Polyphase signals with discrete frequency shift keying and zero autocorrelation zone for remote sensing radar

• Published in: Journal of applied remote sensing 2020-10, Vol.14 (4), p.040501-040501
• Main Authors: Ipanov, Roman, Komarov, Aleksey
• Format: Article
• Language: English
• ISSN: 1931-3195; 1931-3195
• DOI: 10.1117/1.JRS.14.040501

Modern synthetic aperture radars (SAR), e.g., space SARs for remote sensing of the Earth, use signals with linear frequency modulation and signals with phase-code shift keying (PCSK) coded by M-sequence (MS) as probing signals. Utilization of PCSK-signals permits an essential improvement of the radar image quality at the stage of its compression on azimuthal coordinate. Polyphase (p-phase where p is a prime number) probing signal with zero autocorrelation zone has been synthesized, which signal represents a sequence of p PCSK-pulses coded by complementary sequences with additional frequency shift-keying of the subpulses of pulses. A comparative analysis of the correlation characteristics of the synthesized three-phase signal with a PCSK-signal coded by ternary MS has been performed. Total correlation characteristics of the signal ensemble used in the mode of the radar aperture synthesis have been also analyzed. The analysis has revealed that in case of a mismatch by Doppler frequency, the level of side lobes of autocorrelation function (ACF) of the synthesized signal is comparable with the level of side lobes of ACF of the PCSK-signal coded by MS. The total ACF of the ensemble consisting on p2 signals has zero side lobes along the entire time axis τ. This makes it possible to use the signal in remote sensing radars to improve the quality of radar images.