Granted Patent B2

US 7,394,500 · App. 10/940,153 · Granted Jul 1, 2008

Abstract

Claims (85)

1. A television signal reception system comprising:

an analog to digital converter for:

receiving an intermediate frequency television signal; and

sampling said intermediate frequency television signal at a predetermined sampling frequency to produce a digitized television signal with a center frequency having an expected frequency offset from baseband, where said expected frequency offset is dependent upon a variant of a television standard according to which said intermediate frequency television signal is formatted;

a controller for providing an indication of said variant of said television standard for said intermediate frequency television signal;

a down converter including:

a first down converter frequency source for:

receiving said indication of said variant of said television standard from said controller;

selecting a frequency for a first mixing signal based on said indication of said variant of said television standard, where said frequency for said first mixing signal incorporates said expected frequency offset; and

a first down converter mixer for:

receiving said digitized television signal;

receiving said first mixing signal;

mixing down said digitized television signal with said first mixing signal to produce a mixed-down, digitized television signal with a center frequency near baseband; and

an image rejection filter for:

receiving said mixed-down, digitized television signal;

receiving said indication of said variant of said television standard;

selecting filter coefficients based on said indication of said variant of said television standard; and

filtering said mixed-down, digitized television signal according to said filter coefficients to produce a filtered digitized television signal;

a second down converter frequency source for:

receiving said indication of said variant of said television standard from said controller;

selecting a frequency for a second mixing signal based on said indication of said variant of said television standard; and

a second down converter mixer for:

receiving said filtered digitized television signal;

receiving said second mixing signal;

mixing said filtered digitized television signal with said second mixing signal to produce a mixed-up, digitized television signal with a video carrier frequency near baseband.

2. The television signal reception system of claim 1 further comprising a low pass video separation filter for filtering said mixed-up, digitized television signal to produce a digital video signal.

3. The television signal reception system of claim 1 wherein said low pass video separation filter is a finite impulse response digital filter.

4. The television signal reception system of claim 1 further comprising a high pass audio separation filter for filtering said mixed-up, digitized television signal to produce a digital audio signal.

5. The television signal reception system of claim 3 wherein said high pass audio separation filter is a finite impulse response digital filter.

6. The television signal reception system of claim 3 wherein a cut-off frequency for said low pass video separation filter is based on said predetermined sampling frequency.

7. The television signal reception system of claim 5 wherein a cut-off frequency for said high pass audio separation filter is equivalent to said cut-off frequency for said low pass video separation filter.

8. The television signal reception system of claim 6 further comprising:

a first separation filter frequency source for:

receiving said indication of said variant of said television standard; and

selecting a frequency for a first separation filter mixing signal based on said indication of said variant of said television standard; and

a first separation filter mixer for:

receiving said mixed-up, digitized television signal;

receiving said first separation filter mixing signal; and

mixing said mixed-up, digitized television signal with said first separation filter mixing signal to produce a digitized television signal with an audio signal having a frequency range with a minimum frequency, where said minimum frequency is greater than said cut-off frequency for said low pass video separation filter.

9. The television signal reception system of claim 7 further comprising:

a second separation filter frequency source for:

receiving said indication of said variant of said television standard; and

selecting a frequency for a second separation filter mixing signal based on said indication of said variant of said television standard; and

a second separation filter mixer for:

mixing said digital video signal with said second separation filter mixing signal to produce a digital video signal with said video carrier signal positioned within 50 Hz of baseband.

10. The television signal reception system of claim 4 further comprising:

a vestigial sideband filter for filtering said digital video signal with said video carrier signal near baseband to produce a complex digital video signal; and

a real component selector for selecting a real component of said complex digital video signal to produce a composite baseband video signal.

11. The television signal reception system of claim 1 further comprising a re-sampler for re-sampling said mixed-up, digitized television signal to produce a re-sampled, mixed-up, digitized television signal.

12. The television signal reception system of claim 1 further comprising:

a video carrier recovery circuit for:

receiving said mixed-up, digitized television signal;

detecting a phase offset of said video carrier;

generating a phase adjustment signal based on said phase offset;

a third down converter mixer for:

receiving said mixed-up, digitized television signal;

receiving said phase adjustment signal;

mixing said mixed-up, digitized television signal with said phase adjustment signal to produce a mixed-up, digitized television signal with a video carrier frequency nearer to baseband.

13. The television signal reception system of claim 12 wherein said video carrier recovery circuit is further for generating a frequency adjustment signal based on said phase offset.

14. The television signal reception system of claim 12 wherein said selecting said frequency for said first mixing signal is also based on said frequency adjustment signal.

15. A television signal reception method comprising:

sampling a received intermediate frequency television signal at a predetermined sampling frequency to produce a digitized television signal with a center frequency having an expected frequency offset from baseband, where said expected frequency offset is dependent upon a variant of a television standard of said received intermediate frequency television signal;

receiving an indication of said variant of said television standard;

selecting a frequency for a first mixing signal based on said indication of said variant of said television standard, where said frequency for said first mixing signal incorporates said expected frequency offset;

mixing down said digitized television signal with said first mixing signal to produce a mixed-down, digitized television signal with a center frequency near baseband;

selecting filter coefficients based on said indication of said variant of said television standard;

filtering said mixed-down, digitized television signal according to said filter coefficients to produce a filtered digitized television signal; and

processing said filtered digitized television signal to demodulate and decode said television signal.

16. A television signal reception system comprising:

an analog to digital converter for:

receiving an intermediate frequency television signal; and

sampling said intermediate frequency television signal at a predetermined sampling frequency to produce a digitized television signal with a center frequency having an expected frequency offset from baseband, where said expected frequency offset is dependent upon a variant of a television standard according to which said intermediate frequency television signal is formatted;

a controller for providing an indication of said variant of said television standard for said intermediate frequency television signal;

a frequency source for:

receiving said indication of said variant of said television standard; and

selecting a frequency for a mixing signal based on said indication of said variant of said television standard; and

a mixer for:

receiving said digitized television signal;

receiving said mixing signal; and

mixing said digitized television signal with said mixing signal to produce a mixed digitized television signal with an audio signal having a frequency range with a minimum frequency, where said minimum frequency is greater than a predetermined border frequency based on said predetermined sampling frequency; and

a low pass video separation filter for filtering said mixed digitized television signal to produce a digital video signal, wherein a cut-off frequency for said low pass video separation filter is equivalent to said predetermined border frequency.

17. The television signal reception system of claim 16 further comprising a high pass audio separation filter for filtering said digitized television signal to produce a digital audio signal.

18. The television signal reception system of claim 16 wherein a cut-off frequency for said high pass audio separation filter is equivalent to said cut-off frequency for said low pass video separation filter.

19. The method of claim 15 , wherein said processing further comprises further mixing said filtered digitized video signal to produce a baseband digitized television signal and decoding and demodulating said baseband digital television signal.

20. The method of claim 19 , wherein said processing further comprising separating said baseband digital television signal into digital audio and digital video signals.

Assignments (9)