1. Collaboration between Deutsche Telekom AG (DTAG), AGH1 University of Science and Technology, and PTB Time & Frequency Dissemination
SDH
Bremen UTC(DTAG)
Braunschweig UTC(PTB)
76.98 km
54.2 km
47.89 km
44.3 km
Objectives:
Enable time comparison between (German) UTC-labs using optical fiber: here: PTB-DTAG
DTAG: feasibility study of installed DTAG-telecom fiber for time dissemination
Dissemination of „traceable“ time UTC(x)
Investigating and pushing the limits of Time Transfer over Fiber (TTOF)
1Akademia Gorniczo-Hutnicza im. Stanislawa Staszica w Krakowie (AGH)

2. Looped setup – source of signals and measurements in Braunschweig
SPBA: single path bi-directional amplifier
Additional tapping module in Bremen allows for signal 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 , March 2015
10 MHz is measured with K&K counter (L-Mode)
Counter resolution <200 1s
enhanced by dual mixer method
1 pps is measured with Time interval counter
TIC resolution ≈10 1s

3. Preliminary results

4. Preliminary results

5. Dual-Mixer Time Difference Methode with Harmonic Tracking
Local site
Time Interval TIC 4100
Remote site
1 PPS
1 PPS Hz Hz
Synthesizer Hz
0dB
LPF 1.9 MHz
LPF 1.9 MHz
N= 128
N= 128
 N
 N
FXE Counter
VCO
VCO
Ch1
Ch2
Ch3
Ch4
LPF
LPF

6. Participants PTB: Dirk Piester Andreas Bauch Harald Schnatz
With support from
Harald Dietl
Holger Seifert
DTAG:
Helmut Imlau
Uwe Habighorst
Marvin Barasi
AGH:
Łukasz Sliwczynski
Przemysław Krehlik
With support from
Jacek Kolodziej