长延时回声消除
long time delay echo cancellation
超声波回波测距
ultrasonic wave echo measuring distance
海面回波波谱
Spectra of ocean return signal
回波时间预估
Time-estimating of arrival
连续波回波信号
contiuous-wave echo signal
脉冲回波波形分析
Laser echo waveform analysis
脉波延时调变
pulse duration modulation