Digital television signal processing system including a co-channel rejection filter

• US 5,550,596 A
• Filed: 11/25/1994
• Issued: 08/27/1996
• Est. Priority Date: 11/25/1994
• Status: Expired due to Term

• Current Assignee: Thomson Multimedia SA (Vantiva SA)
• Original Assignee: Thomson Multimedia SA (Vantiva SA)
• Inventors: Jaffe, Steven T., Strolle, Christopher H.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): MURRELL, JEFFREY S
• Application Number:
  US08/345,031
• Time in Patent Office: 641 Days
• Field of Search: 348/21, 348/607, 348/471, 348/608, 348/609, 348/611, 348/726, 348/725, 375/316, 375/229, 375/230, 375/233, 375/355
• US Class Current: 348/607
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/0307 using blind adaptation
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 5/21 Circuitry for suppressing or minimising disturbance, e.g. moiré or halo

Abstract

A digital signal proces sing system for receiving and processing a high definition television signal, eg., in a Pulse Amplitude Modulation (PAM) format, includes a filter for rejecting interferer signals such as a narrowband continuous wave NTSC co-channel interferer. In an illustrated embodiment the rejection filter is a digital FIR filter (18) located after a (de)rotator (16) in a carrier recovery network (16, 20, 24, 26, 28). The filter exhibits a zero throughput delay bandpass response with attenuation notches for rejecting NTSC co-channel picture and chrominance baseband carrier frequencies.

Claims

1. In a television receiver for receiving a television signal representative of digital video information, apparatus comprising:

an input signal translation network;

a first equalizer responsive to signals from said signal translation network;

a baseband demodulator responsive to an output signal from said equalizer; and

a notch filter included in said baseband demodulator for filtering baseband and near-baseband video signals, said filter exhibiting a response including significant amplitude attenuation at a prescribed frequency for attenuating interferer signal components subject to contaminating said received signal.

2. Apparatus according to claim 1 and further comprising a second equalizer responsive to signals produced by said demodulator after filtering by said notch filter.

3. Apparatus according to claim 1, wherein

said notch filter is a FIR digital filter for attenuating co-channel interferer signals at picture carrier and chrominance carrier frequencies;

and

said signal translation network is a frequency converter.

4. Apparatus according to claim 3, wherein said notch filter exhibits an upper bandedge excess frequency region encompassing a co-channel sound carrier frequency.

5. In a system for receiving a signal representative of digital video information, apparatus comprising:

an input processor;

an input equalizer responsive to signals from said input processor;

a carrier recovery network responsive to an output signal from said equalizer for providing a demodulated baseband video signal;

an output signal processor for processing said baseband video signal; and

a filter included in said carrier recovery network for filtering baseband and near-baseband video signals, said filter exhibiting a response including significant amplitude attenuation at a prescribed frequency for attenuating .narrowband interferer signal components subject to contaminating said received signal.

6. Apparatus according to claim 5, wherein said filter is a digital FIR filter exhibiting substantially zero throughput delay.

7. Apparatus according to claim 5, wherein

said received signal is a television signal subject to being contaminated by co-channel interference;

and

said filter provides significant attenuation at NTSC picture carrier and chrominance carrier frequencies.

8. In a system for receiving a signal representative of digital video information, apparatus comprising:

an input processor;

an input equalizer responsive to signals from said input processor;

a carrier recovery network responsive to an output signal from said equalizer for providing a demodulated baseband video signal;

an output signal processor for processing said baseband video signal; and

a filter included in said carrier recovery network for filtering baseband and near-baseband video signals, said filter exhibiting a response including significant amplitude atenuation at a prescribed frequency for attenuating narrowband interferer signal components subject to contaminating said received signal;

wherein

said carrier recovery network comprises a feedback control loop including said filter.

9. In a system for receiving a signal representative of digital video information, apparatus comprising:

an input processor;

an input equalizer responsive to signals from said input processor;

a carrier recovery network responsive to an output signal from said equalizer for providing a demodulated baseband video signal;

an output signal processor for processing said baseband video signal; and

a filter included in said carrier recovery network for filtering baseband and near-baseband video signals, said filter exhibiting a response including significant amplitude attenuation at a prescribed frequency for attenuating narrowband interferer signal components subject to contaminating said received signal;

wherein

said carrier recovery network includes a slicer with an input for receiving signals from said filter, and an output; and

a decision feedback equalizer has an input for receiving output signals from said slicer and an output coupled to a point in said carrier recovery network prior to said slicer.

10. In a system for receiving a signal representative of digital video information, apparatus comprising:

an input processor;

an input equalizer responsive to signals from said input processor;

a carrier recovery network responsive to an output signal from said equalizer for providing a demodulated baseband video signal;

an output signal processor for processing said baseband video signal; and

a filter included in said carrier recovery network for filtering baseband and near-baseband video signals, said filter being a digital FIR filter with substantially zero throughput delay and exhibiting a response including significant amplitude attenuation at a prescribed frequency for attenuating narrowband interferer signal components subject to contaminating said received signal;

wherein said carrier recovery network includes

a rotator responsive to output signals from said equalizer;

a slicer responsive to output signals from said rotator;

an error detector coupled to said slicer for providing an output error signal representing a phase error; and

a phase control network responsive to input and output signals of said slicer; and

wherein

said filter is coupled between said rotator and said slicer for filtering output signals from said rotator.

11. In a system for receiving a television signal including a component representative of digital video information, apparatus comprising:

an input processor;

a feed-forward equalizer responsive to signals from said input processor; and

a carrier recovery network responsive to an output signal from said equalizer for providing a demodulated baseband video signal, said carrier recovery network comprising a carrier recovery control loop including

(a) a rotator responsive to output signals from said forward equalizer;

(b) a filter for filtering output signals from said rotator, said filter exhibiting significant attenuation of at least one of baseband picture carrier and chrominance carrier frequencies;

(c) a slicer responsive to output signals from said filter;

(d) an error detector coupled to said slicer for providing a phase error signal; and

(e) a phase control network having an input responsive to an output signal from said slicer, and an output coupled to said rotator.

12. Apparatus according to claim 11 and further including

a feedback equalizer having a signal input responsive to an output signal from said slicer, a control input responsive to said error signal, and an output coupled to an input of said slicer;

and wherein

said feed-forward equalizer is also responsive to said error signal.

13. Apparatus according to claim 11, wherein

said received television signal is a Pulse Amplitude Modulated (PAM) signal.