多年来,在电气测量技术领域中,指针式仪表、电位差计以及电桥等测量设备一直占据着统治地位。但是,近二十多年来,尤其是近十年来,随着科学技术的飞速发展,在生产斗争和科学实验领域中,不断地对电气测量技术提出了更高的和更新的要求,这些仪表已经不能很满意地完成这一要求,如高精度、高灵敏度、高速度以及自动化等,数字电表就是在这种情况下产生和发展的。数字仪表的种类很多,分类方法也很多,但是大多数情况是根据仪表的用途(亦即被测量的性质)进行分类,如电子计数器,数字相 Over the years, measuring instruments such as pointer meters, potentiometers and bridges have dominated electrical measurement technology. However, with the rapid development of science and technology in the recent two decades or more, especially in the past ten years, higher and newer requirements have been put forward in electrical measurement technologies in the fields of production struggle and scientific experiments. These instruments This requirement has not been satisfied satisfactorily, such as high-precision, high-sensitivity, high-speed and automation, digital meter is produced and developed in this situation. There are many types of digital instruments, many classification methods, but in most cases is classified according to the use of the instrument (that is, the nature of the measured), such as electronic counters, digital phase