28 | About the Radio
Aprisa SRi User Manual 1.1.0
Adaptive Coding and Modulation
The Aprisa SRi provides Adaptive Coding and Modulation (ACM) which maximizes the use of the RF path to
provide the highest radio capacity available.
ACM automatically adjusts the modulation coding and FEC code rate in the remote to base direction of
transmission over the defined modulation range based on the signal quality for each individual remote radio.
When the RF path is healthy (no fading), modulation coding is increased and the FEC code rate is decreased
to maximize the data capacity.
If the RF path quality degrades, modulation coding is decreased and the FEC code rate is increased for
maximum robustness to maintain path connectivity.
System Gain vs Modulation
This table defines the modulation order based on gross capacity:
Modulation
Capacity
QPSK (Low Gain)
Minimum
16QAM (Low Gain)
64QAM (Low Gain)
Maximum
This table defines the modulation order based on receiver sensitivity:
Modulation
Coverage
QPSK (Low Gain)
Maximum
16QAM (Low Gain)
64QAM (Low Gain)
Minimum