ANALYSIS OF LADAR RANGE RESOLUTION ENHANCEMENT BY SINUSOIDAL PHASE MODULATION

The ability of a radar system to resolve two or more separate returns from a combined echo is related to the effective correlation band-widt h of the pulse emitted by the ladar system. Phase modulation of an out going pulse introduces additional frequency components, which increase s the effective correlation bandwidth of the pulse and thus improves t he range resolution of the system. In this paper, we discuss the gener al theoretical basis for achieving improved range resolution using a m odulated waveform and a matched filter receiver. We then demonstrate t hese concepts by considering the particular case of improved range res olution for a sinusoidally phase modulated carrier with a rectangular amplitude function. We also perform computer simulations with a realis tic pulsed ladar envelope possessing the same modulation function. Our calculations indicate that the resolution of a pulsed ladar system ma y be improved by a factor of 70 with a phase-modulated pulse and a mat ched-filter receiver.