Comtech EF Data DMD-2050E - Manual (Page 249)

DMD2050E Universal Satellite Modem Efficient Drop and Insert
MN-DMD2050E Revision 2 E–7
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.
E.4.3.4 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.
E.4.3.5 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. Robbed Bit Signaling (RBS) is handled without any need for
operator intervention and is transparent to the user.
E.4.3.6 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. Robbed Bit Signaling (RBS) is handled without any need for
operator intervention and is transparent to the user.
E.4.4 Systems with Multiple Destinations
The independence of the Drop and Insert functions works well in systems with multiple
destinations. Figure E-6 shows a 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.
E.4.5 Drop and Insert Mapping
The following displays under Interface D&I Setup (both Tx and Rx), are editing displays only: