In contrary to standard two-way systems, our solution delivers stabilized and calibrated replica of source signals, thus may be described as a virtual atomic clock at the end of the fiber. Besides metrological applications, as clock comparisons, the system may be used for time and frequency distribution to the users not maintaining their own clocks.
The unique features of the system are based on the concept of active compensation of variations of the fiber delay. The signal reaching the remote module is redirected backward to the local module and used for compensation of path delay fluctuations.
Calibration of the time transfer is based on round-trip delay measurement, which is performed locally at the transmitting side of the system. After installation and initial calibration the input – output delay is constant and there is no need for any further measurements or data exchange.
Frequency signal: 10MHz (5 MHz, 100MHz options)
Time signal: 1PPS, 100PPS, 1000PPS (phase synchronous with frequency signal)
Optical fiber: one singlemode fiber of any type, APC connectors
Maximum optical attenuation: 25 dB (equivalent to 50 - 100 km of fiber, depends on link quality)
Delay correction range: 110 ns (enough for 100 km of fiber in typical environmental conditions)
Frequency transfer stability: ADEV < 1x10-12 for 1 s averaging, < 3x10-17 for 105s averaging
Time transfer stability: TDEV < 3 ps for 10 s averaging, < 1 ps for 105 s averaging
Time calibration uncertainty: 15 ps
|Time deviation of 1PPS transfer over 60 km-long urban fiber.||Allan deviation of 10 MHz transfer over 60 km-long urban fiber.|
Dedicated optical amplifiers and extended compensation range for long-haul installations up to 1000 km.