
XRT84L38
237
REV. 1.0.1
OCTAL T1/E1/J1 FRAMER
data of Channel 0-3 are multiplexed onto the Receive Serial Data pin of Channel 0. Payload and signaling data
of Channel 4-7 are multiplexed onto the Receive Serial Data pin of Channel 4.
Free-running clocks of 16.384MHz are supplied to the Receive Serial Clock pin of Channel 0 and Channel 4 of
the framer. The Receive High-speed Back-plane Interface of the farmer provides data at rising edge of this
Receive Serial Clock. The local Terminal Equipment then latches incoming serial data at falling edge of the
clock.
The Receive High-speed Back-plane Interface maps four 1.544Mbit/s DS1 data streams into this 16.384Mbit/s
data stream as described below:
1.
The F-bit of four channels are repeated and grouped together to form the first octet of the multiplexed data
stream. The F-bit of Channel 0 is sent first, followed by F-bit of Channel 1 and 2. The F-bit of Channel 3 is
sent last. The table below shows bit-pattern of the first octet.
F
X
: F-bit of Channel X
2.
After the first octet of data is sent, the Receive High-speed Back-plane Interface should insert seven octets
(fifty-six bits) of "don't care" data into the outgoing data stream.
3.
Payload data of four channels are repeated and grouped together in a bit-interleaved way. The first pay-
load bit of Timeslot 0 of Channel 0 is sent first, followed by the first payload bit of Timeslot 0 of Channel 1
and 2. The first payload bit of Timeslot 0 of Channel 3 is sent last. After the first bits of Timeslot 0 of all four
channels are sent, it comes the second bit of Timeslot 0 of Channel 0 and so on. The table below demon-
strates how payload bits of four channels are mapped into the 16.384Mbit/s data stream.
XY: The Xth payload bit of Channel Y
4.
The Receive High-speed Back-plane Interface also multiplexed signaling bits with payload bits and sent
them together through the 16.384Mbit/s data stream. When the Receive High-speed Back-plane Interface
is sending the fifth payload bit of a particular channel, instead of sending it twice, it inserts the signaling bit
A of that particular channel. Similarly, the sixth payload bit of a particular channels is followed by the signal-
ing bit B of that channel; the seventh payload bit is followed by the signaling bit C; the eighth payload bit is
followed by the signaling bit D.
FIRST OCTET OF 16.384MBIT/S DATA STREAM
B
IT
0
B
IT
1
B
IT
2
B
IT
3
B
IT
4
B
IT
5
B
IT
6
B
IT
7
F
0
F
0
F
1
F
1
F
2
F
2
F
3
F
3
NINTH OCTET OF 16.384MBIT/S DATA STREAM
B
IT
0
B
IT
1
B
IT
2
B
IT
3
B
IT
4
B
IT
5
B
IT
6
B
IT
7
1
0
1
0
1
1
1
1
1
2
1
2
1
3
1
3
TENTH OCTET OF 16.384MBIT/S DATA STREAM
B
IT
0
B
IT
1
B
IT
2
B
IT
3
B
IT
4
B
IT
5
B
IT
6
B
IT
7
2
0
2
0
2
1
2
1
2
2
2
2
2
3
2
3