Synchronet – an innovative system

Jul 2008 | No Comment

Franco Gottifredi, Monica Gotta, Enrico Varriale, Daniele Cretoni 

SynchroNet is a GNSS based time and frequency transfer system that allows to exploit high accuracy synchronization of accurate clocks

Implementation and Test Results

The main issue is the validation of SynchroNet core synchronization algorithms in their many components: ionospheric and tropospheric models implementation, code (i.e. pseudorange: Code and Phase) based CommonView, phase based CommonView (L1 and L2), clock stability characterization by mean of CV and comparison to direct synchronization in lab (PPS biases analysis).

IGS was selected as a test bench for algorithms validation thanks to the
wide set of products available allowing a significant statistical analysis.

Here after are presented some results of both validation test results and of performance assessment of SynchroNet algorithms.


SynchroNet is at its v1.0 verification phase but its kernel is already running as core service for the Galileo Test Range (GTR), an advanced research facility for the experimentation and analysis of the Galileo Signal, for testing and certification of user terminals and support services for the development of application services. In the frame of this project, SynchroNet is used for synchronization of pseudo satellites
OCXO driven Rubidium clocks used for ranging measurements with a requirement of 5ns ( ~1.5m) 1σ accuracy. In this context the main reference time (MRT0) is a free running Active Hydrogen Maser atomic clock while Control center features are customized and integrated in
the Control centre facility of the GTR.


SynchroNet is a GNSS based time and frequency transfer System that
allows to exploit high accuracy (nanoseconds and picosends level) synchronization of accurate clocks over large baselines by wrapping the
synchronization service in a robust and flexible infrastructure providing
security and scalability features.

Through separated and successful validation campaigns using IGS network and in a full deployed system (the GALILEO Test Range), SynchroNet has proven its customizability and performances.

Currently SynchroNet is going through a further design and research
phase in order to consolidate and expands its features at infrastructure
level to match critical systems requirements in order to become a high performance synchronization solution for every applicative domain.


D. W. Allan, M. 1) A. Weiss, “Accurate Time and Frequency Transfer During Common-View of a GPS Satellite”, 34th Annual Frequency Control Symposium, pp. 334-346, May 1980.
2) V. S. Zhang, T. E. Parker, M. A. Weiss, F. M. Vannicola, “Multi-Channel GPS/GLONASS Common-View between NIST and USNO”, IEEE International Frequency Control Symposium, pp. 598-606, June 2000.
3) M. A. Lombardi, L. M. Nelson, A. N. Novick, V. S. Zhang, “Time and
Frequency Measurements Using the Global Positioning System”, Cal. Lab. Int. J. Metrology, pp. 26-33, (July-September 2001).
4) D.B. Sullivan, D.W. Allan, D.A. Howe, F.L. Walls, “Characterization
of Clocks and Oscillators”, NIST Technical Note 1337, Mar. 1990
5) K.M.Larson J.Levine, “Carrier-Phase Time Transfer”, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control vol.
46, pp.1001-1012, Jul. 1999
6) E.Varriale, M. Gotta, F.Gottifredi, F. Lo Zito, “Common-View Technique Application: an Italian use case”, Tyrrhenian International Workshop on Digital Communication 2006,
Island of Ponza (Italy)

Franco Gottifredi

Head of the Navigation Systems, Augmentations &
Interoperability Unit in Thales Alenia Space.

Monica Gotta

Responsible for Thales Alenia Space Italia, of
the System Engineering activities as part of
System Integration and Verification Contract of
Galileo Phase C/D/E1.

Enrico Varriale

System Simulation Engineer for the Navigation
Integrated Communication Business Unit.

Daniele Cretoni

System Engineer in the Department of Navigation
and Integrated Comms B.U. of Thales Alenia Space
His Coordinates
Steve Berglund
Mark your calendar
May 09 TO DECEMBER 2009

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