Automatic Gain Control (AGC) For Multichannel/Wideband Communications System
Automatic Gain Control (AGC) system for multi-channel signals attenuates an incoming multi-channel signal by providing a gain. The system further adjusts each individual channel, of the multi-channel signal, by supplying a second gain if needed. The AGC system is designed to ensure a received signal power is at an optimal level for analog to digital conversion or any other form of signal processing. The system also enables elimination of mid-packet gain adjustments.
1 . (canceled)
2 . An automatic gain controller (AGC) to control a variable gain amplifier (VGA) implemented within a multi-channel receiver, the multi-channel receiver comprising the VGA operable to adjust gain of a multi-channel signal, an analog to digital converter (ADC) operable to digitize the output of the VGA and a plurality of digital filters operable to filter the output of the ADC into a plurality of individual channels of different frequencies, the AGC operable to:
apply a first nominal analog gain to an incoming multi-channel signal to ensure a total power level of the multi-channel signal output from the VGA is at a desired acquisition threshold for the ADC; and
apply the first nominal analog gain as a first fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the VGA is above a high power threshold for the ADC or below a low power threshold for the ADC.
3 . The AGC according to claim 2 further operable, if the total power level of the multi-channel signal output from the VGA becomes above the high power threshold for the ADC, to apply a second nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the VGA is at the desired acquisition threshold for the ADC.
4 . The AGC according to claim 3 further operable to subsequently apply the second nominal analog gain as a second fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the VGA is above the high power threshold for the ADC or below the low power threshold for the ADC.
5 . The AGC according to claim 2 further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC, to: determine if a packet is being processed on any of the individual channels, and apply the first nominal analog gain to the multi-channel signal until no packets are being processed on any of the individual channels.
6 . The AGC according to claim 5 further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC and no packet is being processed on any of the individual channels, to apply a third nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the VGA is at the desired acquisition threshold for the ADC.
7 . A system incorporating the AGC according to claim 2 , the system further comprising the VGA controlled by the AGC, the ADC operable to digitize the multi-channel signal output from the VGA, and the plurality of digital filters operable to filter the output of the ADC into the plurality of individual channels of different frequencies.
8 . The system according to claim 7 further comprising a plurality of modems, each of the modems operable to demodulate one of the individual channels; wherein the AGC is further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC, to: determine if a packet is being processed by any of the modems, and apply the first nominal analog gain to the multi-channel signal until no packets are being processed by any of the modems.
9 . A method of controlling a gain amplifier for a multi-channel signal prior to digitizing the multi-channel signal and filtering the digitized multi-channel signal into a plurality of individual channels, the method comprising:
applying a first nominal analog gain to an incoming multi-channel signal to ensure a total power level of the multi-channel signal output from the gain amplifier is at a desired acquisition threshold for digitizing; and
applying the first nominal analog gain as a first fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the gain amplifier is above a high power threshold for digitizing or below a low power threshold for digitizing.
10 . The method according to claim 9 further comprising: if the total power level of the multi-channel signal output from the gain amplifier becomes above the high power threshold for digitizing, applying a second nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the gain amplifier is at the desired acquisition threshold for digitizing.
11 . The method according to claim 10 further comprising: subsequently applying the second nominal analog gain as a second fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the gain amplifier is above the high power threshold for digitizing or below the low power threshold for digitizing.
12 . The method according to claim 9 further comprising: if the total power level of the multi-channel signal output from the gain amplifier is below the low power threshold for digitizing, determining if a packet is being processed on any of the individual channels into which the multi-channel signal is filtered, and applying the first nominal analog gain to the multi-channel signal until no packets are being processed on any of the individual channels.
13 . The method according to claim 12 further comprising: if the total power level of the multi-channel signal output from the gain amplifier is below the low power threshold for digitizing and no packet is being processed on any of the individual channels, applying a third nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the gain amplifier is at the desired acquisition threshold for digitizing.
14 . The method according to claim 9 further comprising digitizing the multi-channel signal output from the gain amplifier and filtering the digitized multi-channel signal into the plurality of individual channels.
15 . The method according to claim 14 further comprising demodulating each of the individual channels with a corresponding modem; wherein the method further comprises: if the total power level of the multi-channel signal output from the gain amplifier is below the low power threshold for the digitizing, determining if a packet is being processed by any of the modems, and applying the first nominal analog gain to the multi-channel signal until no packets are being processed by any of the modems.
16 . A multi-channel receiver comprising:
a variable gain amplifier (VGA) operable to adjust gain of a multi-channel signal;
an analog to digital converter (ADC) operable to digitize the output of the VGA;
a plurality of digital filters operable to filter the output of the ADC into a plurality of individual channels of different frequencies; and
an automatic gain controller (AGC) operable to control the VGA to apply a first nominal analog gain to an incoming multi-channel signal to ensure a total power level of the multi-channel signal output from the VGA is at a desired acquisition threshold for the ADC; and apply the first nominal analog gain as a first fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the VGA is above a high power threshold for the ADC or below a low power threshold for the ADC.
17 . The multi-channel receiver according to claim 16 , wherein the AGC is further operable, if the total power level of the multi-channel signal output from the VGA becomes above the high power threshold for the ADC, to apply a second nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the VGA is at the desired acquisition threshold for the ADC.
18 . The multi-channel receiver according to claim 17 , wherein the AGC is further operable to subsequently apply the second nominal analog gain as a second fixed nominal analog gain to all incoming multi-channel signals unless the total power level of the multi-channel signal output from the VGA is above the high power threshold for the ADC or below the low power threshold for the ADC.
19 . The multi-channel receiver according to claim 16 , wherein the AGC is further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC, to: determine if a packet is being processed on any of the individual channels, and apply the first nominal analog gain to the multi-channel signal until no packets are being processed on any of the individual channels.
20 . The multi-channel receiver according to claim 19 , wherein the AGC is further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC and no packet is being processed on any of the individual channels, to apply a third nominal analog gain to the multi-channel signal to ensure the total power level of the multi-channel signal output from the VGA is at the desired acquisition threshold for the ADC.
21 . The multi-channel receiver according to claim 16 further comprising a plurality of modems, each of the modems operable to demodulate one of the individual channels; and wherein the AGC is further operable, if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC, to: determine if a packet is being processed by any of the modems, and applying the first nominal analog gain to the multi-channel signal until no packets are being processed by any of the modems.