RS8953 Conexant Systems, Inc., RS8953 Datasheet - Page 82

• Manufacturer Part Number: RS8953
• Description: High-bit-rate Digital Subscriber Line (hdsl) Channel unit
• Manufacturer: Conexant Systems, Inc.

4.0 Registers
4.2 HDSL Transmit
REPEAT_EN
EXT_ZBIT
STUF_CNTR_MODE
4-14
Enable Repeater Mode—When set in both CH1 and CH2, REPEAT_EN cross-connects HDSL
payload, SYNC, STUFF, and Z-bits from receive to transmit to implement a single pair
repeater. REPEAT_EN has no effect in CH3. Transmit 6 ms frames are forced to align to
cross-connected receive 6 ms frames. HOH bits (EOC, IND, and CRC) are inserted by each
channel’s transmit HOH multiplexer to allow for translation of repeater specific IND bits.
HDSL bit clocks, BCLK1, and BCLK2 can operate with separate phase, but must be identical
in long-term frequency. Receive payload from CH1 and CH2 can still be mapped and PCM
combined, but transmit PCM inputs are ignored.
Enable External Z-bits—Is set in conjunction with TAUX_EN when the system supplies the
last 40 Z-bits for transmission from TAUXn input.
Selects the operation of the counter that measures the phase difference between the PCM and
HDSL line clocks. If this bit is cleared in any of the registers for the three channels, the
stuffing generator is in a mode ion which the counter is not allowed to wrap around. In this
mode, the stuffing algorithm is based on only current conditions.
mode in which the counter is allowed to wrap around. In this mode, the stuffing algorithm is
based on both previous decisions and current conditions. This changes the stuffing pattern,
which causes reduced low frequency wander and increased high frequency jitter.
When this bit is set in each of the registers for the 3 channels, the stuffing generator is in a
0 = Normal transmit
1 = Cross-connect CH1 and CH2
0 = Last 40 Z-bits supplied by TZBIT2–TZBIT6 registers
1 = Last 40 Z-bits supplied by TAUXn
0 = Increased wander and decreased jitter (in any register)
1 = Decreased wander and increased jitter (in all three registers)
Conexant
RS8953B/8953SPB
HDSL Channel Unit
N8953BDSB