4RF Aprisa SR+ User Manual - page 111
Managing the Radio | 109
Aprisa SR+ User Manual 1.5.3
ADAPTIVE CODING MODULATION
These settings are only used if the Modulation Type is set to Adaptive and only apply to the remote to
base / base-repeater / repeater direction of transmission (upstream).
Default Modulation
This parameter sets the default modulation and FEC code rate for the remote to base / base-repeater /
repeater direction of transmission when the ACM mechanism fails for whatever reason. It is also used
when the radio starts up, and subsequently, if there are no recommendations received from the base /
base-repeater / repeater station, it will remain at that setting.
Upstream recommendations are always expected to be received from the base / base-repeater / repeater
station. For example, when the base / base-repeater / repeater station 'ACM control' is set to 'disabled'
and the 'modulation type' at the remote is set to 'adaptive', the default modulation will be used. In this
case, the base / base-repeater / repeater station will not recommend any changes to the remote radios
and so the remote radio will remain on the configured ‘Default Modulation’.
This parameter sets the TX Modulation Type for the remote station radio.
Option
Function
QPSK (High Gain)
Sets the modulation to QPSK with Max Coded FEC.
QPSK (Low Gain)
Sets the modulation to QPSK with Min Coded FEC.
QPSK
Sets the modulation to QPSK with no FEC.
16QAM (High Gain)
Sets the modulation to 16 QAM with Max Coded FEC.
16QAM (Low Gain)
Sets the modulation to 16 QAM with Min Coded FEC.
16QAM
Sets the modulation to 16 QAM with no FEC.
64QAM (High Gain)
Sets the modulation to 64 QAM with Max Coded FEC.
64QAM (Low Gain)
Sets the modulation to 64 QAM with Min Coded FEC.
Modulation Range
This parameter sets the upper limit that the Adaptive Code Modulation can automatically adjust up to.
The lower limit is fixed to QPSK (High Gain).