33. A range correlator for target detection, comprising: a transmitter for transmitting a transmit signal modulated by a digital reference word of bit length L; a receiver responsive to reflected transmitted signals which have been reflected from a target, said receiver including a means for providing a digital bit stream of digital signals recovered from said reflected transmitted signals; and a digital correlator responsive to said receiver digital bit stream, comprising: means for providing a set of ramp weights W(k), where k=1 to L/N, where N is a number of word segments comprising said received digital word, each word segment having L/N bits; ramp-weighting summing means for forming a ramp-weighted sum over each of said N word segments, said summing means comprising means for accumulating the respective sums of a product of a reference word bit with a product of a corresponding received bit comprising said segment with a ramp weight W(k) for each bit comprising said word segment; uniformly-weighting summing means for forming a uniformly-weighted sum over each of said N word segments, said summing means comprising means for accumulating the respective sums of a product of a reference word bit with a corresponding received word bit for each bit comprising said word segment; and means for forming a digital correlator output signal at a rate equal to the word segment rate, each output signal comprising a triangular-weighted sum of scaled versions of said ramp-weighted sums and said uniformly-weighted sums over a plurality of preceding word segments covering a predetermined plurality of received words, whereby degradation of said correlator performance caused by Doppler shift modulation on said received signals is reduced.
33. A range correlator for target detection, comprising: a transmitter for transmitting a transmit signal modulated by a digital reference word of bit length L; a receiver responsive to reflected transmitted signals which have been reflected from a target, said receiver including a means for providing a digital bit stream of digital signals recovered from said reflected transmitted signals; and a digital correlator responsive to said receiver digital bit stream, comprising: means for providing a set of ramp weights W(k), where k=1 to L/N, where N is a number of word segments comprising said received digital word, each word segment having L/N bits; ramp-weighting summing means for forming a ramp-weighted sum over each of said N word segments, said summing means comprising means for accumulating the respective sums of a product of a reference word bit with a product of a corresponding received bit comprising said segment with a ramp weight W(k) for each bit comprising said word segment; uniformly-weighting summing means for forming a uniformly-weighted sum over each of said N word segments, said summing means comprising means for accumulating the respective sums of a product of a reference word bit with a corresponding received word bit for each bit comprising said word segment; and means for forming a digital correlator output signal at a rate equal to the word segment rate, each output signal comprising a triangular-weighted sum of scaled versions of said ramp-weighted sums and said uniformly-weighted sums over a plurality of preceding word segments covering a predetermined plurality of received words, whereby degradation of said correlator performance caused by Doppler shift modulation on said received signals is reduced. 35. The correlator of claim 33 further comprising means for digitally filtering said digital correlator output signals with a digital low-pass filter to attenuate sidebands of uncorrelated signals.