DOPPLER DISCRIMINATION IN RELATION TO ECHO DURATION AND DISPLAY FREQUENCY (U)

摘要

An experiment was conducted to determine the effects of speed translating recorded sonar signals on accuracy of doppler recognition. Both double-speeding and half-speeding were investigated. In addition, performance differences attributable to differences in basic display frequency were investigated. It was found that doppler recognition was slightly but systematically better when displayed at a central frequency of 500 cps rather than the 800 cps typically used in shipboard systems. Double-speeding the playback of a recorded signal benefited doppler recognition for echo durations from 40 to 100 ms provided the speeded signal was heterodyned back to a desirable display frequency. Half-speeding was found to produce adverse effects on doppler recognition at all echo durations investigated (40 to 220 ms). (Author)