Methods and apparatus for improving voice quality in an environment with noise

Abstract

A method for improving a downlink signal received by a listener on a phone is disclosed. The method includes calculating an environment noise level of the listener and filtering and adjusting gain of the downlink signal based on the environment noise level.

1 . A method of improving a downlink signal received at a phone, comprising: 
 calculating an environment noise level at a phone receiving a downlink signal;    filtering the downlink signal to produce a filtered downlink signal; and    adjusting gain of the filtered downlink signal based on the environment noise level.    
   
   
       2 . The method of  claim 1 , further comprising producing an output signal at the phone, wherein the output signal is based on the filtered downlink signal and indicates a level of filtering based on the environment noise level.  
   
   
       3 . The method of  claim 1 , wherein the filtering reduces noise in the downlink signal.  
   
   
       4 . The method of  claim 1 , wherein the filtering reduces at least some low frequency content in the downlink signal relative to higher frequency content in the downlink signal.  
   
   
       5 . The method of  claim 1 , further comprising producing an output signal at the phone, wherein the output signal is based on the filtered downlink signal.  
   
   
       6 . The method of  claim 5 , wherein the output signal is based on a gain controller output that adjusts the gain of the downlink signal.  
   
   
       7 . The method of  claim 1 , further comprising delaying the downlink signal to the gain controller to produce a delayed downlink signal.  
   
   
       8 . The method of  claim 7 , further comprising: 
 adjusting gain of the delayed downlink signal based on the environment noise level; and    producing an output signal at the phone, the output signal based on the delayed downlink signal and the filtered downlink signal.    
   
   
       9 . The method of  claim 8 , wherein adjusting the gain of the delayed downlink signal is a function of adjusting the gain of the filtered downlink signal.  
   
   
       10 . The method of  claim 8 , wherein the producing the output signal includes combining the delayed downlink signal and the filtered downlink signal.  
   
   
       11 . The method of  claim 1 , wherein calculating the environment noise level includes taking a slow moving average of a noise level of the listener's uplink signal.  
   
   
       12 . The method of  claim 1 , wherein calculating the environment noise level includes taking a long time average of a noise level of the listener's uplink signal.  
   
   
       13 . The method of  claim 1 , wherein calculating the environment noise level includes employing a signal level averaging technique to determine an average of a noise level of the listener's uplink signal.  
   
   
       14 . An apparatus for improving a downlink signal received at a phone, comprising: 
 a noise level calculator to calculate an environment noise level at a phone;    a filter to receive a downlink signal and produce a corresponding filtered downlink signal; and    a gain controller, coupled to the filter and the noise level calculator, to receive the filtered downlink signal and adjust gain of the filtered downlink signal based on the environment noise level to produce a processed signal.    
   
   
       15 . The apparatus of  claim 14 , wherein the processed signal is a first processed signal, and wherein the gain controller receives the downlink signal and adjusts gain of the downlink signal based on the environment noise level to produce a second processed signal.  
   
   
       16 . The apparatus of  claim 15 , further comprising a delay line to delay the downlink signal received by the gain controller.  
   
   
       17 . The apparatus of  claim 15 , further comprising an adder coupled to the gain controller to add the first and second processed signals.  
   
   
       18 . The apparatus of  claim 15 , wherein the gain controller adjusts the gain of the filtered downlink signal inversely proportional to adjusting the downlink signal.  
   
   
       19 . The apparatus of  claim 14 , wherein the filter is a high pass filter.  
   
   
       20 . The apparatus of  claim 14 , wherein the filter is an FIR filter.  
   
   
       21 . The apparatus of  claim 14 , wherein the filter is an IIR filter.  
   
   
       22 . A computer readable storage medium storing instructions for improving a downlink signal received by a listener on a phone, wherein upon execution, the instructions instruct a processor to: 
 calculate an environment noise level at a phone receiving a downlink signal;    filter the downlink signal to produce a filtered downlink signal; and    adjust gain of the filtered downlink signal based on the environment noise level.    
   
   
       23 . The computer readable storage medium of  claim 22 , further comprising instructions to produce an output signal at the phone, the output signal based on the filtered downlink signal and having a level of filtering based on the environment noise level.  
   
   
       24 . The computer readable storage medium of  claim 22 , wherein the filtering reduces at least some low frequency content in the downlink signal relative to higher frequency content in the downlink signal.