VLBI and GPS-based Time-transfer Using CONT08 Data

One important prerequisite for geodetic Very Long Baseline Interferometry (VLBI) is the use of frequency standards with excellent short term stability. This makes VLBI stations, which are often co-located with Global Navigation Satellite System (GNSS) receiving stations, interesting for studies of time- and frequency-transfer techniques. We present an assessment of VLBI time-transfer based on the data of the two week long consecutive IVS CONT08 VLBI campaign by using GPS Carrier Phase (GPSCP). CONT08 was a 15 day long campaign in August 2008 that involved eleven VLBI stations on five continents. For CONT08 we estimated the worst case VLBI frequency link stability between the stations of Onsala and Wettzell to ¼ 1e-15 at one day. Comparisons with GPSCP confirm the VLBI results. We also identify time-transfer related challenges of the VLBI technique as used today.

[1]  P. Tavella,et al.  Experimental assessment of the time transfer capability of precise point positioning (PPP) , 2005, Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005..

[2]  Thomas A. Clark,et al.  Measurement of horizontal motions in Alaska using very long baseline interferometry , 1990 .

[3]  Thomas Hobiger,et al.  VLBI Measurements for Time and Frequency Transfer , 2008 .

[4]  Eiji Kawai,et al.  The first comparative experiment of VLBI and two-way time transfer with better than 1 nsec precision , 1994, Conference Proceedings. 10th Anniversary. IMTC/94. Advanced Technologies in I & M. 1994 IEEE Instrumentation and Measurement Technolgy Conference (Cat. No.94CH3424-9).

[5]  S. Hama,et al.  Development of VLBI time transfer system toward 0.1 nsec accuracy using transportable ground terminal for calibration , 1994, Conference Proceedings. 10th Anniversary. IMTC/94. Advanced Technologies in I & M. 1994 IEEE Instrumentation and Measurement Technolgy Conference (Cat. No.94CH3424-9).

[6]  John H. Spencer,et al.  Comparison of VLBI, TV, and Traveling Clock Techniques for Time Transfer , 1981 .

[7]  Jun Amagai,et al.  Japan-US time comparison experiment for realizing better than 1-ns accuracy by using a radio interferometric technique , 1989 .