Patent ID: 8416347
Filing Date: 2013-04-09
Classification: H04N

Abstract:
1. A method of automatically selecting audio format for output signal of a tuner in a television system, the method comprising the steps of: (A) a video surface acoustic wave (SAW) filter converting a first intermediate frequency (IF) signal outputted by the tuner into a video intermediate frequency (VIF) signal based on a first configured bandwidth configured by a controller; an audio SAW filter converting the first IF signal into an sound intermediate frequency (SIF) signal under control of the controller; a demodulator demodulating the VIF signal to obtain a composite video baseband signal (CVBS) and demodulating the SIF signal to obtain a second sound intermediate frequency (SSIF) signal under control of the controller; (B) a video decoder having a first band-pass filter and a second band-pass filter simultaneously filtering the CVBS signal based on a center frequency configured by the controller, wherein the center frequency of the first band-pass filter is greater than the center frequency of the second band-pass filter; (C) the controller determining whether the CVBS signal at the center frequency of the first band-pass filter has a signal amplitude greater than that of the second band-pass filter, and executing step (D) when the CVBS signal at the center frequency of the first band-pass filter has the signal amplitude greater than that of the second band-pass filter, otherwise executing step (E); (D) the controller controlling the first band-pass filter to detect a signal amplitude of the CVBS signal at a synchronous tip and a back porch and determining whether the signal amplitude of the CVBS signal at the back porch is greater than that at the synchronous tip, the video decoder being controlled by the controller to decode a received CVBS signal and to select one of NTSC443, PAL, and SECAM formats as a video format of the CVBS signal when the signal amplitude of the received CVBS signal at the back porch is greater than that at the synchronous tip, and an audio decoder being controlled by the controller to decode a received SSIF signal and to select one of BG, DK, and I formats as an audio format of the received SSIF signal when the signal amplitude of the received CVBS signal at the back porch is greater than that at the synchronous tip, otherwise executing step (F); (E) the video surface acoustic wave (SAW) filter converting the first intermediate frequency (IF) signal outputted by the tuner into the video intermediate frequency (VIF) signal based on a second configured bandwidth configured by the controller and decoding a second received CVBS signal to select one of NTSC, PAL-M, and PAL-N formats as a video format of the second received CVBS signal under control of the controller, and the audio decoder decoding a second received SSIF signal to select one of M, BG, DK, and I formats as an audio format of the second received SSIF signal under control of the controller; and (F) the video SAW filter converting the first IF signal outputted by the tuner into the VIF signal based on the second configured bandwidth, the video decoder decoding the second received CVBS signal to select one of NTSC, PAL-M, and PAL-N formats as the video format of the second received CVBS signal under control of the controller, the audio decoder decoding the second received SSIF signal to select one of M and N formats as the audio format of the second received SSIF signal under control the controller.