超音波法液位元元元元元元测定
ultra-sonic method of liquid meaduremert
超单元组合—超单元—单元划分
divition of “super unit combine—super unit—unit
本振频率
local oscillating fre quency
local oscillator
本振频率漂移
frequency drifting of the LNB
本振频率选取
Local frequency selection
本振频偏
the frequency leaning of the LNB
基本单元构筑
Building from basic units