Television signal receiver capable of cancelling linear and non-linear distortion
A television signal receiver comprises: a tuner, an optional IF conditioner, an IF distortion canceller, and an IF demodulator. The tuner selects one channel from a radio frequency television signal to generate an intermediate frequency signal. The IF conditioner outputs an IF conditioned signal. The IF distortion canceller cancels a signal distortion in the IF signal or the IF conditioned signal to generate an IF distortion-cancelled signal. The IF demodulator demodulates the IF distortion-cancelled signal to output a baseband signal.
1. A television signal receiver, comprising:
a tuner for selecting one channel from a radio frequency (RF) television signal to generate an intermediate frequency (IF) signal;
an IF distortion canceller coupled to the tuner for canceling a signal distortion in the IF signal to generate an IF distortion-cancelled signal, wherein the IF distortion canceller comprises a front-end portion having an input to receive the IF signal and cancel non-linear distortion in the IF signal, wherein the IF distortion canceller further comprising a back-end portion having an input to receive an output of the front-end portion and cancel linear distortion carried in the IF signal, the back-end portion outputting the IF distortion-cancelled signal; and
an IF demodulator coupled to the IF distortion canceller for demodulating the IF distortion-cancelled signal to output a baseband signal.
2. The television signal receiver as claimed in claim 1 , wherein the IF distortion canceller comprises:
non-linear distortion canceling circuitry operated at an IF band for canceling the non-linear distortion in the IF signal.
3. The television signal receiver as claimed in claim 2 , wherein the non-linear distortion canceling circuitry comprises:
a level-mapping device having a programmable transfer curve for canceling a tuner transfer curve distortion.
4. The television signal receiver as claimed in claim 1 , wherein the IF distortion canceller comprises:
linear distortion canceling circuitry operated at an IF band for canceling the linear distortion in the IF signal.
5. The television signal receiver as claimed in claim 4 , wherein the linear distortion canceling circuitry comprises:
an amplitude distortion canceller having a programmable amplitude response for canceling an amplitude response distortion;
wherein the amplitude response distortion comprises a tuner amplitude response from the tuner.
6. The television signal receiver as claimed in claim 4 , wherein the linear distortion canceling circuit comprises:
a programmable filter having a programmable group delay for canceling a group delay distortion;
wherein the group delay distortion comprises a group delay precorrection performed by a transmitter, and a tuner group delay from the tuner.
7. The television signal receiver as claimed in claim 4 , wherein the linear distortion canceling circuitry comprises:
a programmable digital filter having a programmable amplitude response and a programmable group delay for canceling an amplitude response distortion and a group delay distortion;
wherein the amplitude response distortion comprises an amplitude response distortion from the tuner;
wherein the group delay distortion comprises a group delay precorrection performed by a transmitter, and a tuner group delay form the tuner.
8. The television signal receiver as claimed in claim 1 further comprising:
a controller coupled to the IF distortion canceller for generating a control signal to program the IF distortion canceller to cancel distortion in the IF signal.
9. A television signal receiver, comprising:
a tuner for selecting one channel from a radio frequency (RF) television signal to generate an intermediate frequency (IF) signal;
an IF conditioner coupled to the tuner for conditioning the IF signal to generate an IF conditioned signal;
an IF distortion canceller coupled to the IF conditioner for canceling a signal distortion in the IF conditioned signal to generate an IF distortion-cancelled signal, wherein the IF distortion canceller comprises a front-end portion having an input to receive the IF conditioned signal and cancel non-linear distortion in the IF signal, wherein the IF distortion canceller further comprising a back-end portion having an input to receive an output of the front-end portion and cancel linear distortion carried in the IF signal, the back-end portion outputting the IF distortion-cancelled signal; and
an IF demodulator coupled to the IF distortion canceller for demodulating the IF distortion-cancelled signal to output a baseband signal.
10. The television signal receiver as claimed in claim 9 , wherein the IF conditioner comprises:
an IF filter for filtering the IF signal.
11. The television signal receiver as claimed in claim 9 , wherein the IF conditioner comprises:
an amplifier for adjusting a signal power level of the IF signal.
12. The television signal receiver as claimed in claim 9 , wherein the IF conditioner comprises:
a quantizer for digitizing the IF signal.
13. The television signal receiver as claimed in claim 9 , wherein the IF conditioner comprises:
a frequency shifter for moving a signal spectrum of the IF signal to an IF band in a predetermined depth.
14. The television signal receiver as claimed in claim 9 , wherein the IF distortion canceller cancels a signal distortion generated by the IF conditioner.
15. A method of receiving a radio frequency (RF) signal, comprising:
selecting one channel from the RF signal to generate an intermediate frequency (IF) signal;
canceling a non-linear signal distortion in the IF signal to generate an intermediate conditioned signal;
canceling a linear signal distortion in the intermediate conditioned signal to generate an IF distortion-cancelled signal; and
demodulating the IF distortion-cancelled signal to output a baseband signal.
16. The method as claimed in claim 15 , wherein the step of canceling the non-linear signal distortion comprises:
canceling an amplifier transfer curve distortion.
17. The method as claimed in claim 15 , wherein
canceling the linear signal distortion comprises canceling an amplitude response distortion; and
canceling a group delay distortion;
wherein the group delay distortion comprises a group delay precorrection and a selecting group delay introduced during the step of selecting one channel from the RF television signal.
18. A method of receiving a radio frequency (RF) signal, comprising:
selecting one channel from the RF signal to generate an intermediate frequency (IF) signal;
conditioning the IF signal to generate an IF conditioned signal;
canceling a non-linear signal distortion in the IF conditioned signal to generate an intermediate conditioned signal;
canceling a linear signal distortion in the intermediate conditioned signal to generate an IF distortion-cancelled signal; and
demodulating the IF distortion-cancelled signal to output a baseband signal.
19. The method as claimed in claim 18 , wherein the step of conditioning the IF signal comprises:
filtering the IF signal.
20. The method as claimed in claim 18 , wherein the step of conditioning the IF signal comprises:
adjusting a signal power level of the IF signal.
21. The method as claimed in claim 18 , wherein the step of conditioning the IF signal comprises:
digitizing the IF signal.
22. The method as claimed in claim 18 , wherein the step of conditioning the IF signal comprises:
moving a signal spectrum of the IF signal to an IF band in a predetermined depth.