The resistance of bats to jamming

摘要: Abstract : OBSTACLE-AVOIDANCE BY ECHOLOCATING LONG-EARED BATS (Plecotus townsendii) was tested while the bats were flying in random noise. Previous experiments had indicated that could achieve a surprising degree of success when dodging wires room filled with noise band 20 to 50 kc, which covers fundamental frequencies pulses orientation sound used by Plecotus. The present show at given power per cycle, effectiveness masking far greater for 10- 90kc than one merely covered bat pulses, but can still echolocate power, cycle bandwidth, exceeds energy echo. Further broadening spectrum, an upper limit exceeding 120 no discernible effect. effect coherent noise, originating single randomnoise generator connected all loudspeakers, compared noncoherent originated four generators, each supplied one-quarter loudspeakers. In field, always received from least two independent generators. Though seemed fly more assurance obstacle avoidance only slightly and inconsistently better.