Abstract:

To achieve the purpose of precision measuring signal frequency, we design a simple multi-function digital frequency meter with the fuction of measuring signal frequency, cycle, pulse width and duty ratio, using STC89C52 single-chip computer as the core controller, triode 3DG120, 74HC14 chip and 74HC4040 chip as the signal processing circuit, and present the unit module circuit and matching software. We put forward some anti-interference measures for the small-signal measurement. Experiments show that the system has achieved the design object, including its frequency measurement range for 1~50 MHz. The measuring error is less than 0.1% and the measuring small signal amplitude can be lower than 0.5 mV. It meets the testing requirements.

Key words: frequency counter, multiparameter measurement, multifunction, single-chip computer, small-signal