A PROPOSITION TO VALUATE EXPANDED IMPULSES IN PULSE RADAR SYSTEMS USING OPTIMUM UNBIASED ESTIMATION

In pulse radar systems using expanded impulses, in the receiver the us ual method of signal processing is pulse compression by matched filter s. When using this kind of signal processing, the autocorrelation side lobes of the expanded impulse severely limit the detectability of smal l targets situated near large targets. By using an optimum unbiased es timator instead of a matched filter, the harmful effects of the autoco rrelation sidelobes can be totally eliminated. It is first shown how t he estimation theory known from other technical areas can be advantage ously applied to the processing of expanded impulses in radar receiver s. Secondly, new criteria for the valuation of expanded impulses are p roposed. Such criteria are necessary because the autocorrelation peak- to-sidelobe ratio which is a suitable criterion in the case of matched filtering is no longer adequate if optimum unbiased estimation is use d. The new criteria are applied to several well known expanded impulse s as e.g. Frank coded and P3 coded waveforms. It is shown that wavefor ms which, on account of rather high autocorrelation sidelobes, would b e ill suited in the case of matched filtering may be well suited in th e case of optimum unbiased estimation.