Comtech EF Data OM20 - Manual (Page 194)

OM20 Universal Outdoor Modem Appendix E
MN-OM20– Revision 5 E–12
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)
Map Locations
Used (n = 1,
2,4,8,16,24,30)
64 1
128 1-2
256 1-4
384 1-6
512 1-8
768 1-12
1024 1-16
1536 1-24
1920 1-30
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.