System and method for split automatic gain control

Abstract

A system and method for automatically controlling gain in a signal chain are presented. A first signal is processed to produce a processed signal. A gain is adjustably applied to the processed signal using an automatic gain control (AGC) mechanism. A resulting signal is produced. The gain is adjusted based on the first signal. As such, even when a desired signal is not substantially present in the first signal, gain is not excessively applied to the processed signal.

1 . A method for automatically controlling gain in a signal chain, comprising:
 attenuating an undesired signal in an input signal received at a processing circuitry to produce a processed signal, said input signal comprising at least one of a desired signal and said undesired signal;   adjustably applying a gain to the processed signal of said processing circuitry to produce a resulting signal, wherein the gain is adjusted based only on the input signal input to the processing mechanism.   
   
   
       2 . The method of  claim 1 , wherein the desired signal and the undesired signal have approximately equal orders of magnitude. 
   
   
       3 . The method of  claim 1 , wherein attenuating the undesired signal does not substantially affect the desired signal. 
   
   
       4 . The method of  claim 1 , wherein the desired signal is not substantially present in the unprocessed input signal, and wherein the adjustably applying the gain comprises increasing the gain applied to the processed signal. 
   
   
       5 . The method of  claim 2 , wherein the desired signal represents a voice signal and wherein the undesired signal represents an echo of a tone. 
   
   
       6 . The method of  claim 5 , wherein the input signal is generated by a recording device. 
   
   
       7 . A system comprising:
 a processing circuitry configured to receive an input signal comprising at least one of a desired signal and an undesired signal, said processing circuitry comprising a filter configured to attenuate said undesired signal; and   an automatic gain controller (AGC) configured to adjustably apply a gain to an output signal of said processing mechanism to produce a resulting signal, wherein the gain is adjusted based only on the input signal input to the processing circuitry.   
   
   
       8 . The system of  claim 7 , wherein the desired signal and the undesired signal have approximately equal orders of magnitude. 
   
   
       9 . The system of  claim 7 , wherein the processing circuitry is configured to attenuate the undesired signal, the attenuating not substantially affecting the desired signal. 
   
   
       10 . The system of  claim 7 , wherein the desired signal is not present in the unprocessed input signal, wherein the AGC is configured to increase the gain applied to the output signal of the processing mechanism. 
   
   
       11 . The system of  claim 7 , wherein the desired signal represents a voice signal and wherein the undesired signal represents an echo of a tone. 
   
   
       12 . The system of  claim 11 , wherein the input signal is generated by a recording device. 
   
   
       13 . The system of  claim 7 , wherein said filter comprises a notched filter. 
   
   
       14 . An apparatus comprising:
 a first input configured to receive a processed signal from a processing circuitry, said processed signal comprising at least one an attenuated undesirable signal and a desired signal;   a second input configured to receive an input signal, said input signal comprising at least one of said desired signal and said undesired signal prior to attenuation; and   an amplifier configured to adjustably apply a gain to said processed signal received at said first input to produce a resulting signal, wherein the gain is adjusted based only on said input signal received at said second input.   
   
   
       15 . An article comprising a storage medium having stored thereon instructions that when executed by a machine result in the following:
 attenuating an undesired signal in an input signal to produce a processed signal, said input signal comprising at least one of a desired signal and said undesired signal; and   adjustably applying a gain to the processed signal to produce a resulting signal, wherein the gain is adjusted based only on the input signal prior to attenuation.   
   
   
       16 . The article of  claim 15 , wherein the desired signal and the undesired signal have approximately equal orders of magnitude. 
   
   
       17 . The article of  claim 15 , wherein the desired signal is not present in the input signal, wherein the adjustably applying the gain includes increasing the gain applied to the processed signal. 
   
   
       18 . The article of  claim 15 , wherein the desired signal represents a voice signal and wherein the undesired signal represents an echo of a tone. 
   
   
       19 . The article of  claim 18 , wherein the resulting signal is received by dictation software.