
XRT84L38
323
REV. 1.0.1
OCTAL T1/E1/J1 FRAMER
9.5.2
Configure the framer to transmit Robbed-bit Signaling
The XRT84L38 framer supports transmission of Robbed-bit Signaling in ESF, SF and SLC96 framing
formats. Signaling bits can be inserted into the outgoing DS1 frame through the following:
Signaling data is inserted from Transmit Signaling Control Registers (TSCR) of each timeslot
Signaling data is inserted from TxSig_n pin
Signaling data is embedded into the input PCM data coming from the Terminal Equipment
9.5.2.1
Insert Signaling Bits from TSCR Register
The four most significant bits of the Transmit Signaling Control Register (TSCR) of each timeslot can be used
to store outgoing signaling data. The user can program these bits through microprocessor access. If the
XRT84L38 framer is configure to insert signaling bits from TSCR registers, the DS1 Transmit Framer block will
strip off the least significant bits of signaling frames and replace it with the signaling bit stored inside the TSCR
registers. The insertion of signaling bit into PCM data is done on a per-channel basis. The most significant bit
(Bit 7) of TSCR register is used to store Signaling bit A. Bit 6 is used to hold Signaling bit B. Bit 5 is used to
hold Signaling bit C. Bit 4 is used to hold Signaling bit D.
In SF or SLCa96 mode, the user can control the XRT84L38 framer to transmit no signaling (transparent), two-
code signaling, or four-code signaling. Two-code signaling is done by substituting the least significant bit (LSB)
of the specific channel in frame 6 and 12 with the content of the Signaling bit A of the specific TSCR register.
N
OTE
:
The user should make sure that Signaling bit A and Signaling bit B of the specific TSCR register have the same
value.
Four-code signaling is done by substituting the LSB of channel data in frame 6 with the Signaling bit A and the
LSB of channel data in frame 12 with the Signaling bit B of the specific channel's TSCR register. If sixteen-code
signaling is selected in SF format, only the Signaling bit A and Signaling bit B information are used.
In ESF mode, the user can control the XRT84L38 framer to transmit no signaling (transparent) by disable
signaling insertion, two-code signaling, four-code signaling or sixteen code signaling. Two-code signaling is
done by substituting the least significant bit (LSB) of the specific channel in frame 6, 12, 18 and 24 with the
content of the Signaling bit A of the specific TSCR register.
N
OTE
:
The user should duplicate the contents of Signaling bit A of the specific TSCR register to Signaling bit B, C and D.
Four-code signaling is done by substituting the LSB of channel data in frame 6 and frame 18 with the Signaling
bit A and the LSB of channel data in frame 12 and frame 24 with the Signaling bit B of the specific channel's
TSCR register.
N
OTE
:
The user should duplicate the contents of Signaling bit A of the specific TSCR register to Signaling bit C and
duplicate the contents of Signaling bit B of the specific TSCR register to Signaling bit D.
Sixteen-code signaling is implemented by substituting the LSB of channel data in frames 6, 12, 18, and 24 with
the content of Signaling bit A, B, C, and D of TSCR register respectively.
In N mode, no robbed-bit signaling is allowed and the transmit data stream remains intact.
18
C
24
D
F
RAME
N
UMBER
S
IGNALING
B
IT