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OM20 Universal Outdoor Modem
E.7
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
Map Locations
(Kbps)
Used (n = 1,
2,4,8,16,24,30)
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:
At 384 Kbps, 384/64 = 6 entries.
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.
ROM maps are read-only and may not be modified (refer to Table E-2).
TM116 – Rev. 1.2
1
1-2
1-4
1-6
1-8
1-12
1-16
1-24
1-30
Appendix E
E-
12
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