[电] pulse recurrence counting-type frequency meter

mài chōng zhòng koǔ jì shù xíng pín lǜ jì ㄇㄞˋ ㄔㄨㄥ ㄓㄨㄥˋ ㄎㄡˇ ㄐㄧˋ ㄕㄨˋ ㄒㄧㄥˊ ㄆㄧㄣˊ lv4 ㄐㄧˋ