SBIR-STTR Award

Existing radars are very powerful and perform many functions. However, they have difficulty resolving multiple targets in the same range cell with similar doppler shifts when the targets are close in angle. Typically, targets closer than one beamwidth of the radar\'s aperture cannot be resolved with conventional radar processing. Signal processing techniques that increase the angular resolution of radars beyond the Rayleigh resolution limit are said to provide "superresolution". Superresolution techniques require intense, numerical operations upon a covariance matrix. Unfortunately, conventional radars do not directly provide the covariance matrix. In this Phase I effort we propose to investigate techniques to increase conventional radar\'s angular resolution through the use of superresolution processing as an "applique". The following innovative techniques are proposed for Phase I and elaborated upon in the proposal: o Indirect covariance matrix measurement o Processing only where targets have been detected o Subarraying to reduce computations and data collection Flam & Russell, Inc. has a great deal of experience implementing superresolution processing to a number of systems; direction finding, radar cross-section measurement as well as non destructive evaluation systems. Thus, we possess the right ingredients to add increased angular resolution of conventional radars in an efficient, cost-effective manner

Keywords:
direction finding adaptive array phased array superresolution covariance matrix

Tracking targets at low elevation angles over the ocean is a difficult task for many radars because both the target and its sea reflected multipath are in the mainbeam of their antenna. Furthermore, they are highly correlated and the clutter level is high because of ocean backscatter. Classic monoplulse tracking techniques fundamentally assume the received return is the direct one from a single target. Thus, they have difficulty when receiving multiple returns from either multiple targets or a single target and one or more multipaths. Superresolution algortihms provide the ability to resolve and track multiple returns even when they are separated by less than the beamwidth of the radar antenna. In the Phase I effort Flam and Russel, Inc. (FR) evaluated the tracking performance of several superresolution algorithms via computer simulation for the missile seeker and shipboard radar scenarios. The results of this effort suggest that tracking performance can be significantly enhanced through their use. In this Phase II effort we propose to demonstrate this performance through a hardware feasibility demonstration. Specifically, we propose to assemble a variety of equipment to conduct an experiment that will demonstrate the performance of these techniques where implemented with real hardware on realistic radar returns.

Keywords:
radar superresolution monopulse shipboard missile seeker tracking low angle clutter