Apparatus and method for rejecting co-channel interference signal

Abstract

Methods and television receivers for rejecting a co-channel interference signal from a first digital signal. A first digital signal is delayed to output a first delayed signal. In this method, an synthesized interference signal is generated based on the first digital signal. The synthesized interference signal is subtracted from the first delayed digital signal and produces a second digital signal. The second digital signal is equalized to output an equalized signal based on a first decision signal. The equalized signal is decoded to output the first decision signal. The equalized signal is delayed to output a second delayed signal. A compensation signal is generated based on the first decision signal. The compensation signal is subtracted from the delayed second signal and produces a fifth digital signal serving as an output signal.

1 . A receiver capable of rejecting a co-channel interference signal from a first digital signal, the receiver comprising:
 an interference rejection unit, for removing the co-channel interference signal from the first digital signal to output a second digital signal;   an equalization unit, for equalizing the second digital signal to generate a first equalized signal, and compensating the first equalized signal to generate a second equalized signal according to a first decision signal;   a first decision unit, for generating the first decision signal according to the second equalized signal; and   a compensation unit, for compensating the second equalized signal to generate an output signal according to the first decision signal.   
   
   
       2 . The receiver as claimed in  claim 1 , wherein the interference rejection unit comprises a synthesis filter and the compensation unit comprises a compensation filter, and coefficients of the compensation filter are set according to that of the synthesis filter. 
   
   
       3 . The receiver as claimed in  claim 1 , wherein the co-channel interference signal is a NTSC signal and the first digital signal is a digital television signal. 
   
   
       4 . The receiver as claimed in  claim 1 , wherein the equalization unit comprises:
 a linear equalizer, for receiving the second digital signal to generate the first equalized signal;   a decision feedback equalizer, for receiving the first decision signal and a second decision signal generated according to the output signal to generate a third digital signal; and   an adder, for adding the third digital signal to the first equalized signal to generate the second equalized signal.   
   
   
       5 . The receiver as claimed in  claim 1 , wherein the compensation unit comprises:
 a delay unit, for delaying the second equalized signal to output a delayed signal;   a compensation filter, for generating a compensating signal according to the first decision signal; and   a subtracting unit, for subtracting the compensating signal from the delayed signal to generate the output signal.   
   
   
       6 . The receiver as claimed in  claim 1 , wherein the interference rejection unit comprises:
 a delay unit, for delaying the first digital signal to generate a delayed signal;   a synthesis filter, for generating a synthesized co-channel interference signal according to the first digital signal; and   a subtracting unit, for subtracting the synthesized co-channel interference signal from the delayed signal to generate the second digital signal.   
   
   
       7 . The receiver as claimed in  claim 1 , wherein the first decision unit is a slicer. 
   
   
       8 . The receiver as claimed in  claim 4 , further comprising a second decision unit to generate the second decision signal according to the output signal. 
   
   
       9 . The receiver as claimed in  claim 8 , wherein the second decision unit is a slicer. 
   
   
       10 . The receiver as claimed in  claim 8 , wherein the second decision unit is an error correction decoder. 
   
   
       11 . A method for rejecting a NTSC signal from a digital television signal, the method comprising:
 removing the NTSC signal from the digital television signal to generate a digital signal;   equalizing the digital signal to generate an equalized signal by decision feedback equalization according to a first decision signal;   slicing the equalized signal to generate the first decision signal;   filtering the first decision signal to obtain a compensation signal; and   removing the compensation signal from the equalized signal to generate an output signal.   
   
   
       12 . The method as claimed in  claim 11 , further comprising:
 slicing the output signal to generate a second decision signal; and   equalizing the digital signal to generate the equalized signal by the decision feedback equalization according to the first and second decision signals.   
   
   
       13 . The method as claimed in  claim 12 , wherein the decision feedback equalization is performed with a set of coefficients, and the coefficients are optimized by the first and second decision signals. 
   
   
       14 . The method as claimed in  claim 11 , wherein the step of removing the NTSC signal from the digital television signal utilizes a synthesis filter, the step of filtering the first decision signal to obtain the compensation signal utilized a compensation filter, and coefficients of the compensation filter are set according to that of the synthesis filter. 
   
   
       15 . A method of rejecting co-channel interference signal from a first digital signal, comprising:
 filtering the co-channel interference signal from the first digital signal to obtain a second digital signal distorted by a first channel response;   equalizing the second digital signal to obtain a third digital signal by decision feedback equalization, wherein the decision feedback equalization is performed according to a first decision signal;   slicing the third digital signal to obtain the first decision signal;   filtering the first decision signal to generate a fourth digital signal distorted by a second channel response for compensating the first channel response; and   combining the third digital signal and the fourth digital signal to obtain an output signal.   
   
   
       16 . The method as claimed in  claim 15 , further comprising:
 slicing the output signal to obtain a second decision signal, such that the decision feedback equalization is performed according to the first and second decision signals and.   
   
   
       17 . The method as claimed in  claim 16 , wherein the decision feedback equalization is performed with a set of coefficients, and the set of coefficients are optimized by the first and second decision signals. 
   
   
       18 . The method as claimed in  claim 15 , wherein the first decision signal is filtered according to a first set of coefficients determined by a second set of coefficients for filtering the co-channel interference signal. 
   
   
       19 . The method as claimed in  claim 15 , wherein the co-channel interference signal is a NTSC signal and the first digital signal is a digital television signal.