Frequency measurement method based on FPGA

The invention provides a frequency measurement method based on an FPGA. A standard reference clock is adopted to count the number of pulses of a measured signal in a unit time (1s) and the number of the pulses of the measured signal in the unit time (1s) is the frequency of the signal. Due to the fact that the starting moment of a gate and the finishing moment of the gate are random for the signal, a pulse period quantization error can be produced, and measurement accuracy needs to be analyzed further: the pulse period of a signal to be measured is set to be Tx, the frequency is set to be Fx, and when the measuring time T equals to 1s, the measurement accuracy & meets the equation that &=Tx/T=1/Fx. The fact that measurement accuracy in a direct frequency measurement method is relevant to the frequency of the signal is known, the higher the frequency of the signal to be measured is, the higher the measurement accuracy is, and otherwise, the lower the frequency of the signal to be measured is, the lower the measurement accuracy is. The direct frequency measurement method is only suitable for measurement of the signal at the higher frequency and can not meet the demand that the measurement accuracy remains unchanged in the whole measurement frequency band. In order to overcome the defect of inaccuracy in low-frequency-band measurement, gating signals and the measured signal are used for carrying out dual control on enable signals of the counter, and therefore accuracy is improved.