WiNRADiO G65DDC User’s Guide
58
AGC
The
Automatic Gain Control
(
AGC
) acts upon the digitally down-converted
and filtered demodulator passband, in order to keep the signal coming to the
demodulator at a constant level.
This is in fact functionally similar to AGC typically implemented in conventional
receivers, which also works on the IF signal prior to demodulation. The
difference is that in a conventional receiver, this is implemented in hardware,
while with the Excalibur Sigma it is a software function.
The AGC has six speed settings:
Slow
,
Medium
,
Fast
,
User 1
,
User 2
and
User 3
. These make it possible to select the speed with which the AGC reacts.
Typically, the AGC would be in the medium position.
For most practical applications, the medium setting is recommended. Slow
setting would be used especially with Morse code (CW mode), while fast AGC
speed might be appropriate for very noisy signals, where noise bursts might
temporarily desensitize the receiver if a slower AGC was employed.
While the timing of the slow, medium or fast speed settings is fixed, the
remaining three settings are user-definable, making it possible to specify the
Attack
and
Decay
times:
The attack time is the speed with which the AGC reacts to a rising signal level,
while the decay time is the speed with which it reacts to a falling signal level.
These settings are recommended only for advanced users.
When enabled, the AGC tries to maintain the audio output at a constant level,
referred to as the
AGC reference level
. This level is also user adjustable
under the gain tab, using the
Ref. level
control:
