STAP for SAR
Abstract
This paper describes the application of STAP (Space Time Adaptive Processing) to Synthetic Aperture Radar (SAR) systems. SAR is a microwave sensor that allows us to have a high resolution mapping of electromagnetic (e.m.) backscatter from an observed scene. A two-dimensional image is provided in the radar polar coordinates, i.e.: slant range and azimuth. High resolution in slant range is obtained by transmitting a coded waveform, with a large value of the time - bandwidth product, and coherently processing the echoes in a filter matched to the waveform. High resolution along the transversal direction is achieved by forming a synthetic aperture. This requires: (i) to put the radar on board of a moving platform, e.g.: an aircraft or a satellite; (ii) to record the e.m. signals from each scatterer which is illuminated by the moving antenna beam in successive instants of time, and (iii) to coherently combine the signals - via a suitable azimuthal matched filter - thus focusing the sliding antenna pattern in a narrower synthetic beam AUS84j. The advantage of combining SAR and STAP is evident: the detected moving target is shown on top on the SAR image of the sensed scene. The paper is organised as follows. The description of the technical problem to tackle is in section 2; also a look to the state of the art is included. It is well known that the SAR image of a moving target presents a number of aberrations: these are briefly reviewed in section 3. Signal processing schemes are described in Section 4 which is the core of the paper. We move from a suitable modification of the - conventional MTI and Pulse Doppler (PD), to Along Track Interferometry (ATI) SAR, to Displaced Phase Center Antenna (DPCA) - the predecessor of STAP. Finally the last described processing scheme is the one that combines the data in the three domains: space, time and frequency. Some of the schemes are tested with simulated data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2003
- Accession Number
- ADP014042
Entities
People
- A. Farina