Settings for AGC

[srs4511351]

It has been noted that the software AGC does not sound decoded bandwidth is narrow.
Currently, on SSB, the decay is so short that background noise pumps in and out between the syllables of speech.
The ability so set a longer decay would make this more tolerable, and even desirable.

Some common settings are attack, decay and threshold. Some offer a hang feature that holds the AGC value constant for the specified time.

----Steve