Measuring method of virtual digital phase locking for phase modulation laser doppler frequency parameter

The virtual digital phase locking technique based on LabView visual language is proposed to measure the frequency parameter of phase modulation laser Doppler shift measuring method, and investigate it theoretically and experimentally. For preventing the disturbance between the test signal and the reference signal channels and mixed with noise in the process of reference signal transmission, this virtual digital phase locking technique adopts the method of reference signal generated inside. In order to ensure the same frequency between reference signal and test signal for accurate frequency parameter measurements, the virtual digital phase locking loop for accurately capturing the test signal frequency is introduced into the virtual digital phase locking technique. The validity and feasibility of the virtual digital phase locking frequency parameter measuring method are proved through measuring the practical phase modulation beat signal.