counting frequency meter 计数频率计

frequency counting 频率计数

counting type frequency meter 计数式频率计

counting pulse frequency 计数脉冲频率

high frequency counting 高频计数

frequency counting modulator 频率计数调制器

measuring frequency by counting 计数测频法

pulse-recurrence counting type frequency meter 脉冲重复计数型频率计

measuring the frequency by counting 计数法测频