Geodetic Time Transfer terminal (GeTT).

This page will show information concerning an approximately one year test of GPS CP time and frequency transfer between the U.S. Naval Observatory (USNO), Washington, DC USA and the Physakalish-Technische Bundesanstalt (PTB), Braunschweig, Germany. The GeTT is on loan from the Swiss Office of Metrology and the Astronomical Institute of Bern, Switzerland, who designed and built the system pictured in figure 1. The GeTT system is built upon an Ashtech Z-12 receiver (GeTT).

GeTT Image.

Figure 1: Image of the location of the GeTT in its portable rack setup at USNO.
(USNO image - gif - 86 Kb)

GeTT Antenna Image.

Figure 2: Image of the location of the GeTT antenna at USNO.
(USNO image - gif - 277 Kb)

Figure 3: Basic system diagram for USNO TWSTT and GeTT.



                                                                    
                                 USNO GeTT                  / \     
                TWSTT                                      /   \    
             Link to PTB                                  /     \   
                            *                            /       \  
                    O       *                           /         \ 
                     \     *                           /           \
              **      \   *                            |-|-|-O-|-|-|
                ***____** TWSTT Ant.                         |      
                      |                                      |      
                      |                                      |      
-------------    -----|-----      -----------           ------------
|           |    |  USNO   |      |  USNO   |   5MHz    |   USNO   |
|  H-maser  |--->|  (MC2)  |----->|  (MC3)  |---------->|   GeTT   |
|  Source   |    |  (AOG)  |      |  (AOG)  |           |__________|
|___________|    |_________|      |_________|
Time and frequency transfer comparisons between the U.S. Naval Observatory Master Clock (USNO MC) and the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany (PTB) are being performed using three high precision methods. The methods being compared are GPS Common-View (GPS CV), GPS CP, and Two-Way Satellite Time Transfer (TWSTT). Several prime areas of study are to understand how to calibrate the three methods optimally and to understand differences and variability between the two methods.


REFERENCES

  1. Overney, Frederic (1997). "Geodetic Time Transfer Terminal", Short Technical Description dated September 9, 1997, A joint project Swiss Federal Office of Metrology and the Astronomical Institute of the University of Berne.


This page is http://tycho.usno.navy.mil/gpscp_gett.html
(24 April 1999)

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