Some RADAR and radar-like systems, especially LIDAR, do not offer or maintain coherence in transmission, propagation, detection or processing. Yet they could benefit from properties known in coherent RADAR, such as pulse-compression and un-ambiguous range extending beyond the pulse repetition interval (PRI). The paper suggests on-off {1, 0} modulated waveforms that lend themselves to simple envelope (intensity) detection. Combinations of a-periodic, on-off coded sequences are described that provide excellent pulse-compression when cross-correlated with real-valued mismatched reference sequences.
Pseudo continuous-wave (CW) signals can be implemented using periodic on-off {1,0} sequences that yield Perfect Periodic Cross Correlation (zero sidelobes) with a two-valued {1,-1} or {1,-b} reference sequence. Legendre sequences are of special interest and discussed accordingly, because they provide a large selection of periodic sequences (at all prime lengths). Experimental results with LIDAR range finder and magnetron marine radar are described.
