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DMD50 Universal Satellite Modem
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.
IMPORTANT
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.
ROM Map 2 could be used as the template for an Active Receive (Insert) Map within a
demodulator configured for 128 Kbps operation. The demodulated data in the receive path would
be inserted into the first two time slots of the T1 or E1 frame. The Insert Multiplexer would know
to look only at the first two entries in the Active Receive table and would ignore the other 28
entries. If the first two entries were modified to contain a 27 and 28, the data would be inserted
th
into the 27
and 28
ROM Map 3 could be used as the template for an Active Transmit (Drop) Map with a modulator
and/or demodulator configured for 256 Kbps operation. The T1 or E1 Data in the transmit path or
the demodulated data in the receive path would be dropped from and/or inserted into the first four
time slots of the T1 or E1 frame. The Multiplexer would know to look only at the first 4 entries in
the Active map(s) and would ignore the other 26 entries.
ROM Map 4 could be used as the template for an Active Transmit (Drop) or Active Receive
(Insert) Map with a modulator and/or demodulator configured for 384 Kbps operation. The T1 or
E1 Data in the transmit path or the demodulated data in the receive path would be dropped from
and/or inserted into the first six time slots of the T1 or E1 frame. The Insert Multiplexer would
know to look only at the first six entries in the Active map(s) and would ignore the other 24
entries. To Drop the last six channels of a T1 frame into a modulator transmit path, the first six
entries of the Active Transmit map should contain 19, 20, 21, 22, 23, and 24.
ROM Map 5 could be used as the template for an Active Transmit (Drop) and/or Active Receive
(Insert) Map with a modulator and/or demodulator configured for 512 Kbps operation. The T1 or
E1 Data in the transmit path or the demodulated data in the receive path would be dropped from
and or inserted into the first eight time slots of the T1 or E1 frame. The Multiplexer would know
to look only at the first eight entries in the Active map(s) and would ignore the other 22 entries.
To insert data received from a demodulator into channels 17 through 24 of an E1 frame, the first
eight entries of the Active Receive map should contain 17, 18, 19, 20, 21, 22, 23, and 24.
ROM Map 6 could be used as the template for an Active Transmit (Drop) and/or Active Receive
(Insert) Map with a modulator and/or demodulator configured for 768 Kbps operation. The T1 or
E1 Data in the transmit path or the demodulated data in the receive path would be dropped from
and or inserted into the first 12 time slots of the T1 or E1 frame. The Multiplexer would know to
look only at the first 12 entries in the Active map(s) and would ignore the other 18 entries. To
insert data received from a demodulator into channels 3 through 14 of an E1 frame, the first 12
entries of the Active Receive map should contain 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14.
ROM Map 7 could be used as the template for an Active Transmit (Drop) and/or Active Receive
(Insert) Map with a modulator and/or demodulator configured for 1920 Kbps operation. This
would be used with E1 frames where time slot 16 is not used for the multiframe alignment signal
and therefore channels 1 through 30 are mapped directly with time slots 1 through 30.
MN-DMD50 Revision 4
th
time slots of the E1 frame.
Drop and Insert (D&I)
H–15
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