Time Transfer and Calibration in an EMI Sensitive Environment

• Published in: 2018 IEEE International Frequency Control Symposium (IFCS) pp. 1 - 5
• Main Authors: Gamatham, R., Boyana, L., Otto, A., van der Merwe, C., Burger, J. P., Matthee, C., Adams, G., Siebrits, R., Abbott, T., Kapp, F., Mnyandu, N., Tshongweni, S.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-05-2018
• Subjects: Clocks; Electromagnetic interference (EMI); Global navigation satellite system; global navigation satellite system (GNSS); Global Positioning System; Masers; MeerKAT; NMISA; Rabbits; Receivers; Timing; Travelling Receiver
• ISSN: 2327-1949
• DOI: 10.1109/FCS.2018.8597563

The MeerKaT telescope consists of 64 dishes with an Offset Gregorian optical layout where the main reflector has a 13.5 m diameter. The maximum baseline of these interlinked receptors is 8 km between dishes. Synchronization and timing is vital in the operation of this telescope. There are unique challenges involved with precision time transfer in environments where ultra-low interference (below -200 dBm/Hz) is required, near highly sensitive RF receivers. All electronic equipment including the MeerKAT clocks (Masers) operate within a radio frequency interference (RFI) sealed space. This forces an innovative new calibration strategy to be implemented. We present a unique calibration technique using fibre optics and a temperature stabilized global navigation satellite system (GNSS) receiver together with a time synchronization module in this article, for the first time to our knowledge. The Travelling receiver which is under development will be temperature stabilized, radio frequency interference (RFI) shielded and optically isolated. When complete the Travelling receiver will be calibrated at the National Metrology Institute of South Africa (NMISA). Thereafter the calibrated Travelling receiver will be used to calibrate the MeerKaT timing system. Using the Travelling receiver we are working towards calibrating the MeerKAT time transfer system delay (clock to GNSS delay) within ~3 ns. In this article we present key results towards the final product.