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OM20 Universal Outdoor Modem
E.8
D&I Maps and Map Editing
The Drop and Insert multiplexer is programmed by loading it with a transmit and receive map.
Maps always contain 30 entries, although, only the first "n" entries are relevant (see Table 4-10).
The OM20 includes provisions to copy, change, and store the D&I transmit and receive maps
directly from the Front Panel or via the remote M&C link. These maps are tables that are used to
define and configure the D&I functions. Each map contains up to 30 entries, which are enough
to define the channel assignments for a T1 (24 channel) or E1 (30 channel) frame structure.
Maps that are created are stored in non-volatile memory within the modem and remain
unchanged after a power-down.
Table E-1. D&I Multiplexer Map
Locations Used
Data Rate
(Kbps)
64
128
256
384
512
768
1024
1536
1920
It is important to understand that each map contains up to 30 usable entries. In many cases a
smaller number of entries will be relevant. To determine the number of relevant entries, divide
the data rate by 64 Kbps.
For example:
Therefore, in this case only the first six entries of the map would be relevant.
The Modem is equipped with eight permanently stored default maps, which are designated
ROM 1 through ROM 8. The user may also define, modify, and save an additional eight maps
which are designated USER 1 through USER 8.
MN-OM20– Revision 5
Map Locations
Used (n = 1,
2,4,8,16,24,30)
1
1-2
1-4
1-6
1-8
1-12
1-16
1-24
1-30
At 384 Kbps, 384/64 = 6 entries.
Appendix E
E–12
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