Method for improving continuous phrase frequency shift key (CPFSK) signal carrier tracking precision

The invention discloses a method for improving a continuous phrase frequency shift key (CPFSK) signal carrier tracking precision, wherein the method is realized through the technical processes of performing rate reduction processing on a CPFSK signal by a re-sampling unit; performing Doppler information extraction on the rate-reduced CPFSK signal by a frequency discrimination branch circuit, an MSD decision feedback branch circuit and a (MSD+TPC) decision feedback branch circuit; analyzing the Doppler information by a Doppler analyzer, wherein the Doppler information is extracted by the three branch circuits, and obtaining an accurate Doppler estimated value; performing filtering on the Doppler estimated value by a loop filter and transmitting the filtered Doppler estimated value into a carrier numerically controlled oscillator (NCO), and generating a local carrier by the carrier NCO according to a carrier frequency and the Doppler estimated value; performing digital down conversion on an intermediate frequency signal by a down conversion device according to a local carrier, thereby realizing accurate tracking to the carrier by a loop. According to the method of the invention, Doppler information extraction is performed by means of the three branch circuits; and appropriate Doppler analysis algorithms can be selected according to different application scenes. The method of the invention can realize accurate Doppler estimation on condition of low signal-to-noise ratio and furthermore improves carrier tracking precision for the CPFSK signal.