Telephone Time Service
For the realization of the legally binding Austrian standard time the BEV is operating a Caesium time and frequency standard (atomic clock). The time signal directly traceable to the national standard is transmitted in the form of second pulses via telephone line.
It is available in the public telephone network: +43 1 21110 821505.
A constant 50 ms tone of 1000 Hz is generated at the beginning of each second. Every new minute is announced by the suppression of the last pulse before this new minute. Furthermore the last 5 pulses before the beginning of the first minute of the next hour are suppressed. These second pulses can be used to set clocks or to calibrate microchronometers (stopwatches) for example.
Deviations, run times and measurement uncertainties:
BEV is continuously carrying out time comparisons with other institutes using GNSS-satellites. The second is realized with an accuracy that would result in a deviation of one second in one million years. The deviation of the Austrian Time Scale from the International Time Scale UTC is at all times kept below 100 ns.
The time signal transmitted via telephone line arrives time-delayed at the recipient. This time delay is always below 30 ms for all locations in Austria and her neighbouring countries. The delay has no influence on the determination of time intervals as long as the connection is not interrupted. If the connection was interrupted and restored later on, the new connection could use another path than the old connection. This can result in slightly different delays, whose variations will be irrelevant in most cases.
At the calibration of manually operated stopwatches the measuring uncertainties are practically solely caused by manually starting and stopping. Therefore any variations in delays can be neglected. A typical value for the measuring uncertainty caused by manually starting and stopping is 0,3 seconds.