Time and frequency calibration via GPSFor calibration of more accurate time and frequency standards, we offer on-site calibration using the GPS satellite system as an intermediate reference. This requires installation of equipment for reception and storage of data from the GPS.
The method, known as GPS Common View, is similar to that used by RISE to provide international traceability.
We can also verify and calibrate the time synchronising and positioning performance of different types of GPS and GLONASS receivers.
On-site calibration using GPS
The method involves calibrating a frequency standard or clock (DUT) against UTC(SP) by means of simultaneous measurements of GPS satellite signals by both the customer and by RISE. The use of common satellites eliminates many of the common measurement errors. In addition, the changes that are observed in the time intervals [UTC(SP) – DUT] provide an estimate of the DUT frequency relative to UTC(SP).
The measured values registered by the customer can be transferred automatically to RISE over the Internet. Performance calculation is performed automatically by RISE with the results being sent to the customer by (for example) e-mail. How often this is done is agreed with the customer, but can in principle be done on a daily basis. The accuracy of frequency measurement, averaged over a day, is better than ±1E-13, but does depend on the quality of DUT.
All instrumentation needed (GPS receiver, time interval counter and computer) can be supplied by RISE.