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PRELIMINARY
XRT86VL38
REV. P1.0.6
OCTAL T1/E1/J1 FRAMER/LIU COMBO
314
4.9
Robbed Bit Signaling/CAS Signaling
Signaling is used to convey status information relative to the individual DS-0’s. If a particular DS-0 is On Hook,
Off Hook, etc. this information is carried within the robbed bits in T1 (SF/ESF/SLC-96) or the sixteenth time slot
in E1. On the transmit path, the Signaling information can be inserted through the PCM data, internal registers,
or a dedicated external Signaling Bus by programming the appropriate registers. On the receive path, the
signaling information is extracted (if enabled) to the internal registers and the external signaling bus in addition
to being embedded within the PCM data. If the user wishes to substitute the ABCD values, the substitution
only occurs in the PCM data. Once substituted, the internal registers and the external signaling bus will not be
affected. Figure 21 is a simplified block diagram showing the Signaling Interface. Figure 22 is a timing
diagram showing how to insert the ABCD values for each time slot in ESF / CAS. Figure 23 is a timing diagram
showing how to insert the AB values for SF / SLC-96 or 4-code signaling in ESF / CAS.
F
IGURE
21. R
OBBED
B
IT
S
IGNALING
/ CAS S
IGNALING
F
IGURE
22. ESF / CAS E
XTERNAL
S
IGNALING
B
US
RBS/CAS
Signaling
Substitution
PCM Data
Tx LIU
TSCR
Internal Reg's
Rx LIU
Signaling
Extraction
PCM Data
RSAR
Internal Reg's
Transmit Direction
Receive Direction
TxSER
TxCHN0/
TxSIG
RxSER
RxCHN0/
RxSIG
Physical
Interface
TxSYNC
TxMSYNC
TxSERclk
TxCHN0/TxSIG
TxSER
F
D
C
B
A
TS 1
D
C
B
A
D
C
B
A
TS 2
TS 3