Page 254 - Fundamentals of Radar Signal Processing
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expected to detect targets at ranges up to P · R . Extend the transmitted
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waveform from M to M + P – 1 pulses. The receiver matched filter remains the
same M-pulse waveform. Still using t = 0 and T = 0, the matched filter output
M
0
will be the waveform shown in Fig. 4.16a. It indicates that the full integrated
2
target power of MA τ = ME will be obtained for a target at the delay T (zero
M
p
in the figure) for which the matched filter is tuned, but also for targets at the
ambiguous delays T + pT, p = 0, …, P – 1. Evaluating the matched filter output
M
for delays T between zero and T allows full-SNR matched filtering of targets
M
at delays up to T + (P – 1)T, corresponding to ranges up to P · R as desired.
M
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The pulse-by-pulse viewpoint is shown in Fig. 4.16b. A target in the Pth delay
interval, (P – 1)T ≤ t < PT, will produce a response in the appropriate range
0
bin in the Pth and later slow time samples. By integrating only samples P
through M + P – 1 in each range bin the design integration gain of M can be
achieved for all targets up to ranges P · R .
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FIGURE 4.16 Effect of extending the transmitted waveform with additional
pulses when P range ambiguities can occur: (a) whole-waveform matched filter
output. (b) slow-time data in pulse-by-pulse processing viewpoint.
Another issue arises with pulse burst waveforms and clutter echoes.