Pulsed Signals with Zero Autocorrelation Zone for Synthetic-Aperture Radars

Abstract

A sounding signal with zero autocorrelation zone (ZACZ) that represents a series of two phase-code-shift keyed (PCSK) pulses encoded with complementary sequences of the binary D code is synthesized for synthetic-aperture radars (SARs). Discretes of pulses of the synthesized signal are additionally linearly modulated with respect to frequency for suppression of side lobes (SLs) of the autocorrelation function (ACF) in the presence of the Doppler frequency mismatch. Correlation characteristics of the synthesized signal are compared with the characteristics of the signal without modulation of discretes and PCSK signal encoded with the M sequence (MS). Total correlation characteristics of an ensemble of signals are analyzed in the regime of synthesis of the SAR aperture. In the presence of the Doppler frequency mismatch, the level of all ACF SLs in the ZACZ of the synthesized signal is lower than the level of the MS-encoded PCSK signal. The total ACF of an ensemble of four signals has zero SLs along the entire time axis τ. In the presence of the frequency mismatch, the SL level of the ACF is lower than the SL level of the total ACF of the ensemble of four MS-encoded PCSK signals.