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Title: Ambiguity resolution in SAR interferometry by use of three phase centers

Abstract

In a typical interferometric synthetic aperture radar (IFSAR) system employed for terrain elevation mapping, terrain height is estimated from phase difference data obtained from two phase centers separated spatially in the cross-track direction. In this paper we show how the judicious design of a three phase center IFSAR renders phase unwrapping, i.e., the process of estimating true continuous phases from principal values of phase (wrapped modulo 2{pi}), a much simpler process than that inherent in traditional algorithms. With three phase centers, one IFSAR baseline can be chosen to be relatively small (two of the phase centers close together) so that all of the scene`s terrain relief causes less than one cycle of phase difference. This allows computation of a coarse height map without use of any form of phase unwrapping. The cycle number ambiguities in the phase data derived from the other baseline, chosen to be relatively large (two of the phase centers far apart), can then be resolved by reference to the heights computed from the small baseline data. This basic concept of combining phase data from one small and one large baseline to accomplish phase unwrapping has been previously employed in other interferometric problems, e.g., laser interferometry andmore » direction-of-arrival determination from multiple element arrays, The new algorithm is shown to possess a certain form of immunity to corrupted interferometric phase data that is not inherent in traditional two-dimensional path-following phase unwrappers. This is because path-following algorithms must estimate, either implicity or explicity, those portions of the IFSAR fringe data where discontinuities in phase occur. Such discontinuties typically arise from noisy phase measurements derived from low radar return areas of the SAR imagery, e.g., shadows, or from areas of steep terrain slope.« less

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
220445
Report Number(s):
SAND-95-2118C; CONF-9604105-1
ON: DE96008228
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: 10. SPIE`s international symposium on aerospace/defense sensing and controls, Orlando, FL (United States), 8-12 Apr 1996; Other Information: PBD: [1996]
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; SYNTHETIC-APERTURE RADAR; ALGORITHMS; INTERFEROMETRY; MAPPING; CONFIGURATION; DESIGN; PHASE SHIFT; COMPUTERIZED SIMULATION

Citation Formats

Jakowatz, Jr, C V, Wahl, D E, and Thompson, P A. Ambiguity resolution in SAR interferometry by use of three phase centers. United States: N. p., 1996. Web.
Jakowatz, Jr, C V, Wahl, D E, & Thompson, P A. Ambiguity resolution in SAR interferometry by use of three phase centers. United States.
Jakowatz, Jr, C V, Wahl, D E, and Thompson, P A. Fri . "Ambiguity resolution in SAR interferometry by use of three phase centers". United States. https://www.osti.gov/servlets/purl/220445.
@article{osti_220445,
title = {Ambiguity resolution in SAR interferometry by use of three phase centers},
author = {Jakowatz, Jr, C V and Wahl, D E and Thompson, P A},
abstractNote = {In a typical interferometric synthetic aperture radar (IFSAR) system employed for terrain elevation mapping, terrain height is estimated from phase difference data obtained from two phase centers separated spatially in the cross-track direction. In this paper we show how the judicious design of a three phase center IFSAR renders phase unwrapping, i.e., the process of estimating true continuous phases from principal values of phase (wrapped modulo 2{pi}), a much simpler process than that inherent in traditional algorithms. With three phase centers, one IFSAR baseline can be chosen to be relatively small (two of the phase centers close together) so that all of the scene`s terrain relief causes less than one cycle of phase difference. This allows computation of a coarse height map without use of any form of phase unwrapping. The cycle number ambiguities in the phase data derived from the other baseline, chosen to be relatively large (two of the phase centers far apart), can then be resolved by reference to the heights computed from the small baseline data. This basic concept of combining phase data from one small and one large baseline to accomplish phase unwrapping has been previously employed in other interferometric problems, e.g., laser interferometry and direction-of-arrival determination from multiple element arrays, The new algorithm is shown to possess a certain form of immunity to corrupted interferometric phase data that is not inherent in traditional two-dimensional path-following phase unwrappers. This is because path-following algorithms must estimate, either implicity or explicity, those portions of the IFSAR fringe data where discontinuities in phase occur. Such discontinuties typically arise from noisy phase measurements derived from low radar return areas of the SAR imagery, e.g., shadows, or from areas of steep terrain slope.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1996},
month = {3}
}

Conference:
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