Calibration of an optically isolated GNSS Traveling Calibrator

This article presents a global navigation satellite system (GNSS) Traveling Calibrator (TC) that transmits timing signals and feedback control signals over single mode optical fibre. The TC is a radio quiet instrument which emits very low radio frequencies. The main function of the TC is to calibrate GNSS receiver to antenna links based at radio telescopes that require minimum radio frequency emissions such as the MeerKAT radio telescope in South Africa. The TC was deployed at the MeerKAT site and calibrated using a MeerKAT global point positioning (GPS) station. A tailor-made proportional integral (PI) control system maintained the temperature of the TC within ±0.3°C from the set point over a 5 day observation period. The TC calibration values for the Pl and P2 codes were found to be 55.25ns and 54.90ns.