Progress in the development of the CCRS along-track interferometer

The CCRS C-band SAR owned and operated by the Canada Centre for Remote Sensing (CCRS) was modified in 1991 to operate in an across-track C-band interferometric mode for derivation of terrain elevation. This mode has now been extended such that the two C-band receivers can be used with two separate, almost identical, antennas aligned in the along-track direction thereby creating a SAR capable of detecting and measuring target radial motion. Two new C(H) antennas have been mounted on the right-hand side of the Convair 580 to form the along-track C-band interferometer. The antennas share a common, rigid, mounting structure and the phase centres are separated by 0.5 m. The primary application for this mode will be in ocean monitoring R&D; SAR wave and wake imaging, measurement of coastal and ocean currents, estimation of pack-ice drift, detection of sub-surface sand waves through current modulation, etc. while the short baseline dictated by the existing radome leads to a relatively low sensitivity to radial motion, approximately 24° per m/s, the time between image formation at the same azimuth geometry is small (less than 2 ms) with respect to typical C-band ocean coherence times (around 50-100 ms). This, combined with a good signal-to-noise ratio, will allow relatively low phase noise on the interferometric products and therefore adequate sensitivity to radial motion for most situations. A description of the new system and of ground and airborne testing are given