User's Manual

20 ALFOplus 24GHz (North America) - Release 01.05.0x - MN.00395.E - 004
6 TECHNICAL SPECIFICATION
For more details, refer to Section 8. RF CHARACTERISTICS.
6.1 ADAPTIVE MODULATION
ALFOplus ODU’s implement an adaptive modulation algorithm to improve the system gain when the quality
of the received signal become insufficient to guarantee an error free link.
Adaptive modulation guarantees error free and hitless unidirectional downshifts with fading speed up to 30
dB/s. Ethernet frames aren’t lost in case of upshift and downshift events.
The thresholds for ACM are shown in the Tab.2
.
Tab.2 - ACM switching thresholds
7MHz Bandwidth
Power
(Estim.)
BER 10
-6
(Estim.)
Down-shift
(Estim.)
Margin
(Estim.)
Up-shift
a
(Estim.)
Margin
(Estim.)
Up-shift
b
(Estim.)
Margin
(Estim.)
4SQAM 0 6.4 13.2 13.2
4QAM 0 8.2 11.2 3 17.7 5 20.2 5.0
16SQAM -2.5 12.7 15.7 3 19.6 5 19.6 7.5
16QAM -2.5 14.6 17.6 3 22.2 5 23.5 5.0
32QAM -3.75 17.2 20.2 3 24.7 5 24.5 6.3
64QAM -3.5 19.7 22.7 3 27.8 5 27.8 4.8
128QAM -3.5 22.8 25.8 3 31 5 31.6 5.0
256QAM -4.125 26 29 3 34.1 5 34.1 5.6
512QAM -4.25 29.1 32.1 3 36.8 5 36.8 5.1
1KQAM -4.25 32.3 35.3 3 4.5 4.5
10MHz Bandwidth
Power
(Estim.)
BER 10
-6
(Estim.)
Down-shift
(Estim.)
Margin
(Estim.)
Up-shift a.
(Estim.)
Margin
(Estim.)
Up-shift
b.
(Estim.)
Margin
(Estim.)
4SQAM 0 6.4 0 0 13.2 0 13.2 0
4QAM 0 8.2 11.2 3 17.7 5 20.2 5.0
16SQAM -2.5 12.7 15.7 3 19.6 5 19.6 7.5
16QAM -2.5 14.6 17.6 3 22.2 5 23.45 5.0
32QAM -3.75 17.2 20.2 3 24.7 5 24.45 6.25
64QAM -3.5 19.7 22.7 3 27.8 5 27.8 4.75
128QAM -3.5 22.8 25.8 3 31 5 31.625 5.0
256QAM -4.125 26 29 3 34.1 5 34.1 5.625