[电] Armstrong frequency-modulation system
a mǔ sī tè lǎng tiáo pín xì tǒng ㄚ˙ ㄇㄨˇ ㄙ ㄊㄜˋ ㄌㄤˇ ㄊㄧㄠˊ ㄆㄧㄣˊ ㄒㄧˋ ㄊㄨㄥˇ