Noise in crystal detectors (historical)
Long pulses and intra-pulse modulation are also your friend. Instead of 4uSec pulse from magnetron, you can have longer pulses at much lower power, and digitize the inphase-quadrature channels in the receiver after down-conversion. Once digitized, do whatever signal-processing (correlation, dispreading, bandwidth reduction) you seek.

Low Probability (of) Intercept airborne radars, on fighters and bombers, use this approach.