Clocking in

It is often asked what the sampling rates are (160 or 200 megasamples per second) and how they are synchronised. For this, the station uses a rubidium atomic clock. This small, temperature stabilised unit provides a 10 MHz clock signal, from which phased locked loops can generate the required sampling frequency. The rubidium itself is synchronised long-term with a GPS 1 PPS (pulse-per-second).

The rubidium frequency standard in the KAIRA equipment racks. (Photo: D. McKay-Bukowski)

Although seemingly not much, this actually a very important part of the system and the monitoring of the stability and accuracy of it is an important part of the quality assurance programme of the station.