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Chapter 4 - Operation and Administration
BreezeACCESS VL System Manual
186
NOTE
The SNR measurement at the AU is accurate only when receiving transmissions from the
applicable SU. If necessary, use the Ping Test utility in the Site Survey menu to verify data
transmission.
When the Adaptive Modulation Algorithm is disabled, this parameter will serve to
determine Fixed Modulation Level used for transmissions.
The minimum and maximum values for the Maximum Modulation Level are
defined by the Sub-Band in use. For information on how to view the Sub-Bands
supported by the unit and the supported parameters’ values and options, refer to
section 4.2.2.4
. Currently, all Sub Bands support the entire range of modulation
levels, from 1 to 8. However, the highest modulation level supported by units with
HW revision A is modulation level 7.
VL 900 SUs with HW revision F use a default maximum modulation level of 5. For
the rest of the units, the default is the highest supported modulation level (8 for
all units with HW revision B or higher, 7 for units with HW revision A).
Table 4-12: Recommended Maximum Modulation Level*
SNR Maximum Modulation Level
SNR > 23 dB 8
21 dB < SNR < 23 dB 7
16 dB < SNR < 21 dB 6
13 dB < SNR < 16 dB 5
10 dB < SNR < 13 dB 4
8 dB < SNR < 10 dB 3
7 dB < SNR < 8 dB 2
6 dB < SNR < 7 dB 1
* The maximum supported value depends on the unit’s HW revision and on the Max Modulation
Level according to the Sub-Band.
4.2.6.5.5 Average SNR Memory Factor
The Average SNR Memory Factor defines the weight of history (value of last
calculated average SNR) in the formula used for calculating the current average
SNR for received data frames. This average SNR is used by the ATPC algorithm in
the AU and is also included in the Adaptive Modulation Algorithm information
messages transmitted by the AU and the SU. The higher the value of this
parameter, the higher is the weight of history in the formula.