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What's the value of AGC time constant of FM Radio

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OMEsystem

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I would like to design an AGC for FM Radio to avoid the overloading to LNA
by interference. But, I don't know how to select the settling time constant of it.

Would you guys give me some advice to me? Thank you.
 

vfone

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I don’t know if is a spec for this but used values for FM-AGC time constant could be up to 2 seconds, depending by the type of AGC (narrow-band, wide-band, etc).
Compared with AM-AGC where rising and falling time for settling is symmetrical, for FM-AGC usually is asymmetrical (microseconds for rising and milliseconds for falling).
 

OMEsystem

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Thanks for your reply,

1)If the AGC is used to protect LNA, can we call it wide-band AGC?

2)Wide-band AGC or Narrow-band AGC, which one has longer time for settling?

3)Why we need asymmetrical rising and falling time of FM AGC?



Thanks,
 

GDF

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vfone said:
I don’t know if is a spec for this but used values for FM-AGC time constant could be up to 2 seconds, depending by the type of AGC (narrow-band, wide-band, etc).
Compared with AM-AGC where rising and falling time for settling is symmetrical, for FM-AGC usually is asymmetrical (microseconds for rising and milliseconds for falling).

How to implement asymmetrical falling and rising time in AGC system?
 

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