The source of time and frequency, synchronized from Global Positioning
System GPS (STFS/GPS model)
The STFS/GPS time and frequency source,
designed and constructed in the Institute of Electronics and Telecommunications,
Poznan University of Technology, is a high-class, specialised device
providing the International Time Scale UTC (Universal Time Coordinated)
and several synchronous signals with standard frequencies, synchronized
to GPS. The frequencies mentioned are the following: 1Hz, 50Hz, 1kHz,
2048kHz, 5MHz, and 10MHz. Six independent telecommunication outputs
for 2048kHz signal with parameters satisfying the ITU-T G.703-13 standard
(former G.703-10) enables simultaneous, direct synchronization of
up to six telecommunication devices, e.g. digital exchange, SDH multiplexers,
etc. Additionally, the STFS/GPS has lpps output installed for the
lpps signal control. The 1pps signal is received directly from an
external GPS receiver. It is also possible to equip STFS/GPS with
other frequency sets, e.g. 1Hz, 50Hz, 1kHz, 10kHz, 100kHz, 1MHz. The
2048kHz signal may be additionally split to many independent output
signals by means of DST distributors. The SFTS/GPS assures the accordance
of a locally generated time scale with the UTC with error less than
±200ns for lpps GPS output, and 1Hz of the local oscillator
(99,99% observation time), and less than ±500ns for other outputs.
The long-term frequency error is less than 8×10e-13 (level Stratum
1), independently of the receiver localization on the Earth.
The SFTS/GPS device is synchronized from the GPS satellite system
or, optionally, from other source, e.g. from a telecommunication network,
GLONASS receiver, etc. The distance between a GPS antenna and STFS/GPS
devices may be equal up to 150m in standard version. The SFTS/GPS
source may play the role of PRC clock or SSU clock, providing time
and synchronization signal to telecommunication stations, power stations,
security systems, information systems, etc.
The SFTS/GPS source is available in four classes: class A - including
internal rubidium oscillator with monthly frequency stability better
than 5×10e-11 per month and daily frequency stability better than
3×10e-12 per day; class B - including internal quartz oscillator with
daily frequency stability better than 2×10e-11 per day; class C -
including internal quartz oscillator with daily frequency stability
better than 1×10e-10 per day; class D - including internal quartz
oscillator with daily frequency stability better than 1×10e-9 per
day.