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Method for Reducing the Effects of Noise and Low Level Signals on Automatic Gain Control Amplifiers

IP.com Disclosure Number: IPCOM000060332D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Einkauf, MA: AUTHOR

Abstract

A method is described which allows signal processing algorithms containing an AGC (Automatic Gain Control) to process only signals whose magnitudes are above a specified threshold of the AGC amplifier. An AGC is used to amplify all input signals so that the output of the AGC is of uniform magnitude, independent of the input signal's magnitude. One problem with this traditional AGC is that there is no way to set a limit on the minimum magnitude the signal must be to be processed by the AGC. For example, if a system is specified to process only signals above 100 millivolts rms or more, there is no way to restrict signals below 100 mv from being processed by the AGC with software. One way to limit the minimum magnitude the AGC will process is to limit the maximum gain the AGC is capable of.

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Method for Reducing the Effects of Noise and Low Level Signals on Automatic Gain Control Amplifiers

A method is described which allows signal processing algorithms containing an AGC (Automatic Gain Control) to process only signals whose magnitudes are above a specified threshold of the AGC amplifier. An AGC is used to amplify all input signals so that the output of the AGC is of uniform magnitude, independent of the input signal's magnitude. One problem with this traditional AGC is that there is no way to set a limit on the minimum magnitude the signal must be to be processed by the AGC. For example, if a system is specified to process only signals above 100 millivolts rms or more, there is no way to restrict signals below 100 mv from being processed by the AGC with software. One way to limit the minimum magnitude the AGC will process is to limit the maximum gain the AGC is capable of. However, this still allows signals below the specified minimum magnitude to be amplified by the AGC and then processed by all components following the AGC, although the resulting output will be less than the output for input signals above the minimum requirements. One way to avoid this is to set the output of the AGC to zero if the input is below the minimum magnitude. An advantage of this method is that the resulting output levels of filters following the AGC will be approximately zero. This allows decisions which are determined by output filter levels to be less ambiguous, since...