BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 39

• Manufacturer Part Number: BT8954
• Description: VOICE PAIR GAIN FRAMER
• Manufacturer: CONEXANT [Conexant Systems, Inc]

Bt8954
Voice Pair Gain Framer
Figure 3-15. COTF and RTF Synchronization
3.7.1 COTF Transmitter Synchronization
Figure 3-16. COTF Transmitter Synchronization
N8954DSC
TPCM_6 ms
RPCM_6 ms
TDSL_6 ms
TPCM_6 ms
(Master)
(Slave)
RPCM_6 ms!= TPCM_6 ms
COT Framer
Transmitter.COT
Receiver.COT
TFIFO_WL.COT
3.7 Synchronization
All signals are synchronized to TDSL_6ms, RDSL_6ms, TPCM_6ms, and
RPCM_6ms. All status registers are synchronized to either TDSL_6ms or
RDSL_6ms. The transmitter signals at the DSL (PCM) interface are synchronized
to TDSL_6ms (TPCM_6ms). The receiver signals at the DSL (PCM) interface are
synchronized to RDSL_6ms (RPCM_6ms). The main contributor to the phase
differences between the DSL_6ms and PCM_6ms signals is that while data is
received and transmitted in a bursty fashion at the PCM interface, it is received
and transmitted in a continuous fashion at the DSL interface.
depends on whether the framer is at the Central Office (COTF) or at the Remote
Site (RTF). Even though TPCM_6ms and RPCM_6ms may not be phase-aligned,
TFIFO and RFIFO provide sufficient data buffering for PCMF to mark coincident
PCM receive and transmit 125 s frame boundaries. The synchronization
between COTF and RTF is illustrated in
In the COTF, TPCM_6 ms is always a free-running 6 ms-period signal. At the
Central Office, the DSL transmit frames are slaved to the PCM frame timing. As
illustrated in
from TPCM_6ms by TFIFO_WL.COT (TFIFO Water Level in the COTF).
TFIFO_WL.COT determines the amount of PCM data written into the TFIFO
before the transmitter begins extracting DSL frames from the TFIFO.
The detailed relationship between the DSL_6ms and PCM_6ms signals
TDSL_6 ms
(Slave)
RDSL_6 ms
(Master)
Figure
Conexant
3-16, TDSL_6 ms is a 6 ms-period signal that is phase-offset
Variable
6 ms
Delay
Path
6 ms
TDSL_6 ms
RDSL_6 ms
(Master)
(Slave)
Figure
RPCM_6 ms = TPCM_6 ms
3-15.
Transmitter.RT
Receiver.RT
RT Framer
3.0 Circuit Descriptions
3.7 Synchronization
TPCM_6 ms
(Master)
RPCM_6 ms
(Slave)
3-17