While the stepped-frequency waveform synthesis for wideband imaging leads to a flexible and simplified implementation of the transmit and receive beamformer, the sparse multi-frequency array with proper frequency selection can obtain reasonable image quality with the same advantages and much less data acquisition time. Random, uniform-random, tapered random, and tapered uniform random reduced frequency selection schemes have been presented for indoor imaging. It is shown that for a single target scene, the uniform-random frequency selection can achieve better image quality, compared to the random frequency selection method, around the target location. For a scene in which multiple targets are close together, uniform-random reduced set of frequencies retains the advantage over random reduction. However, in the presence of other strong targets away from main target cluster, little advantage of uniform random over random remains. In such situations, tapered density of retained frequencies is shown to provide improved image quality.

Inspec keywords: radar imaging; array signal processing; radar signal processing

Other keywords: random reduction; transmit beamformer; target cluster; wideband imaging; receive beamformer; indoor imaging; data acquisition time; tapered uniform random reduced frequency selection schemes; image quality; sparse stepped-frequency waveform synthesis design; sparse multifrequency array; through-the-wall radar imaging

Subjects: Optical, image and video signal processing; Radar equipment, systems and applications