Patent ID: 8184212

Claim:
A sound intermediate frequency (sound-IF) demodulator, adapted for an analog television (analog-TV) system and receiving a sound signal having at least one of a first carrier signal and a second carrier signal, wherein a sound de-matrix unit is adapted to generate a driving signal by de-matrixing outputs of the sound-IF demodulator, the sound-IF demodulator comprising: a first demodulating unit generating a first demodulated signal to the sound de-matrix unit by demodulating the first carrier signal; and a second demodulating unit detecting a signal quality of the sound signal and generating a second demodulated signal to the sound de-matrix unit and/or the first demodulating unit by demodulating the second carrier signal, wherein when the second demodulating unit is idle, the second demodulating unit is programmed to select a corresponding standard among a plurality of predetermined standards for the sound signal according to the signal quality of the sound signal, so that the sound-IF demodulator is programmed to demodulate the sound signal in the corresponding standard; and wherein the second demodulating unit comprises a first testing unit to detect a signal-to-noise ratio (SNR) and power of the first carrier signal and the second demodulator becomes idle when the SNR of the first carrier signal is larger than a first SNR threshold and the power of the first carrier signal is smaller than a power threshold.