STANDARD PRODUCT
PM5365 TEMAP
DATASHEET
PMC-1991148
ISSUE 3
HIGH DENSITY VT/TU MAPPER
AND M13 MULTIPLEXER
individual serial bit rates and the available STS-1 or STM-1/VC3 payload
capacity. The asynchronous T1 mapping consists of 104 octets every 500 µs (2
KHz). The asynchronous E1 mapping consists of 140 octets every 500 µs (2
KHz). Refer to the RTDM block for a description of the asynchronous T1 and E1
mappings.
The tributary mapper is a time-sliced state machine which uses a payload buffer
as an elastic store. The T1 or E1 streams are read from the payload buffer, and
mapped into VT1.5 Payloads and VT2 Payloads using bit asynchronous
mapping only.
The Tributary Mapper compensates for phase and frequency offsets using bit
stuffing. A jitter-reducing control loop is used to monitor the Payload Buffer depth
and reduce mapping jitter to 1.0 UI. To reduce mapping jitter even further, a
dither technique is inserted between the control loop and the stuff bit generator
resulting in an acceptable desynchronizer mapping jitter of about 0.3 UI.
The Tributary Mapper may optionally act as a time switch. When Time Switch
Enable is active, the association of Tributary Mapper VT Payloads to logical FIFO
data streams is software configurable. There are two pages in the time switch
configuration RAM. One page is software selectable to be the active page and
the other the stand-by page. The configuration in the active page is used to
associate outgoing VT Payloads to logical FIFOs. The stand-by page can be
programmed to the next switch configuration. Change of page selection is
synchronized to incoming stream frame boundaries. When Time Switch Enable
is inactive, the association of outgoing VT Payloads to logical FIFOs is fixed.
The TTMP outputs the STS-1, TUG3 in a STM-1/VC4 or STM-1/VC3 with the bit
asynchronous mapped T1s or E1s onto an internal bus for further processing by
the Transmit Tributary Payload Processor block.
9.23 Serial In to Parallel Out Converter (SIPO)
The Serial In to Parallel Out Converter (SIPO) accepts serial data from up to 28
T1 or 21 E1 sources and converts these streams to byte serial format. The bytes
are passed to the Transmit Tributary Mapper (TTMP) for bit asynchronous
mapping into the STS-1.
9.24 DS3 Mapper ADD Side (D3MA)
The DS3 Mapper ADD Side (D3MA) block maps a DS3 signal into an STS-1
(STM-0/AU3) payload and compensate for any frequency differences between
the incoming DS3 serial bit rate (TICLK) and the available STS-1 (STM-0/AU3)
SPE mapped payload capacity. The asynchronous DS3 mapping consists of 9
rows every 125 µs (8 KHz). Each row contains 621 information bits, 5 stuff
Proprietary and Confidential to PMC-Sierra, Inc. and for its Customers’ Internal Use
95
PMC [ PMC-SIERRA, INC ]
