15 | 西安电子科技大学 | SAR image denoising compressing method based on adaptive multi-dimension Bandelet packet |
| JP2010048603A (en) * | 2008-08-20 | 2010-03-04 | Mitsubishi Electric Corp | Synthetic aperture radar device |
| CN102298137A (en) * | 2010-06-25 | 2011-12-28 | 中国科学院电子学研究所 | Method for compressing adaptive data-rate original data of satellite-borne SAR (Synthetic Aperture Radar) |
| US8159387B1 (en) * | 2010-03-15 | 2012-04-17 | The United States Of America As Represented By The Secretary Of The Navy | Multi-transmitter interferometry |
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Patent Citations (4)
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| JP2010048603A (en) * | 2008-08-20 | 2010-03-04 | Mitsubishi Electric Corp | Synthetic aperture radar device |
| CN101483777A (en) * | 2008-12-19 | 2009-07-15 | 西安电子科技大学 | SAR image denoising compressing method based on adaptive multi-dimension Bandelet packet |
| US8159387B1 (en) * | 2010-03-15 | 2012-04-17 | The United States Of America As Represented By The Secretary Of The Navy | Multi-transmitter interferometry |
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