Digital implementation of analog TV receiver

1. An analog television receiver comprising a demodulator for demodulating a received analog television signal and producing a demodulated television signal, an analog to digital converter for processing the demodulated television signal and digitizing the demodulated television signal, thereby producing a digitized television signal, and a digital signal processor for processing the digitized television signal and producing display signals from the digitized television signal, the digital signal processor being programmed to:

search for a horizontal synchronization signal in the television signal;

track the horizontal synchronization signal using a delay locked loop;

search for a vertical synchronization signal in the digitized television signal using the horizontal synchronization signal;

separate a luminance and a pair of chrominance components of the digitized television signal;

demodulate the pair of chrominance components;

construct red, green and blue values from the demodulated chrominance components and the luminance components; and

produce display signals from the red, green and blue values.

2. The receiver according to claim 1 , wherein the vertical synchronization signal is maintained by using the tracked horizontal synchronization signal.

3. The receiver according to claim 1 , wherein the horizontal synchronization signal is continuously tracked at least after horizontal synchronization has been obtained.

4. The receiver according to claim 1 , wherein the horizontal synchronization signal tracking includes determining an average timing offset and using the average timing offset to track changes from the average timing offset via the delay locked loop.

5. The receiver according to claim 1 , wherein the delay locked loop is disabled during a vertical synchronization period.

6. The receiver according to claim 1 , wherein the horizontal synchronization signal tracking must persist for about twenty lines to be valid.

7. The receiver according to claim 1 , wherein the program determines scaling gain as a function of a low pulse level and a blanking level of the vertical synchronization signal, determines DC level as a function of the scaling gain and the blanking level of the vertical synchronization signal, and adjusts the television signals as a function of the scaling gain and the DC level.

8. The receiver according to claim 1 , wherein the program determines a phase of the chrominance components which are used in the demodulation of the chrominance components.

9. The receiver according to claim 1 , wherein the program determines the phase of the chrominance components from a color burst as

ChromaPhase( k )=a tan 2(color_burst_sample( k ),color_burst_sample( k+ 1)).

10. The receiver according to claim 1 , wherein the receiver is a mobile communication device with a display.

11. The receiver according to claim 1 , wherein the horizontal synchronization signal search includes computing a moving average over a line length and using the moving average to determine a horizontal synchronization match.

12. The receiver according to claim 11 , wherein the moving average is spread over N lines with 1/Nth of each line moving 1/N samples per line being used for the average.

13. The receiver according to claim 1 , wherein the vertical synchronization signal search includes performing a partial match over at least three lines, and summing the partial matches to determine a vertical synchronization match.

14. The receiver according to claim 1 , wherein the program determines the phase of the chrominance components from a color burst as

ChromaPhase( k )=a tan 2(imag( X (6),real( X (6)).