XRT75R03D_06 Datasheet, PDF (94/135 Pages) Exar Corporation – EXAR DATA SHEET FORMAT TEMPLATES

XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER REV. 1.0.4
• The Mapper will then terminate these STS-1 or VC-3 signals and will de-map out this DS3 or E3 data from
the incoming STS-1 SPEs or VC-3s, and output this DS3 or E3 to the DS3/E3 Facility-side towards the
XRT75R03D
• This DS3 or E3 signal (as it is output from these Mapper devices) will contain a large amount intrinsic jitter
and wander due to (1) the process of asynchronously mapping a DS3 or E3 signal into a SONET or SDH
signal, (2) the occurrence of Pointer Adjustments within the SONET or SDH signal (transporting these DS3
or E3 signals) as it traverses the SONET/SDH network, and (3) clock gapping.
• When the XRT75R03D has been configured to operate in the "SONET/SDH De-Sync" Mode, then it will (1)
accept this jittery DS3 or E3 clock and data signal from the Mapper device (via the Transmit System-side
interface) and (2) through the Jitter Attenuator, the XRT75R03D will reduce the Jitter and Wander amplitude
within these DS3 or E3 signals such that they (when output onto the line) will comply with the above-
mentioned intrinsic jitter and wander specifications.
10.1 BACKGROUND AND DETAILED INFORMATION - SONET DE-SYNC APPLICATIONS
This section provides an in-depth discussion on the mechanisms that will cause Jitter and Wander within a
DS3 or E3 signal that is being transported across a SONET or SDH Network. A lot of this material is
introductory, and can be skipped by the engineer that is already experienced in SONET/SDH designs. In this
case, the user should proceed directly to “Section 10.8, Designing with the XRT75R03D” on page 120,
which describes how to configure the XRT75R03D in the appropriate set of modes in order to support this
application.
In the wide-area network (WAN) in North America it is often necessary to transport a DS3 signal over a long
distance (perhaps over a thousand miles) in order to support a particular service. Now rather than realizing
this transport of DS3 data, by using over a thousand miles of coaxial cable (interspaced by a large number of
DS3 repeaters) a common thing to do is to route this DS3 signal to a piece of equipment (such as a Terminal
MUX, which in the "SONET Community" is known as a PTE or Path Terminating Equipment). This Terminal
MUX will asynchronously map the DS3 signal into a SONET signal. At this point, the SONET network will now
transport this asynchronously mapped DS3 signal from one PTE to another PTE (which is located at the other
end of the SONET network). Once this SONET signal arrives at the remote PTE, this DS3 signal will then be
extracted from the SONET signal, and will be output to some other DS3 Terminal Equipment for further
processing.
Similar things are done outside of North America. In this case, this DS3 or E3 signal is routed to a PTE, where
it is asynchronously mapped into an SDH signal. This asynchronously mapped DS3 or E3 signal is then
transported across the SDH network (from one PTE to the PTE at the other end of the SDH network). Once
this SDH signal arrives at the remote PTE, this DS3 or E3 signal will then be extracted from the SDH signal,
and will be output to some other DS3/E3 Terminal Equipment for further processing.
Figure 31 presents an illustration of this approach to transporting DS3 data over a SONET Network
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