Pcm-31C; T1-D4/T1-D4-S; T1-Esf/T1-Esf-S; Multidestinational Systems - Radyne DMD20 Installation And Operation Manual

DMD20/DMD20 LBST Universal Satellite Modem Theory of Operation
3.11.3 PCM-31
The PCM-31 Mode of Operation supports an E1 Interface with no Multiframe Alignment (MFAS)
or Channel Associated Signaling (CAS). The user may independently program n timeslots to
drop and n timeslots to insert where n = 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, or 30. Because
there is no implied ABCD signaling, the user is free to select timeslot 16 as a Drop or Insert
Timeslot.

3.11.4 PCM-31C

The PCM-31C Mode of Operation supports an E1 Interface with no Multiframe Alignment (MFAS)
or Channel Associated Signaling (CAS). In addition, the Drop Function verifies the received
terrestrial CRC checksum and the Insert Function calculates the required CRC checksum. The
user may independently program 'n' timeslots to drop and 'n' timeslots to insert where 'n' = 1, 2,
3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, or 30. Because there is no implied ABCD signaling, the user
is free to select timeslot 16 as a Drop or Insert Timeslot.

3.11.5 T1-D4/T1-D4-S

The T1-D4 Mode of Operation supports a T1 Interface with 12 frames per multiframe. The user
may independently program n timeslots to drop and n timeslots to insert where n = 1, 2, 3, 4, 5, 6,
8, 10, 12, 15, 16, 20, 24, or 30. In the DMD20, Robbed Bit Signaling (RBS) is handled without
any need for operator intervention and is transparent to the user.

3.11.6 T1-ESF/T1-ESF-S

The T1-ESF Mode of Operation supports a T1 Interface with 24 frames per multiframe. The
CRC-6 checksum is automatically checked by the Drop Function and generated by the Insert
Function and placed in the appropriate F-bit positions in the terrestrial multiframe. The user may
independently program n timeslots to drop, and n timeslots to insert, where n = 1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16, 20, 24, or 30. In the DMD20, Robbed Bit Signaling (RBS) is handled without any
need for operator intervention and is transparent to the user.

3.12 Multidestinational Systems

Because the Drop and Insert Functions are completely independent, the DMD20 easily supports
multidestinational communications. Figure 3-15 illustrates a Multidestinational System with one
Hub site and three remote sites. At the Hub site, thirty channels are being transmitted to all three
remote sites and a fractional set of channels is being received from each remote site. At the
other end of the link, each remote site is transmitting a fractional E1 to the Hub site as well as
receiving all 30 channels from the Hub site. It also identifies those channels intended for it, and
inserts them into the terrestrial data stream.
TM103 – Rev. 2.5 3-17