Abstract: 1. A Doppler frequency responsive electronic proximity fuse comprising, in combination:A. means for transmitting signals at at least two different frequencies and for receiving Doppler frequency signals which are reflected by a target;B. means forming a first amplifier channel for amplifying only those Doppler frequency signals which are received when said transmitting-receiving means transmit at one of said two different frequencies;C. means forming a second amplifier channel for amplifying only those Doppler frequency signals which are received when said transmitting-receiving means transmit at the other of said two different frequencies;D.