PM5380-BI PMC-Sierra, Inc., PM5380-BI Datasheet - Page 95

• Manufacturer Part Number: PM5380-BI
• Description: Network Interface, SATURN User Network Interface (8x155) Telecom Standard Product
• Manufacturer: PMC-Sierra, Inc.

Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC- 2010299, Issue 2
10.21.1
10.21.2
10.21.3
10.22 Receive APS Overhead Processor
10.22.1
APS Data Recovery Unit
The data recovery unit (DRU) recovers the data from the incoming 622Mbit/s APS serial
stream. The DRU adapts the 622.08 MHz free running clock from the CSU to recover the
incoming APS bit serial. In order for the DRU to lock to the incoming stream, the APS link
must be frequency locked to the CSU 622.08 MHz clock. Low frequency jitter, such as
temperature induced wander, may be tracked by the DRU. For more detailed APS jitter
performance refer to Table 38.
APS FIFO
The receive APS FIFO is a 16 byte FIFO which allows a receive APS link to tolerate low
frequency jitter. Since the DRU tracks low frequency phase variations around the 622.08 MHz
CSU clock derived from reference clock REFCLK, the APS FIFO synchronizes the APS data
stream to the local REFCLK domain. Further downstream processing of the APS stream is
performed on the REFCLK clock domain.
APS Serial to Parallel Converter
The APS Serial to Parallel Converter (SIPO) searches for the initial SONET/SDH framing
pattern in the receive APS stream, and performs serial to parallel conversion on octet
boundaries.
While out of frame, the SIPO block monitors the recovered APS data stream for an occurrence
of a A1 byte. The SIPO adjusts its byte alignment of the serial-to-parallel converter when three
consecutive A1 bytes followed by three consecutive A2 bytes occur in the data stream. The
SIPO informs the RAOP Framer block when this framing pattern has been detected to
reinitializes the RAOP to the new frame alignment.
While in frame, the SIPO maintains the byte alignment APS data stream until AROP declares
out of frame.
The Receive APS Overhead Processor (RAOP) provides frame synchronization, descrambling,
section level alarm and performance monitoring. The processor is similar to a Receive Section
Overhead processor (RSOP) except some features of the RSOP are not supported.
Framer
The Framer Block determines the in-frame/out-of-frame status of the receive APS stream.
While in-frame, the framing bytes (A1, A2) in each frame are compared against the expected
pattern. Out-of-frame is declared when four consecutive frames containing one or more
framing pattern errors have been received.
S/UNI®-8x155 ASSP Telecom Standard Product Data Sheet
Released
95