Atomic Clocks

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Laboratory for Time and Frequency

The operation of geodetic space techniques VLBI and SLR need most precise reference frequencies and time information. Atomic clocks work on the base of eigenfrequencies of specific atomes as oscillators. The time information is derived from counted oscillations periods.

Two different atomic clocks are necessary:

  • short time stable hidrogen-maser for time intervals in VLBI and SLR (Allan-variance 10^-15)
  • longterm stable cesium frequency normals (Allan variance 10^-13) for time keeping and as time scale for SLR measurements.

The relative accuracy of a cesium normal corresponds to an error of 1 second in 300.000 years.
Special GPS-time-receivers are usd for the tie of a lokal generated time scale. They provide a synchronisation with remote time keeping laboratories with a relative accuracy of about 10¯8 s.

Time Scale in TIGO

The time laboratory of TIGO contains 2 hidrogen-maser, 2 cesium frequency normals and 2 GPS-time-receivers. The time scale of each individual oscillator is measured periodically each 3 hours against the others. Offsets and drifts are hence discovered and controlled. These measurements are reported weekly to the Bureau International de Poids et Mesures in Paris for the generation of the world time scale UT (Universal Time).
The atomic clocks of TIGO are the first ones in Chile which had been aproved by the BIPM for the realisation of UTC.

International Time Service UT: http://www.bimp.fr