The Development Of The Low-cost And High-precision Frequency Meter By Broad-band Phase Coincidence Detection

This article mainly elaborated the low-cost and high-precision frequency meter's development goal and the plan to realize. This frequency-measuring meter designed depending on broad-band phase coincidence detection technology, it overcomes the±1 number count error and achieves high measurement precision on a wide frequency rage, and the cost maintains in the low level.This design has used a new phase coincide examination electric circuit, increased the precision of phase coincidence examination. The frequency standard changes from the external connection atom frequency standard to built-in high constant voltage control crystal oscillator, reduced the instrument cost. Moreover we increased the standard frequency calibration function, guaranteed to be able to obtain the very high test accuracy in the situation of use high constant voltage control crystal oscillator which have relatively high aging rate. In this research the phase coincide examination and the counting part were programming designed in the FPGA chip, which reduced the system order of complexity and the cost, enhanced the reliability, and strengthened the secrecy, and protected exploiter's intellectual property rights effectively. The FPGA chip used in this frequency meter is one chip of the Cyclone series made by ALTERA Corporation, developed by EDA tool QuartusⅡ6.0. The computation and the display work mainly complete by MCU, which selected is ATMEL Corporation's 89C51 single chip microcomputer of the MCS-51 series. Instrument's display mode uses the MCU control the liquid crystal module.The practice proved that this frequency meter has low cost, high accuracy, high integration rate and high reliability, can become one production face the market with the cooperation of factory.