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Hi all,

I am trying to calculate the gain level in Automatic Gain Control. 
Assuming the input is a speech signal at -10 dB power level, if I want 
to change the output of the AGC to be at, say -15 dB, I have to 
multiply the input samples by a scaling constant, which inturn is 
calculated using the Gain level and input frame energy. Frame length = 
10ms(80 samples). Also I am using divide and multiply rule to scale 
the input signal.

How do I determine the gain level for a particular dB output in this 
scenario. Help me out please!!

Thanks
Deepak
	

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Deepak,

Let
   Init db = Intial Gain in db
   Final db = Final Gain in db
   Gain = Required gain to achieve Final db (assuming initital gain was 1.0)
Then
    Gain = 10^[(Final db - Init db )/20]

Regards,
Kral

-----Original Message-----
From: Siddarth [mailto:fri2talk@fri2...] 
Sent: Friday, April 22, 2005 7:29 PM
To: audiodsp@audi...
Subject: [audiodsp] Calculating the Gain Level in AGC
	Hi all,

I am trying to calculate the gain level in Automatic Gain Control. 
Assuming the input is a speech signal at -10 dB power level, if I want to
change the output of the AGC to be at, say -15 dB, I have to multiply the
input samples by a scaling constant, which inturn is calculated using the
Gain level and input frame energy. Frame length = 10ms(80 samples). Also I
am using divide and multiply rule to scale the input signal.

How do I determine the gain level for a particular dB output in this
scenario. Help me out please!!

Thanks
Deepak
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

output=input*gain
 
from the log domain
power=10*log(gain)
finaldB-initdB=10*log(gain)
gain=10^((finaldB-initdB)/10)
substitute this gain to the first equation.
 
Lark, Jon I have to point out that power is 10*log(x) not like energy which is 20*log(x).

"Lark, Jon @ AS" <jon.lark@jon....> wrote:

Deepak,

Let
   Init db = Intial Gain in db
   Final db = Final Gain in db
   Gain = Required gain to achieve Final db (assuming initital gain was 1.0)
Then
    Gain = 10^[(Final db - Init db )/20]

Regards,
Kral

-----Original Message-----
From: Siddarth [mailto:fri2talk@fri2...] 
Sent: Friday, April 22, 2005 7:29 PM
To: audiodsp@audi...
Subject: [audiodsp] Calculating the Gain Level in AGC
	Hi all,

I am trying to calculate the gain level in Automatic Gain Control. 
Assuming the input is a speech signal at -10 dB power level, if I want to
change the output of the AGC to be at, say -15 dB, I have to multiply the
input samples by a scaling constant, which inturn is calculated using the
Gain level and input frame energy. Frame length = 10ms(80 samples). Also I
am using divide and multiply rule to scale the input signal.

How do I determine the gain level for a particular dB output in this
scenario. Help me out please!!

Thanks
Deepak
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(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )