Correlating Synthetic Aperture Radar (CoSAR)

This paper presents the correlating synthetic aperture radar (CoSAR) technique, a novel radar imaging concept to observe statistical properties of fast decorrelating surfaces. A CoSAR system consists of two radars with a relative motion in the along-track (cross-range) dimension. The spatial autocorrelation function of the scattered signal can be estimated by combining quasi-simultaneously received radar echoes. By virtue of the Van Cittert-Zernike theorem, estimates of this autocorrelation function for different relative positions can be processed by generating images of several properties of the scene, including the normalized radar cross section, Doppler velocities, and surface topography. Aside from the geometric performance, a central aspect of this paper is a theoretical derivation of the radiometric performance of CoSAR. The radiometric quality is proportional to the number of independent samples available for the estimation of the spatial correlation, and to the ratio between the CoSAR azimuth resolution and the real-aperture resolution. A CoSAR mission concept is provided where two geosynchronous radar satellites fly at opposing sides of a quasi-circular trajectory. Such a mission could provide bidaily images of the ocean backscatter, mean Doppler, and surface topography at resolutions on the order of 500 m over wide areas.

[1]  G. Krieger,et al.  SweepSAR: Beam-forming on receive using a reflector-phased array feed combination for spaceborne SAR , 2009, 2009 IEEE Radar Conference.

[2]  Bertrand Chapron,et al.  Direct measurements of ocean surface velocity from space: Interpretation and validation , 2005 .

[3]  H. Hersbach,et al.  An improved C-band scatterometer ocean geophysical model function: CMOD5 , 2007 .

[4]  P. H. Cittert,et al.  Die Wahrscheinliche Schwingungsverteilung in Einer von Einer Lichtquelle Direkt Oder Mittels Einer Linse Beleuchteten Ebene , 1934 .

[5]  F. J. Wentz,et al.  A model function for ocean radar cross sections at 14.6 GHz , 1984 .

[6]  W Pfister,et al.  The wave-like nature of inhomogeneities in the E-region , 1971 .

[7]  Donald E. Barrick,et al.  Ocean Surface Currents Mapped by Radar , 1977, Science.

[8]  Irving S. Reed,et al.  On a moment theorem for complex Gaussian processes , 1962, IRE Trans. Inf. Theory.

[9]  Marc Rodriguez-Cassola,et al.  Correlating SAR (CoSAR): Concept, performance analysis, and mission concepts , 2013, 2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS.

[10]  K. Gurgel,et al.  Wellen Radar (WERA): a new ground-wave HF radar for ocean remote sensing , 1999 .

[11]  C. Ruf,et al.  Interferometric synthetic aperture microwave radiometry for the remote sensing of the Earth , 1988 .

[12]  Antoni Broquetas,et al.  Geosynchronous SAR Focusing With Atmospheric Phase Screen Retrieval and Compensation , 2013, IEEE Transactions on Geoscience and Remote Sensing.

[13]  G.P. Cardillo.  On the use of the gradient to determine bistatic SAR resolution , 1990, International Symposium on Antennas and Propagation Society, Merging Technologies for the 90's.

[14]  F. Zernike.  The concept of degree of coherence and its application to optical problems , 1938 .

[15]  Ronald F. Woodman,et al.  A poststatistics steering technique for MST radar applications , 1990 .

[16]  Fabio Rocca,et al.  The wavenumber shift in SAR interferometry , 1994, IEEE Trans. Geosci. Remote. Sens..

[17]  J. P. Ruina,et al.  Some Early Developments in Synthetic Aperture Radar Systems , 1962, IRE Transactions on Military Electronics.

[18]  Gerhard Krieger,et al.  Advanced Concepts for Ultra-Wide-Swath SAR Imaging , 2008 .

[19]  W. Brown.  Synthetic Aperture Radar , 1967, IEEE Transactions on Aerospace and Electronic Systems.

[20]  D. Munson,et al.  A tomographic formulation of spotlight-mode synthetic aperture radar , 1983, Proceedings of the IEEE.

[21]  Jean L. Pacelli,et al.  Synthetic Aperture Radar Imaging from an Inclined Geosynchronous Orbit , 1983, IEEE Transactions on Geoscience and Remote Sensing.

[22]  Juan Carlos Merlano-Duncan,et al.  Carrier phase synchronisation scheme for very long baseline coherent arrays , 2012 .

[23]  Stephanie Thalberg,et al.  Interferometry And Synthesis In Radio Astronomy , 2016 .

[24]  Malcolm Davidson,et al.  GMES Sentinel-1 mission , 2012 .

[25]  T. Johnsen.  Time and frequency synchronization in multistatic radar. Consequences to usage of GPS disciplined references with and without GPS signals , 2002, Proceedings of the 2002 IEEE Radar Conference (IEEE Cat. No.02CH37322).

[26]  Gerhard Krieger,et al.  Impact of oscillator noise in bistatic and multistatic SAR , 2005, Proceedings. 2005 IEEE International Geoscience and Remote Sensing Symposium, 2005. IGARSS '05..

[27]  D. M. Le Vine,et al.  Synthetic aperture radiometer systems , 1999, IMS 1999.

[28]  T. Barnett,et al.  Remote Sensing of Ocean Currents , 1989, Science.

[29]  John G. Proakis,et al.  Digital Signal Processing: Principles, Algorithms, and Applications , 1992 .

[30]  Jong-Sen Lee,et al.  Intensity and phase statistics of multilook polarimetric and interferometric SAR imagery , 1994, IEEE Trans. Geosci. Remote. Sens..

[31]  Michael W. Hoffman,et al.  Pulse pair beamforming and the effects of reflectivity field variations on imaging radars , 2004 .

[32]  Oliver Montenbruck,et al.  Satellite Orbits: Models, Methods and Applications , 2000 .

[33]  Christopher S. Ruf,et al.  Error analysis of image reconstruction by a synthetic aperture interferometric radiometer , 1991 .

[34]  Kamal Sarabandi,et al.  Microwave Radar and Radiometric Remote Sensing , 2013 .

[35]  Gerhard Krieger,et al.  Efficient Time-Domain Image Formation with Precise Topography Accommodation for General Bistatic SAR Configurations , 2011, IEEE Transactions on Aerospace and Electronic Systems.

[36]  Sara Venafra,et al.  XMOD2—An improved geophysical model function to retrieve sea surface wind fields from Cosmo-Sky Med X-band data , 2013 .

[37]  Paco López-Dekker,et al.  Phase Synchronization and Doppler Centroid Estimation in Fixed Receiver Bistatic SAR Systems , 2008, IEEE Transactions on Geoscience and Remote Sensing.