11-2
Chapter 11
Adding Interface Cards to the System
How to Calculate the Number of MFM and SCM Daughterboards Required
Each interface card installed in the system has its own “MFMU” value (see table, below). These
values are used to calculate the number of daughterboards required.
There is a maximum of three SCM and MFM daughterboards in any system (one SCM and two
MFMs). Note also that an SCM board is essential if more than six Conference channels are re-
quired.
Each cabinet (shelf) already contains four DSPs.
Card MFMU Values
TRK B 8TRK PRI TEPRI 8BSI AC15 DLI 16DLI SLI
4 8 0 0 0 3 0 0 0
8SLI 16SLI BRI 8MWSLI 16MWSLI AA SVMi-8 / 16
Cadence
MGI
8 16 0 8 16 0 0 0
To calculate your requirement:
1. Add together the MFMU values of all cards in the system to obtain the “rate” as shown in the
following table.
Total MFMU Value Rate
Up to 20 3
20–40 4
More than 40 5
2. Use the following calculation to obtain a number between 0 and 3:
((Total MFMUs / Rate – (No. of shelves x 4)) / 12
Round up the result if necessary to obtain your number. This number then defines the number of
SCM and MFM boards required according to the following table:
Number Calculated SCMs Required MFMs Required
0 0 0
1 1 0
2 1 1
3 1 2
(Note: the number of SCMs will be forced to ‘1’ if more than six Conference channels are needed.)
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