Bistatic SAR data acquisition and processing using SABRINA ...
THE BISTATIC SAR EXPERIMENT WITH ALOS / PALSAR AND Pi-SAR-L
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IGARSS2011 : FR3.T01.1: THE BISTATIC SAR EXPERIMENT WITH ALOS / PALSAR AND Pi-SAR-L
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THE BISTATIC SAR EXPERIMENTWITH ALOS / PALSAR AND Pi-SAR-L
July 29, 2011IGARSS 2011, Vancouver, Canada
Takashi Fujimura, Hideharu Totsuka, Norihiro Imai, Shingo Matsuo, Tsunekazu Kimura (NEC Corporation)
Tomoko Ishi, Yoshitaka Oura (NEC Aerospace Systems, Ltd)Masanobu Shimada (Japan Aerospace Exploration Agency)
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Contents
1. Introduction2. Bistatic SAR Experiment3. Analysis of Image4. Conclusion
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1. Introduction
Some Spaceborne/airborne bistatic SAR experiments were tried.
The first bistatic SAR experiment using spaceborne PALSAR and airborne Pi-SAR-L on February 27th, 2010.
Background
Few reports about bistatic SAR with other than TerraSAR-X.
M. Rodriguez-Cassola, etc., “Bistatic TerraSAR-X / F-SAR Spaceborne-Airborne SAR Experiment: Description, Data Processing, and Results” IEEE Trans. on G.E., vol.48, No.2
I. Walterscheid, etc., “Bistatic SAR Experiments With PAMIR and TerraSAR-X - Setup, Processing, and Image Results”, IEEE Trans. On . G.E. vol.48, No.8
and so on.
First report : “The First Bistatic SAR Experiment with the Spaceborne SAR : PALSAR and the Airborne SAR : Pi-SAR-L”, 2010-12-SANE, IEICE
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1. Introduction
Pi-SAR-L has NO special function for bistatic SAR observation. (function for receiving time synchronization)
Bistatic SAR operation and image processing could succeed only with the followings.
The appropriate choice of the experiment conditionsThe appropriate setting of control parameters of Pi-SAR-LThe appropriate image processing method
Summary of Experiment
Analysis : 3 features of This Bistatic SAR image1. Higher S/N2. Lower Az resolution3. Difference of detected targets
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2. Bistatic SAR Experiment (1) PALSAR and Pi-SAR-L
Spaceborne SAR : Transmitter
Freq. : L-band
Operation : Jan, 2006 – April, 2011
Res. : 10 / 20 / 30 / 100 m
Swath : 70 / 70 / 30 / 350 km
Pol. : Single/Dual/Quad/Single
Airborne SAR : ReceiverFreq. X-bandL-band
Operation 1997 -
Res. 1.5 or 3m3 - 20m
Swath 20 – 40km 5 - 40km
Pol. Quad
Organization JAXA NICT
ALOS (Daichi) / PALSAR
Pi-SAR
PALSAR and Pi-SAR-L have no special hardware for the bistatic SAR.
Quad
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2. Bistatic SAR Experiment (2) The Experiment Conditions
700km
8500m
ALOS/PALSAR
Pi-SAR-L
34.3deg
40deg
North
South (Descending) Parameters PALSAR Pi-SAR-L
1 Date, Time Feb. 27th(Sat), 2010 10:23:17(+/-30sec)
(Japan Standard Time)
2 Area Around Okazaki city, Aichi, Japan
3 Observation mode
High Resolution
Experiment mode(Reception only)
4 Polarization HH H
5 Height 700 km 8500 m
6 Swath 70 km -
7 Off-nadir Angle
34.3 degrees
40 degrees
8 PRF 2145.9 Hz 996.9 Hz
9 Velocity 7500 m/s 200 m/s
10 STC OFF OFF
11 AGC/MGC MGC MGC
12 MGC ATT 25dB 25dB
13 Transmitted Pulse Width
27micro sec
No Transmission
14 Transmitted Band Width
28 MHz No Transmission
15 Received Band Width
28 MHz 30 MHz
PALSAR (transmitter) : FBS modePi-SAR-L (receiver) : reception only
experiment mode
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2. Bistatic SAR Experiment (3) The Experiment Area (Okazaki city in Japan)
North
PALSAR’s observationarea
(c) “Digital Japan” URL http://cyberjapan.jp/
Osaka
Tokyo
Nagoya
Kyoto
Yahagi-gawa River
Oto-gawa River Tomei Expressway
Japan National Route 1(Tokaido Road)
Tokaido Main Line(Railway)
•Near the center of Japan•Important place for transportation in Japan
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2. Bistatic SAR Experiment (4) Configuration and Result
ReceiverSignal
Processor(A/D)
Antenna
Recorder
Pi-SAR-L
Chirp Generator
Transmitter
Antenna
Earth Surface
PALSAR
The both of the video signal and A/D sampling data had been set adequately.
Receiving duty ~50%PRF 996.9 Hz
PRF 2145.9 Hz
Video Signal Level Telemetry A/D sampling data (in 1 PRI)
Time (UTC)
Co
de
( 1
Co
de
is 2
.47
mV
)
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2. Bistatic SAR Experiment (5) Bistatic Image
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
This bistatic SAR image has three features. 1. Higher S/N, 2. Lower Az resolution, 3. Difference of detected targets
AzAz
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3. Analysis of Image (1) Higher S/N
Note : the images after gamma correction
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (1) Higher S/N
Note : the images after gamma correction
Road
Watercourse Sandbar
Difference between sandbars and watercourses appears in bistatic image.
but these can not be found in monostatic image.Reason : Received signal level was high because of short distance.
Yahagi-gawa River
??
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (2) Lower Azimuth Resolution
The narrow roads in the monostatic SAR image are clearer than the ones in the bistatic SAR image.
Az Profile (Next page)
Unfortunately the azimuth resolution of the bistatic SAR image seems to be lower than that of the monostatic SAR image.
Reason : Pi-SAR-L was not changed for simple feasibility trial.
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (2) Lower Azimuth Resolution
The possible reasons belong to the unchanged hardware mainly.1.The shortage of sampling data
Pi-SAR-L has no function for the receiving time synchronization.Received data by Pi-SAR-L has about only half of the original
signal.2.The instability of two oscillators of PALSAR and Pi-SAR-L
Oscillators of two SARs have no linkage for synchronization.3.The relative motion between ALOS and the aircraft
SAR processor has the excellent motion compensation function. But the influence of the relative motion may be left.
Az Resolution is low in bistatic image.The monostatic SAR image : 4.6 mThe bistaic SAR image : 8.4 m
Az ProfileThe Rail Bridge of Meitetsu-Nagoya Line across Oto-gawa River
-25
-20
-15
-10
-5
0
-20 -15 -10 -5 0 5 10 15 20
Az [m]
Leve
l [dB
]
PALSAR monostatic SAR PALSAR/Pi-SAR-L bistatic SAR
8.4m
4.6mBistatic
Monostatic
Az Profile
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3. Analysis of Image (3) Difference of Detected Targets
There are large differences of image at the yellow circles.Reason : The incidence angles were different and/or S/N was high.
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Roof of Houses)
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Roof of Houses)
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Roof of Houses)
Structures is dark at the left image but is bright at the right image.
(c) “Digital Japan” URL http://cyberjapan.jp/
Note : the images after gamma correction
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Roof of Houses)
(c) Google
This residential were bright.
The roofs of the houses will be strongly reflected, because of the incidence angle.
PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Bridges)
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Bridges)
“Digital Japan”, http://cyberjapan.jp/
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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Note : the images after gamma correction
3. Analysis of Image (3) Difference of Detected Targets (Bridges)
All bridges on the map appear in the bistatic SAR image. It is difficult to detect two bridges in the monostatic SAR image.
Its reason will be the different incidence angle and high S/N.
“Digital Japan”,http://cyberjapan.jp/
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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3. Analysis of Image (3) Difference of Detected Targets (Bridges)
http://www.kasen.net/@5/yahagi/otogawa/index.htm
The width of this bridge : ~ 2 m << PALSAR resolution (10m/2look)
The monostatic image : not clear.The bistatic image : clear.Reason : difference of incidence
angles and/or high S/N.
Note : the images after gamma correction
PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image
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4. Conclusion The first PALSAR / Pi-SAR-L bistatic SAR experiment was
succeeded. Bistatic SAR observation was possible without special functions. This bistatic SAR image has 3 features.
1. S/N is better,because of the short distance.
2. The azimuth resolution is lower, because of the unchanged hardware without synchronization.
3. Some different targets can be detected, because of the different incidence angles and/or high S/N.
Future Work Unfortunately ALOS has been lost in this April. As future work, the next experiment is expected
with ALOS-2 and Pi-SAR-L2 under development.
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Thank you for your attention.