SYNCNET

Picosecond Synchronization System

for Long Distance Time / Frequency Transfer

and Digital Receiver for Long Baseline Phased Arrays

(industrialization stage)

The SyncNet system allows a precise time / frequency transfer through optical fibers towards client sub-systems, which were originally digital antennas. The transfer is done by synchronization stations which broadcast the time information on multiple ports.

Although studied with low cost optical modules (ethernet SFP modules) for antenna arrays of several hundreds meters, SyncNet is usable for links to several tens of kilometers with an absolute error of less than a few tens of picoseconds.

While having similarities with well-known "White Rabbit" systems and future revision of Ethernet PTP (IEEE1588, Precision Time Protocol), SyncNet is specifically dedicated to synchronization (data transfer is minor) and such allows much more stability and precision.

A first client subsystem is a HF digital receiver for large arrays, aimed to digitization at the antenna, for SDR (Software-Defined Radio) in a MIMO (Multiple Inputs Multiple Outputs) context, core of a HF digital antenna with full-band digitizer and integrated channelizer with direct broadcast on ethernet fiber and self-calibration.

Example of measurement (lab): 160 h delay shift variation between two digital receivers synchronized to a SyncNet station through 7 km fibers (ADEV: Allan deviation, MDEV: modified Allan deviation, TDEV: time deviation):