Heterodyne Frequency Measurement Method Based on Virtual Instrument

The heterodyne method is one of main methods in high precision frequency measurement. In the traditional heterodyne method, the counter is used to measure the square wave of beat signal. This method is inconvenient to the multi-chaneel measurement and real-time display of measurement results. In this paper, based on the technique of virtual instruments, the traditional heterodyne method is improved. The Analog Digital Converter and computer are used to replace counter. The sine wave of beat signal is converted into digital signal with ADC. The digital signal will be analyze by computer, its frequency calculated by the digital signal processing. This method is convenient for the multi-channel measurement and the real-time display of measure results. This method compared with the traditional heterodyne method, it is better than the traditional method in accuracy.