Comtech EF Data RCS10 - Manual (Page 232)

Principles of Operation RCS10 Redundant Communication System
Page 5-16 TM058 - Rev. 2.3
5.10 Mode Selection
The DMD10 Drop & Insert can be easily configured to support several commonly used terrestrial
data formats. For E1 data, the user can choose between PCM-30, PCM-30C, PCM-31 and PCM-
31C. For T1 data, the user can choose between T1-D4, T1-ESF, and SLC-96. The following
paragraphs provide more information on the various mode selection capabilities of the DMD10.
5.10.1 PCM-30
The PCM-30 mode of operation supports an E1 interface with Multiframe Alignment Signaling
(MFAS) and Channel Associated Signaling (CAS). The user may independently program n
timeslots to drop and n timeslots to insert where n = 1, 2, 4, 6, 8, 12, 16, 24, or 30. In addition to
the selected drop timeslots, the transmit function also extracts the appropriate ABCD signaling bits
from terrestrial timeslot 16 for transmission in IBS frame as required. Conversely, the receive
function extracts received ABCD signaling bits from the IBS frame and inserts them in timeslot 16 of
the appropriate terrestrial frame. This transmission and reception of ABCD signaling based upon
the drop and insert timeslots is performed automatically and is transparent to the user. In PCM-30
mode, the user may not select timeslot 16 as a Drop or Insert timeslot.
5.10.2 PCM-30C
The PCM-30C mode of operation supports an E1 interface with Multiframe Alignment (MFAS) and
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, 4, 6, 8, 12, 16,
24, or 30. In addition to the selected Drop timeslots, the transmit function also extracts the
appropriate ABCD signaling bits from terrestrial timeslot 16 for transmission in IBS frame as
required. Conversely, the receive function extracts received ABCD signaling bits from the IBS frame
and inserts them in timeslot 16 of the appropriate terrestrial frame. This transmission and reception
of ABCD signaling based upon the Drop and Insert timeslots is performed automatically and is
transparent to the user. In PCM-30C mode, the user may not select timeslot 16 as a Drop or Insert
timeslot.
5.10.3 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, 4, 6, 8, 12, 16, 24, or 30. Because there is no implied
ABCD signaling, the user is free to select timeslot 16 as a Drop or Insert timeslot.
5.10.4 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, 4, 6, 8, 12,
16, 24, or 30. Because there is no implied ABCD signaling, the user is free to select timeslot 16 as
a Drop or Insert timeslot.
5.10.5 T1-D4
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, 4, 6, 8, 12, 16,
or 24. In the DMD10, Robbed Bit Signaling (RBS) is handled without any need for operator
intervention and is transparent to the user.
5.10.6 T1-ESF