cx29503 Mindspeed Technologies, cx29503 Datasheet - Page 121

• Manufacturer Part Number: cx29503
• Description: Cx29503 Broadband Access Multiplexer Data Sheet
• Manufacturer: Mindspeed Technologies

CX29503 Data Sheet
5.2
Figure 5-2. DS1/E1 Framer Loopbacks
29503-DSH-002-B
DS1 Reference Clock
E1 Reference Clock
SONET Rx clock
SONET Rx Data
SONET Tx Data
M13 Rx clock
M13 Rx Data
M13 Tx Data
DS1/E1 Framer Loopbacks
Loopback
Framer
The loopbacks available in the DS1/E1 Framer block are shown in
drawing shows clock MUXes but not data MUXes to minimize clutter. The clock
source for each mode is listed in
Table 5-1. Clock Sources for DS1/E1 Loopback Modes
Framer
Line
Payload
Framer Loopback—All transmitted data is looped back to the receiver. This
loopback is activated by setting the Local Framer Loopback (FLOOP) bit in the
Loopback Configuration register [DS1/E1 Framer block, addr: 014].
Line Loopback—The line loopback loops the Receiver inputs to the Transmitter
outputs. The loopback provides BPV transparency and the ability to override the
looped data with AIS. The Receiver data path is not affected by the activation of
this loopback. The remote Line Loopback (LLOOP) is activated by setting the
Remote Line Loopback bit in the Loopback Configuration register [DS1/E1
Framer Block, addr: 014]. It is possible to operate the remote line loopback
simultaneously with Local Framer loopback.
Payload Loopback—This loopback only loops the received payload data back to the
transmitter. The overhead data is a continuous source from the transmitter. Because
the transmitting data is driven by the transmit clock, the received payload data
passes through a 64-bit a FIFO to accommodate receiver jitter (mainly introduced
by the VT mapper). This loopback is activated by setting the Unchannelized
Payload Loopback (UPLOOP) bit in the Loopback Configuration register [DS1/E1
Framer Block, addr: 014].
Loopback
Mindspeed Technologies™
Preliminary Information
DS1 or E1 reference clock
M13 or SONET Rx clock
M13 or SONET Rx clock
Receiver Clock Source
Line
Loopback
Transmitter
Receiver
Table
DS1/E1 Framer
5-1.
64-bit
FIFO
Payload
Loopback
DS1 or E1 reference clock
M13 or SONET Rx clock
DS1 or E1 reference clock
Transmitter Clock Source
Figure
TSB Rx Data
TSB Tx Data
5-2. The
Loopbacks
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