回波频率echo: n. (pl. echoes) 1.回声,反响;共鸣,反 ...frequency: n. 1.屡次,频仍,频繁。 2.(脉搏等的)次数,出现 ...dual frequency echo-sounder: 双频道回声测探仪frequency-modulated echo signal: 调频回波信号radio frequency echo signal: 射频回声信号下载手机词典可随时随地查词查翻译