Echo Sounder is a kind of acoustic measuring depth equipment, which can measure depth with the time between transmitted wave and echo on condition in which the speed of ultrasonic is fixed.
回声测深仪是用来测量水深的一种声学测量设备，其以水中超声波的传播速度为确定条件，利用发射波与反射回波时间差来测量水深。
When we experiment on mine detection on the sea it is always found that the position of target in echo images is not fixed because of sway of ship and this reduces the veracity of detection.
在海上进行探测水雷的试验中，常常因为船体的摇摆而使回波图像中目标的位置不固定，影响了水雷探测的准确性。
When the radar seeker transmits several different frequency pulses, the echo amplitude of the target follows the Rayleigh distribution and that of the decoy is assumed fixed.
当导引头雷达发射多个不同频率的脉冲信号时，在一定的检测处理时长内目标回波信号幅度服从瑞利分布，而诱饵干扰信号则是幅度固定的。
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