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- frequency directing device 频率引导装置
- The first of the British advantage was the development of High Frequency Direction Finders (HD/DF or “huff duff”) for shipboard use. 英国首先的优势是装备在甲板侧弦的高频方向定位仪（HD/DF）。
- Intermediate frequency direct sampling 中频直接采样
- He varied the transmission frequency. 他变换了无线电传送的频率。
- An electronic device that converts one frequency of a radio signal to another. 变频器将无线电讯号从一种频率转换成另一种频率的电子装置
- A unit of frequency equal to one cycle per second. 赫兹频率的单位，等于每秒一周
- The Frequency Tripler is a key device of FFTS. 分频输电系统的关键设备是培频变压器。
- High and very high frequency direction finding 高频和甚高频测向仪
- Medium-high frequency direction finding station 中高频测向台
- very high frequency direction finding 甚高频测向
- very high frequency direction finder 甚高频测向器
- medium frequency direction finder station 中频测向站
- High Frequency Direction Finding Systems 高频方向寻找系统
- Fatal accidents have decreased in frequency over recent years. 近年来死亡事故发生的频率已经下降。
- flow directing device 直流装置
- high frequency direction changing ratio 高频换向
- High and Very High Frequency Direction Finder 高频和甚高频定向仪
- High Frequency Direction Finding 高频测向
- We can often correlate age with frequency of illness. 年龄的大小往往与发病率有关。
- Medium and Very High Frequency Direction Finder 中频与甚高频测向器
