The influence of small-bit quantization and limitations of the radar signal, retransmitted through DRFM, on the quality of the artificial radar image, formed in SAR

The article considers the influence of quantization and limitations of the retransmitted radar signal in analog-to-digital (ADC) and digital-to-analog (DAC) converters of digital radio frequency memory (DRFM) on the quality of the artificial radar image (RI), formed in a radar with a synthetic aperture antenna (SAR). The DRFM, built on the basis of the inverted Omega-k algorithm, forming an artificial map of the Earth's surface (Man-Made Map) for testing SAR, is investigated. The studies were carried out by numerical methods of parallel modeling of digital signal processing (DSP) processes in MATLAB. Numerical modeling of this DRFM was carried out in single-reflector and multireflector modes of synthesis of digital radio holograms (DRH) with different bit depths of the ADC and DAC, as well as with limitations of the amplitude of the reproduced radio signal. The output RIs (at the SAR output) corresponding to the initial (loaded into DRFM) pictures were obtained, and the levels of generated parasitic components in the obtained images were determined depending on the bit depth of the ADC and DAC and on the level of amplitude limitation of the reproduced radio signal. The distributions of instantaneous values of the reproduced radio signal at the DRFM output were analyzed when simulating several point reflectors (PR). Energy equations were derived for cases of simulating reflections from the underlying surface and from a scene containing many PRs for SAR using DRFM.