echo frequency variation 回波频率变化性

radio frequency echo signal 射频回声信号

high frequency target echo signal 高频目标回波信号

video frequency echo 视频回波

Echo Radio Frequency Simulator 回波射频信号模拟器

Intermediate Frequency Echo 中频回波

calculation of echo doppler frequency 回波多普勒频率计算

high-frequency echo characteristics 高频回声特性

dual frequency echo sounder data 双频测深仪数据