The present invention relates to an instantaneous frequency extraction method of Doppler signals, and belongs to the
signal processing technology field. According to the present invention, for the Doppler signals outputted by various interference velocimeters, firstly the appropriate parameters, such as the
wavelet, the threshold type, the
decomposition layer number, the vanishing moment, etc., are selected to carry out the
wavelet de-noising on the output signals to smooth the edges; after then the
amplitude modulation-
frequency modulation decomposition is carried out on the de-noised signals in an iteration manner, and the envelopes of the signals are extracted and are normalized; and finally, the instantaneous frequencies of the normalized signals are extracted by a direct
orthogonal method, and an
estimation curve of the instantaneous frequencies is obtained in a least-square fitting manner. According to the present invention, firstly the signals are de-noised, so that the direct
orthogonal method which is more sensitive to the
noise originally can be applied to the Doppler signals, and the
simulation results show that on the condition of selecting the appropriate parameters, an error of an instantaneous frequency value obtained by the present invention and a theoretical value is less than 0.5%, the calculation time and the sampling point number are positively related, and the calculation velocity is faster.