1. Collaboration between DTAG, PTB and AGH Time & Frequency Dissemination SDH Bremen UTC(DTAG) Braunschweig UTC(PTB) 76,9854,2 47,89 44,3 Objectives:  Enable time comparison between (German) UTC-labs using optical fiber: here: PTB-DTAG  DTAG: feasibility study of installed telecom fiber for time dissemination  Dissemination of „traceable“ time UTC(x)  Investigating and pushing the limits of TTOF

2. Lopped setup – source of signals and measurements in Braunschweig 1 pps is measured with Time interval counter TIC resolution ≈10 ps @ 1s 10 MHz is measured with K&K counter (  -Mode) Counter resolution <200 fs @ 1s enhanced by dual mixer method Additional tapping module in Bremen allows for singal extraction Sliwczynski, L.; Krehlik, P., "Multipoint joint time and frequency dissemination in delay-stabilized fiber optic links," in Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on, vol.62, no.3, pp.412-420, March 2015 Additional tapping module in Bremen allows for singal extraction Sliwczynski, L.; Krehlik, P., "Multipoint joint time and frequency dissemination in delay-stabilized fiber optic links," in Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on, vol.62, no.3, pp.412-420, March 2015

3. First preliminary results

5. Dual-Mixer Time Difference Methode with Harmonic Tracking  N LPF VCO Synthesizer 10.250000 Hz Time Interval TIC 4100  N LPF VCO FXE Counter Ch 1 Ch 2 Ch 3 Ch 4 10.000000 Hz 1 PPS 10.000000 Hz 0dB N= 128 LPF 1.9 MHz N= 128 Local site Remote site