Patent ID: 6933776

Claim:
A signal demodulating method of a two-phase frequency shift keying (FSK) digital demodulator, wherein said two-phase FSK digital demodulator receives an intermediate frequency (IF) signal, which is amplified, wave filtered, and synthesized, and then performs a demodulating step, said signal demodulating method comprising the following steps: detecting and collecting a positive edge signal and a negative edge signal of said intermediate frequency signal; selecting a corresponding threshold value in accordance with a different channel code and then receiving said positive edge signal as a switch signal to reset said threshold value as an initial value to start to count and compare to obtain a positive edge data bit; receiving said negative edge signal as a switch signal to reset said threshold value as an initial value to start to count and compare to obtain a negative edge data bit; and performing a frequency-descending decision step in accordance with said positive edge data bit and said negative edge data bit so as to send a base frequency signal.