测量方波、矩形波一类信号的频率通常使用频率计。但在下述几种情况下,用频率计测量则带来困难和不便: 1.若所测信号的周期较长(如长达数千,数万秒以上),则测量人员需在测量现场等待很长的时间。而且在每作一次测量后应及时读数,(否则频率计自动清零后,对读数无法保存。) 2.若需同时测矩形波的上顶和下底时间(或测方波的对称性)时,需要作两次测量,同时还要附加额 Measurement of square wave, rectangular wave A class of signal frequency is usually used frequency meter. However, in the following cases, the use of frequency measurement is the result of the difficulties and inconveniences: 1. If the measured signal cycle longer (such as up to thousands, more than tens of thousands of seconds), the surveyors need to wait at the measurement site A long time. And after each measurement should be timely reading, (otherwise the frequency meter automatically cleared, the reading can not be saved.) 2. If you want to simultaneously measure the rectangular wave on the top and bottom of the time (or measure the symmetry of the square wave) When the need for two measurements, but also with the additional amount