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. 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;
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; and
if the total power level of the multi-channel signal output from the VGA is below the low power threshold for the ADC, 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.
2. The AGC according to claim 1 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.
3. The AGC according to claim 2 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.
4. The AGC according to claim 1 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.
5. A system incorporating the AGC according to claim 1 , 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.
6. The system according to claim 5 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.
7. 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;
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; and
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.
8. The method according to claim 7 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.
9. The method according to claim 8 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.
10. The method according to claim 7 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.
11. The method according to claim 7 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.
12. The method according to claim 11 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.
13. 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; 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; and 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.
14. The multi-channel receiver according to claim 13 , 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.
15. The multi-channel receiver according to claim 14 , 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.
16. The multi-channel receiver according to claim 13 , 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.
17. The multi-channel receiver according to claim 13 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.
18. 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 fixed nominal analog gain to an incoming multi-channel signal in a first state prior to receipt of a signal to ensure a total power level of the multi-channel signal output from the VGA is at a desired acquisition level for the ADC; and
upon receipt of a signal, apply a second fixed nominal analog gain to all incoming multi-channel signals in a second state 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.
19. The AGC according to claim 18 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 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 level for the ADC.
20. A system incorporating the AGC according to claim 18 , 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.
21. 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 fixed nominal analog gain to an incoming multi-channel signal in a first state prior to receipt of a signal to ensure a total power level of the multi-channel signal output from the gain amplifier is at a desired acquisition level for digitizing; and
upon receipt of a signal, applying a second fixed nominal analog gain to all incoming multi-channel signals in a second state 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.
22. The method according to claim 21 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 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.
23. The method according to claim 21 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.
24. 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 fixed nominal analog gain to an incoming multi-channel signal in a fixed state prior to receipt of a signal to ensure a total power level of the multi-channel signal output from the VGA is at a desired acquisition level for the ADC; and upon receipt of a signal, apply 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 a high power threshold for the ADC or below a low power threshold for the ADC.
25. The multi-channel receiver according to claim 24 , 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 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 level for the ADC.