Multi-Dimensional Signal Processing Algorithms for Sparse Radar Arrays
Project Award Date: 03-01-1999
The goals of the TechSat 21 program involve developing the technologies required to successfully implement a concept where multiple, coherently- linked radar satellites are combined in a sparse cluster. This arrangement creates an overall sensor that provides precise angle-of-arrival (AOA) information by matching four measurements (azimuth, elevation, range, and Doppler mapping) with four key target descriptors (three dimensions of location and radial velocity).
The problem is how to process this wealth of sensor information so the desired target parameters can be extracted effectively and efficiently. Since the sensor provides unique target responses as a general function of three spatial dimensions and velocity, the raw data can be processed with different methods to extract only the information required by a specific application. This processing can be accomplished by organizing the received information in terms of range-Doppler. Each resolution cell in the range-Doppler map may, in fact, reflect a response from multiple targets. However, these targets will not be collocated, and thus, they will be unambiguous in AOA. Therefore, specific range-Doppler information from each individual aperture can be used to resolve targets that are otherwise ambiguous in range-Doppler alone. As the size of the aperture array increases, both in element number and spatial extent, the ability to resolve ambiguous targets will likewise increase and thus allow for an increase in Synthetic Aperture Radar (SAR) image area or Moving Target Indication (MTI) performance. For relatively long aperture times, targets will migrate in range-Doppler, and consequently, the processing required will be more complex. Generally, the targets must be organized and resolved in a spatial-temporal Signal Space and use concepts such as beam-forming and adaptive estimation.
The proposed research will develop these processing algorithms for application to the TechSat21 concept. The research will investigate their performance as a function of target parameters, radar parameters, system errors, and processing complexity. This research will also address how to design orthogonal signals to be optimally transmitted from each aperture in the array, another goal of the TechSat 21 program.
Primary Sponsor(s): Air Force Office of Scientific Research (AFOSR)