数字频率计介绍外文翻译.docVIP

学位论文英文翻译 英文原文： Introduction of digital frequency meter Digital Frequency of communications equipment, audio and video, and other areas of scientific research and production of an indispensable instrument. Programming using Verilog HDL Design and Implementation of the digital frequency, in addition to the plastic part of the measured signal, and digital key for a part of the show, all in an FPGA chip to achieve. The entire system is very lean, flexible and have a modification of the scene. 1 And other precision measuring frequency Principle. Frequency measurement methods can be divided into two kinds:  (1) direct measurement method, that is, at a certain time measurement gate measured pulse signal number.  (2) indirect measurements, such as the cycle frequency measurement, VF conversion law. Frequency Measurement indirect measurement method applies only to low-frequency signals. Based on the principles of traditional frequency measurement of the frequency of measurement accuracy will be measured with the decline in signal frequency decreases in the more practical limitations, such as the accuracy and frequency of measurement not only has high accuracy, but also in the whole frequency region to maintain constant test accuracy. The main method of measurement frequency measurement Preferences gated signal GATE issued by the MCU, GATE time width on the frequency measurement accuracy of less impact, in the larger context of choice, as long as the FPGA in 32 of 100 in the counter b M Signals are not overflow line, in accordance with the theoretical calculation GATE time can be greater than the width Tc 42.94 s, but due to the single-chip microcomputer data processing capacity constraints, the actual width of less time, generally in the range of between 0.1 s choice, that is, high-frequency, shorter gate;, low gate longer. This time gate width Tc based on the size of the measured frequency automatically adjust frequency measurement in order to achieve the automati