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1、、学位论文英文翻译英文原文：Introduction of digital frequency meterDigital 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
2、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 kin
3、ds: (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 pri
4、nciples 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 regio
5、n 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 Signa
6、ls 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-fre
7、quency, 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 automatic conversion range, and expanded the range of frequency measurement; realization of the entire scope of measurement a
8、ccuracy, reduce the low-frequency measurement error. The design of the main methods of measuring the frequency measurement and control block diagram as shown in Figure 1. Figure 1 Preferences gated signal GA TE issued by the MCU, GA TE time width of less frequency measurement accuracy, in the larger
9、 context of choice, as long as the FPGA in 32 of 100 in the counter b M signal Overflow will do, according to theoretical calculations GA TE time width T c can be greater than 42194 s, but due to the single-chip microcomputer data processing capacity constraints, the actual width of less time, gener
10、ally 10 to 011 s in the inter-choice, that is, high - band, the gate time shorter, low gate longer. This time gate width based on the measured T c automatically adjust the size of frequency measurement frequency range to achieve the automatic conversion, and expanded the range of frequency measureme
11、nt; realization of the entire scope of measurement accuracy, reduce the low-frequency measurement error.2 Frequency of achievingFrequency Measurement accuracy of such method. Can be simplified as shown in the diagram. Map CNT1 and CNT2 two controllable counter, standard frequency (f) signal from the
12、 CN F1 clock input cI K input, the signal measured after the plastic (f) CNT2 clock input cI K input. Each counter in the CEN input as enable end, used to control the counter count. When the gate signal is HIGH Preferences (Preferences start time). Signal measured by the rising edge of the D flip-fl
13、op input, launched at the same time with two counts of juice; Similarly, when preferences for low gate signal (the end of Preferences time), the rising edge of the measured signals through D Trigger output end of the counter to stop counting.3And the median frequency of relevant indicatorsMedian: At
14、 the same time the figures show that up to the median. The usual eight-count frequency of only several hundred yuan can buy. For high precision measurements, nine just beginning, the middle is 11, 13 can be relatively high. Overflow of:-the ability to promote itself to overflow the equivalent of the
15、 total. Some of the frequency with overflow function, which is the highest overflow does not display only shows that the bit behind, in order to achieve the purpose of the median. Here is the estimated value of individual indicators. Speed: namely, the number of per second. With the high number of m
16、easurement particularly slow but also lose its significance. Counting of the usual eight frequency measurement 10 MHz signals, one second gate will be 10000000 Hz, which is actually seven (equivalent to the median number of common admission after the value), to obtain eight needed 10 seconds gate ; to obtain nine needed 100 seconds gate, followed by analogy, shows that even the permission of 11 need 10,000 second measurement time. But in
