Telecom
networks which are out of synchronisation often
suffer from bit errors and slow transmission rates.
Without precise timing, transmissions can lose
some information during transport, particularly
in the realm of optical transport data network
and broadband systems.
As new standards emerge in the world of mobile
telecommunications and digital broadcasting, the
high quality of the synchronisation signal becomes
increasingly important for cellular operators
and media centres.
The
OSA 5581C GPS is a GPS synchronisation receiver
and distributor specially designed to eliminate
these problems.
All critical parts in the OSA 5581C GPS, including
the GPS input & holdover unit, can be duplicated
to ensure high availability.
Input & Holdover
The
OSA 5581C GPS can be equipped with dual redundant
GPS input & holdover modules to provide unparalleled
reliability. Each module features one GPS receiver
and one auxiliary input reference accepting El
or T1 signals or an auto detected frequency (1.544,
2.048, 5 or 10 MHz).
Thanks to its modularity, the equipment can also
be configured with only one GPS input & holdover
module for extremely low cost applications; upgrading
to a fully-redundant dual channel solution at
a later stage is made possible by simply inserting
the necessary modules in their slots.
In cases where all GPS signals and external sync
inputs are lost, the internal oscillator goes
into holdover mode so as to then deliver both
frequency and time-of-day information autonomously.
In holdover mode, the frequency output shows a
frequency drift better than 1x10e-10 / day (OCXO)
or 5x10e-11 / month (Rb).
Output & Re-timing
Besides
being a top-quality GPS receiver with holdover
capability, the OSA 5581C GPS provides also, in
the same box, synchronisation distribution and/or
re-timing, avoiding the need for separate equipment
(and additional management connections).
It can provide up to 64 output synchronisation
signals of telecom formats (E1, T1, and/or various
frequencies), up to 24 E1/T1 re-timing channels
or a combination of outputs and re-timing.
Time Code
Finally, the OSA 5581C GPS can be fitted with an NTP module to obtain a Stratum 1 NTP server providing accurate, GPS referenced time information on IP networks, and further taking advantage of the existing dual redundant GPS reference.
To add NTP functionality you just have to fit an NTP module in your OSA 5581C GPS: compare this elegant approach with the burden of installing another separate GPS receiver with its expensive GPS antenna and cabling; moreover, you also benefit of a high quality oscillator in case of GPS failure.
Besides NTP, other timing protocols can be made available on request.
There
are many applications for the OSA 5581C GPS:
It is ideal as a low cost ITU-T G.811 Primary Reference Clock / GR-2830-CORE
Stratum 1.
Its excellent internal oscillators attenuate the GPS-specific jitter & wander and deliver a frequency signal which meets ITU-T G.811
/ GR-2830-CORE, even under harsh temperature conditions.
A GPS receiver that is used as the central PRC
of an SDH- or SONET-based synchronisation network
is required to have a high availability. Dual
GPS receiver configuration is the appropriate
solution for this application.
OSA 5581C GPS can also be used as a telecom node
clock to synchronise networks based primarily
on GPS as a means to distribute synchronisation.
Node clocks distribute synchronisation to all
telecom equipment in their building or node, e.g.
ADMs and DXCs in SDH or SONET network, digital
switches, ATM switches. ITU-T G.811 / GR-2830-CORE
performance is a prerequisite in nodes with international
switches.
A GPS-based synchronisation distribution does
not require the same complex synchronisation distribution
plan, as it is the case with conventional SDH-
or SONET-based master/slave distribution. A distributed
synchronisation plan architecture greatly simplifies
the design and the maintenance of the synchronisation
networks.
Some telecom equipment also requires time-of-day
information for e.g. billing and time-stamping.
The OSA 5581C GPS provides all the necessary output
time signals. The UTC-locked phase signal is useful
in mobile networks, where base transceiver stations
can be frame synchronised for better handover
performances.
Information
