Improving Ambiguity Function of Costas signal

This paper presents the effects of modifying Costas signal in time and frequency to improve ambiguity function (AF). The effect of adding frequency spacing, linear frequency modulation, constant space time, and variable space time between sub-pulses of Costas signal are presented and compared. It is shown that a considerable reduction of side-lobe and better Doppler resolution is achieved by using variable spacing between sub-pulses of Costas signal.