Abstract
With regard to the parameters measured frequency signal,the commonly used method is measuring the frequency of weeks or measurement. However, when the frequency of large changes, such as the range of 100 Hz ~ 100KHz, measuring frequency and method of measurement on the week there is a lot of limitations, difficult to achieve wide-band, high-precision measurements. So, when requires a method of measuring frequency to frequency changes in the scope of the larger signal of the high-precision measurement, it must be used, such as precision of measuring frequency technology.
The accuracy of the same frequency is a high-precision measurement can be measured the number of signal frequency measuring instruments. It has been widely used in aerospace, aviation, electronics, monitoring and control, automated measurement, and other fields. In this paper, such as use of precision measuring frequency of the principle, to meet the design, and other precision frequency of Objective: Altera Corporation production due to the complex programmable logic (CPLD) EPM7128 with speed and precision timing, and other characteristics at the same time, because of the need to involve the countdown Computing (frequency and cycle countdown relationship to each other), and SCM AT89C51 numerical computing in a very easy and convenient. Therefore, the main hardware from the above two parts. Software, using VHDL language programming in MAX + PLUSII CPLD completed by the middle of the software design, build, debug, simulation and download; compilation of language used in the simulator-fu (wave), the entire circuit test signal control, data operations With the keyboard scanning and digital control of the simulation, including SCM AT89C51 is the main control system components.
System, using decimal figures show that the realization of measurement sine wave, square-wave signals, a sharp pulse of the frequency of the cycle, and other basic functions, CPLD and SCM integration, learning from, so as to achieve the best results.
Keywords:Equal precision frequency meters CPLD VHDL The show circuit