Creating and sharing knowledge for telecommunications

Project: Signal and Image Processing in Synthetic Aperture Radar

Acronym: PROSAR
Main Objective:
This project addresses the following research topics topics in synthetic aperture radar (SAR): (1) Moving target detection and estimation; (2) Interferometry; (3) Image restoration.

(1) Moving target detection, estimation, and imaging is important for wide area surveillance systems with limited revisit times.
(2) The problem of interferometry is essentially the estimation of absolute phase from a pair (or more) SA images. Topographic maps are then obtained with basis on the estimated absolute phase images.
(3) The pixel amplitude of SA images are, under mild conditions, a sample of a Rayleigh random variable. Therefore, the image amplitudes corresponding to an homogeneous region exhibit random fluctuations, termed ''speckled noise''.

The following goals have been pursued, concerning each of the three referred topics:
(1) Developing solutions to the so-called ''blind angle ambiguity'' problem. It means that using just an antenna it is impossible to infer the direction of the velocity vector. One way to remove the blind angle ambiguity is to make simultaneous bistatic SA measurements with two different antennas. Aiming at the resolution of the blind angle ambiguity problem with only one antenna, it is proposed the exploitation of recent results, derived by the proponents, on the relations between the received signal and the moving target velocity.
(2) Developing Bayesian approaches to the absolute phase estimation in the presence of discontinuities. The inclusion of discontinuities is relevant to obtain meaningful estimates. On the other hand, most methods proposed in the open literature do not take discontinuities into account.

(3) Developing Bayesian approaches to the amplitude restoration that, as in item (2), take the amplitude discontinuity into account.
Reference: POSI/CPS/34071
Funding: FCT/POSI
Start Date: 01-01-2001
End Date: 31-12-2004
Team: José Manuel Bioucas Dias, Paulo Alexandre Carapinha Marques
Groups: Pattern and Image Analysis – Lx
Local Coordinator: José Manuel Bioucas Dias

Associated Publications