An Automatic Gain Control system ca

An Automatic Gain Control system can be enabled by setting the relevant bits of the Program register P4.9. The setting of the Input 1 Gain stage is recorded when the device enters Tx mode and if the signal exceeds the pre-set threshold, the Input 1 Gain is automatically reduced in 3.2dB steps until it falls within the operational levels or the range of the gain stage is exhausted. When the signal level drops, the gain will be automatically increased in 3.2dB steps at the rate set in P4.9 until the initial value has been reached. For maximum effect the system should be designed such that the +22.4dB setting of the Input 1 Gain stage achieves the nominal levels. To ensure consistent operation, it is recommended that the Input 1 Gain stage value be re-initialised before entering Tx mode. The signal that is used as an input to this process can be selected to be either:o Output of Input1 gain stageo Output of the Pre-emphasis filter.by selecting the relevant bit in P4.9. The Pre-emphasis option should only be chosen if this block is actually in use.