Apparatus and method for compensating for varying adjacent channel conditions

1. An apparatus, comprising:

a digital signal source for providing a digital signal having a symbol rate;

a plurality of symbol shaping means;

amplifying means for amplifying said filtered digital signal to generate an amplified digital signal;

demodulating means for processing said amplified digital signal to obtain a demodulation lock; and

processing means for detecting if said demodulating means obtains said demodulation lock and causing said selected symbol shaping means to be selected responsive to said detection;

wherein a selected one of said symbol shaping means is used to filter said digital signal and generate a filtered digital signal based on said symbol rate.

2. The apparatus of claim 1 , wherein:

a first one of said symbol shaping means is used to filter said digital signal if said symbol rate is a first symbol rate;

a second one of said symbol shaping means is used to filter said digital signal if said symbol rate is a second symbol rate; and

a third one of said symbol shaping means is used to filter said digital signal if said symbol rate is a third symbol rate.

3. The apparatus of claim 2 , wherein:

said first symbol rate is approximately 0.772 MSym/S;

said second symbol rate is approximately 1.024 MSym/S; and

said third symbol rate is approximately 1.544 MSym/S.

4. The apparatus of claim 1 , further comprising:

digital AGC means for generating a digital AGC signal responsive to said amplified digital signal;

wherein said digital AGC signal is provided to said amplifying means.

5. The apparatus of claim 1 , further comprising:

analog filtering means for filtering an analog signal to generate a filtered analog signal including a desired channel corresponding to said digital signal and a portion of an undesired adjacent channel; and

wherein said selected symbol shaping means separates said desired channel from said undesired adjacent channel.

6. A method for performing signal processing, comprising:

receiving a digital signal having a symbol rate;

providing a plurality of symbol shaping filters;

amplifying said filtered digital signal to generate an amplified digital signal;

processing said amplified digital signal to obtain a demodulation lock;

detecting if said demodulation lock is obtained;

selecting said selected symbol shaping filter responsive to said detection; and

using a selected one of said symbol shaping filters to filter said digital signal and generate a filtered digital signal based on said symbol rate.

7. The method of claim 6 , further comprising:

using a first one of said symbol shaping filters to filter said digital signal if said symbol rate is a first symbol rate;

using a second one of said symbol shaping filters to filter said digital signal if said symbol rate is a second symbol rate; and

using a third one of said symbol shaping filters to filter said digital signal if said symbol rate is a third symbol rate.

8. The method of claim 7 , wherein:

said first symbol rate is approximately 0.772 MSym/S;

said second symbol rate is approximately 1.024 MSym/S; and

said third symbol rate is approximately 1.544 MSym/S.

9. The method of claim 6 , further comprising:

generating a digital AGC signal responsive to said amplified digital signal.

10. The method of claim 6 , further comprising:

filtering an analog signal to generate a filtered analog signal including a desired channel corresponding to said digital signal and a portion of an undesired adjacent channel; and

wherein said selected symbol shaping filter is used to separate said desired channel from said undesired adjacent channel.

11. A television signal receiver, comprising:

a digital signal source for providing a digital signal having a symbol rate;

a plurality of symbol shaping filters;

an amplifier operative to amplify said filtered digital signal to generate an amplified digital signal;

a demodulator operative to process said amplified digital signal to obtain a demodulation lock; and

a processor operative to detect if said demodulator obtains said demodulation lock and cause said selected symbol shaping filter to be selected responsive to said detection;

wherein a selected one of said symbol shaping filters is used to filter said digital signal and generate a filtered digital signal based on said symbol rate.

12. The television signal receiver of claim 11 , wherein:

a first one of said symbol shaping filters is used to filter said digital signal if said symbol rate is a first symbol rate;

a second one of said symbol shaping filters is used to filter said digital signal if said symbol rate is a second symbol rate; and

a third one of said symbol shaping filters is used to filter said digital signal if said symbol rate is a third symbol rate.

13. The television signal receiver of claim 12 , wherein:

said first symbol rate is approximately 0.772 MSym/S;

said second symbol rate is approximately 1.024 MSym/S; and

said third symbol rate is approximately 1.544 MSym/S.

14. The television signal receiver of claim 11 , further comprising:

a digital AGC operative to generate a digital AGC signal responsive to said amplified digital signal; and

wherein said digital AGC signal is provided to said amplifier.

15. The television signal receiver of claim 11 , further comprising:

an analog filter operative to filter an analog signal and generate a filtered analog signal including a desired channel corresponding to said digital signal and a portion of an undesired adjacent channel; and

wherein said selected symbol shaping filter is operative to separate said desired channel from said undesired adjacent channel.