FSK/GFSK demodulator with digital frequency offset compensation and the demodulating method of the same

摘要

The present invention discloses an FSK/GFSK demodulator with digital frequency offset compensation, comprising: an FSK/GFSK signal demodulator, for receiving a transmission signal from an antenna and generating an inter-medium frequency (base-frequency) signal after amplification and filtering; an analog-to-digital converter (ADC), for receiving the inter-medium frequency (base-frequency) signal from the FSK/GFSK signal demodulator and converting the signal into a digital signal; a digital frequency discriminator, for receiving the digital signal from the analog-to-digital converter and generating a discriminated signal; a digital band-pass filter, for filtering off a high-frequency component and a DC component of the discriminated signal and generating a demodulated signal; and a data slicer, for receiving the demodulated signal and generating a received signal. The digital band-pass filter is composed of a digital low-pass filter and a digital high-pass filter connected in series. The FSK/GFSK demodulator with digital compensation for frequency offset according to the present invention employs a digital filter unit to filter off the direct-current (DC) component of the frequency offset of the discriminated signal, and generates a demodulated signal independent of the DC component of the frequency offset. Therefore, the data slicer can correctly determine the demodulated signal without the DC level.