Apparatus and method for echo indicator generation

Abstract

An echo indicator generation method, generating an echo indicator to indicate echo levels in a channel response of a transmission channel based on an input signal. The input signal comprises segment sync patterns repeating at intervals transmitted over the transmission channel. The input signal is filtered with a match filter having a filter response matched to the segment sync pattern to output a first signal. Thereafter, the first signal is periodically averaged to output a second signal. An echo indicator representing the echo levels of the transmission channel response is generated based on the second signal. Thus the echo level of the channel response is obtained.

1 . An echo indicator generation method for generating an echo indicator for indicating echo levels in a channel response of a transmission channel based on an input signal comprising segment sync patterns repeating at intervals transmitted over the transmission channel, comprising: 
 filtering the input signal with a match filter having a filter response matched to the segment sync pattern to output a first signal;    periodically averaging the first signal to output a second signal; and    generating an echo indicator representing the echo levels of the transmission channel response based on the second signal.    
   
   
       2 . The echo indicator generation method as claimed in  claim 1 , the step of generation comprising: 
 quantizing the strength of the second signal to obtain the echo indicator.    
   
   
       3 . The echo indicator generation method as claimed in  claim 2 , the quantizing levels are set relative to the maximal peak of the second signal within one period of data segment.  
   
   
       4 . The echo indicator generation method as claimed in  claim 1 , further comprising: 
 filtering the second signal with a post filter for sharpening the local maximal peaks of the second signal before being quantized.    
   
   
       5 . The echo indicator generation method as claimed in  claim 1 , wherein the step of accumulating the first signal comprises: 
 multiplying the first signal by a first constant to generate a third signal;    adding the third signal and a fourth signal to obtain a fifth signal;    delaying the fifth signal to obtain the second signal; and    multiplying the second signal by a second constant to generate the fourth signal; wherein    the first constant is greater than zero and less than unity and the second constant equals to the unity minus the first constant.    
   
   
       6 . An echo indicator generator, receiving an input signal comprising segment sync patterns repeating at intervals transmitted over a transmission channel, for indicating echo levels in a channel response of the transmission channel, comprising: 
 a match filter, having a filter response matched to the segment sync pattern for filtering the input signal to output a first signal;    an average unit for periodically averaging the first signal to output a second signal; and    a quantizer for generating an echo indicator representing the echo levels in the transmission channel response based on the second signal.    
   
   
       7 . The echo indicator generator as claimed in  claim 6 , wherein the quantizer generates the echo indicator by quantizing the strength of the second signal.  
   
   
       8 . The echo indicator generator as claimed in  claim 6 , wherein the quantizing levels are set relative to the maximal peak of the second signal within one period of data segment.  
   
   
       9 . The echo indicator generator as claimed in  claim 6 , further comprising: 
 a post filter, coupled between the average unit and the indicator generator, for sharpening the local maximal peaks of the second signal.    
   
   
       10 . The echo indicator generator as claimed in  claim 6 , wherein the average unit comprises: 
 a first multiplier, multiplying the first signal by a first constant to generate a third signal;    an adder, adding the third signal and a fourth signal to obtain a fifth signal;    a delay line, delaying the fifth signal to output the second signal; and    a second multiplier, multiplying the second signal by a second constant to generate the fourth signal; wherein    the first constant is greater than zero and less than unity and the second constant equals to the unity minus the first constant.