Specifications
DMD20/20LBST Universal Satellite Modem Drop and Insert (D&I)
MN-DMD20-20LBST Revision 14 H–14
Table H-2. D&I ROM Maps
ROM Map
T1/E1 Time Slot
# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
3 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2
4 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6
5 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6
6 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6
7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Since the D&I Functions are separate and distinct, two separate maps must be configured at the
start of the D&I Multiplexer Operation. These are the Tx (transmit) Active Map for Drop Mapping
and the Rx (receive) Active Map for Insert Mapping. The number of entries in each map is
determined by the data rates selected. Each map entry consists of an IBS Time Slot assignment
and the Terrestrial (T1 or E1) Channel Number to which it is assigned. Drop Mapping and Insert
Mapping are completely separate and independent.
The map that is actually used for the Drop Function is the Tx Active Map; the map that is actually
used for the Insert function is the Rx Active Map. Two additional maps exist: the Tx Edit Map and
the Rx Edit Map. The Edit Maps are the buffer areas that are used when creating or modifying a
map through the modem’s LCD; when editing is complete, the appropriate map should be copied
to the Active Map.
Any map may be copied to any other map with the exception of the ROM maps. These maps
may only be the source of the data used to create a User, Edit, or Active Map.
Maps can be created in the map editor and stored as “User Maps”. New “Active Maps” can be
downloaded during Modem Operation but this will result in a temporary disruption of service on
the terrestrial line or the Satellite transmission.
The following paragraphs give examples of typical configurations that could use the ROM Maps
as templates. The ROM Map used would have to be first copied to the appropriate Active
Transmit (Drop) and/or Active Receive (Insert) Map(s) before it could be used. To use a
modification of a ROM Map, the ROM Map must first be copied to the appropriate Edit Map, then
modified, and then copied to the appropriate Active Map.
The mapping of channels to time slots is arbitrary; it is not necessary to map CH1 to
TS1, CH2 to TS2, etc. The channel to the time slot mapping may be in any order
within the constraints of the number of available channels.
For example, ROM Map 1 could be used as the template for an Active Transmit (Drop) Map
within a modulator configured for 64 Kbps operation. Only the first time slot of the T1 or E1 frame
would be dropped into the modulator transmit path. The Drop Multiplexer would know to look
only at the first entry in the Active Transmit table and would ignore the other 29 entries. If the
map contained an “8” in its first entry, the eighth channel of the T1/E1 frame would be sent to the
modulator.
IMPORTANT