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THE BISTATIC SAR EXPERIMENT WITH ALOS / PALSAR AND Pi-SAR-L

THE BISTATIC SAR EXPERIMENT WITH ALOS / PALSAR AND Pi-SAR-L. July 29, 2011 IGARSS 2011, Vancouver, Canada Takashi Fujimura , Hideharu Totsuka, Norihiro Imai, Shingo Matsuo, Tsunekazu Kimura (NEC Corporation) Tomoko Ishi, Yoshitaka Oura (NEC Aerospace Systems, Ltd)

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THE BISTATIC SAR EXPERIMENT WITH ALOS / PALSAR AND Pi-SAR-L

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  1. THE BISTATIC SAR EXPERIMENTWITH ALOS / PALSAR AND Pi-SAR-L July 29, 2011 IGARSS 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)

  2. Contents 1. Introduction 2. Bistatic SAR Experiment 3. Analysis of Image 4. Conclusion

  3. 1. Introduction Background Some Spaceborne/airborne bistatic SAR experiments were tried. • 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. Few reports about bistatic SAR with other than TerraSAR-X. The first bistatic SAR experiment using spaceborne PALSAR and airborne Pi-SAR-L on February 27th, 2010. First report : “The First Bistatic SAR Experiment with the Spaceborne SAR : PALSAR and the Airborne SAR : Pi-SAR-L”, 2010-12-SANE, IEICE

  4. 1. Introduction Summary of Experiment 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 conditions • The appropriate setting of control parameters of Pi-SAR-L • The appropriate image processing method • Analysis : 3 features of This Bistatic SAR image • Higher S/N • Lower Az resolution • Difference of detected targets

  5. 2. Bistatic SAR Experiment (1) PALSAR and Pi-SAR-L Spaceborne SAR : Transmitter ALOS (Daichi) / PALSAR 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 Pi-SAR Airborne SAR : Receiver Freq. L-band X-band 1997 - Operation Res. 3 - 20m 1.5 or 3m 20 – 40km 5 - 40km Swath Quad Pol. Quad JAXA NICT Organization PALSAR and Pi-SAR-L have no special hardware for the bistatic SAR.

  6. 2. Bistatic SAR Experiment (2) The Experiment Conditions South (Descending) North PALSAR (transmitter) : FBS mode Pi-SAR-L (receiver) : reception only experiment mode

  7. 2. Bistatic SAR Experiment (3) The Experiment Area (Okazaki city in Japan) North Oto-gawa River Tomei Expressway Tokyo PALSAR’s observationarea Nagoya Kyoto Osaka • Near the center of Japan • Important place for transportation in Japan (c) “Digital Japan” URL http://cyberjapan.jp/ Yahagi-gawa River Japan National Route 1(Tokaido Road) Tokaido Main Line (Railway)

  8. 2. Bistatic SAR Experiment (4) Configuration and Result Receiving duty ~50% PRF 996.9 Hz Transmitter Chirp Generator Antenna PALSAR Recorder Receiver Signal Processor (A/D) PRF 2145.9 Hz Antenna Pi-SAR-L Earth Surface Video Signal Level Telemetry A/D sampling data (in 1 PRI) Code ( 1 Code is 2.47mV) Time (UTC) The both of the video signal and A/D sampling data had been set adequately.

  9. 2. Bistatic SAR Experiment (5) Bistatic Image PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image Az Az This bistatic SAR image has three features. 1. Higher S/N, 2. Lower Az resolution, 3. Difference of detected targets

  10. 3. Analysis of Image (1) Higher S/N PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image Note : the images after gamma correction

  11. 3. Analysis of Image (1) Higher S/N PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image ?? Note : the images after gamma correction Sandbar Watercourse Road Yahagi-gawa River 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.

  12. 3. Analysis of Image (2) Lower Azimuth Resolution PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image 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.

  13. 3. Analysis of Image (2) Lower Azimuth Resolution Az Profile • Az Resolution is low in bistatic image. • The monostatic SAR image : 4.6 m • The bistaic SAR image : 8.4 m Monostatic 4.6m Bistatic 8.4m • The possible reasons belong to the unchanged hardware mainly. • 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. • The instability of two oscillators of PALSAR and Pi-SAR-L • Oscillators of two SARs have no linkage for synchronization. • 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.

  14. 3. Analysis of Image (3) Difference of Detected Targets PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image There are large differences of image at the yellow circles. Reason : The incidence angles were different and/or S/N was high.

  15. 3. Analysis of Image (3) Difference of Detected Targets(Roof of Houses) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image

  16. 3. Analysis of Image (3) Difference of Detected Targets(Roof of Houses) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image

  17. 3. Analysis of Image (3) Difference of Detected Targets(Roof of Houses) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image Note : the images after gamma correction (c) “Digital Japan” URL http://cyberjapan.jp/ Structures is dark at the left image but is bright at the right image.

  18. 3. Analysis of Image (3) Difference of Detected Targets(Roof of Houses) PALSAR/Pi-SAR-L bistatic SAR image This residential were bright. (c) Google The roofs of the houses will be strongly reflected, because of the incidence angle.

  19. 3. Analysis of Image (3) Difference of Detected Targets (Bridges) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image

  20. 3. Analysis of Image (3) Difference of Detected Targets (Bridges) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image “Digital Japan”, http://cyberjapan.jp/

  21. 3. Analysis of Image (3) Difference of Detected Targets (Bridges) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image Note : the images after gamma correction “Digital Japan”,http://cyberjapan.jp/ 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.

  22. 3. Analysis of Image (3) Difference of Detected Targets (Bridges) PALSAR monostatic SAR image PALSAR/Pi-SAR-L bistatic SAR image Note : the images after gamma correction • 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. http://www.kasen.net/@5/yahagi/otogawa/index.htm

  23. 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. • S/N is better,because of the short distance. • The azimuth resolution is lower, because of the unchanged hardware without synchronization. • 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.

  24. Thank you for your attention.

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