Agc loop design for wireless receiver

i have a misunderstanding for a function of AGC loop in QAM case cuz AGC make a constant signal level for next device and in QAM the information in amplitude, so the different data will be similar.....!
anyone help me please...

Question: Is there a carrier present in this version of QAM (Quadrature Amplitude Modulation)?


Statistically, is is possible to compute an AGC voltage given the average signal strength.

Also, it is possible to use something like a transmitted "training sequence" or 'bit framing sequence' in the series of bits in the transmitted data stream. This can be used to represent a maximum value and then an AGC function derived to adjust this value in the IF.

Jim

The time constant of the AGC is very long (.1 -5 seconds) as it only compensates for change in propagation amplitude, else it would remove the modulation of AM signals. For non carrier modulation such as SSB, the time constant will be even longer -30 secs?
Frank