Real time monitoring and failure prediction of cesium atomic frequency standard at continuously operating reference stations

Atomic clocks are the major source to obtain accurate and stable frequency signals and thereby are the one of the best time keepers available in today's world. The applications of atomic clocks are numerous like precise time keeping, Banking, Power sectors, Satellite Navigation, Communications Networks etc. Cesium based atomic clock have crucial role in Satellite Navigation applications due to its better long term stability compared to other atomic clocks. In view of this a method is proposed in this paper for real time monitoring and failure prediction of Cesium Atomic clock housed in Continuously Operating Reference Station (CORS) having redundant chains to ensure availability and integrity of the station data. In Reference ground station housing multiple chains uses Reference Receiver meant for ranging which is driven by its respective Reference source for frequency and timing signals. Here two Reference receivers, meant for one way ranging of Navigational satellite are used which is driven by its respective cesium frequency standard (CFS). A phase comparator is used to provide phase measurements between CFS which sources as a frequency reference for each chain. The range measurements from each receiver and phase measurements from phase comparator are near synchronously logged and analyzed to correlate events in Real time and to quantify the misbehaviour of frequency source from any of the CFS. Analysis involves processing the Pseudo ranges to estimate range residues, range rates, standard deviations from code and carrier measurements, and processing the phase data from phase comparator to detect any phase jumps and also to compute stability for a pair of clocks. Also the telemetry parameters of CFS is closely monitored and compared with its allowable limits. The long term trend analysis of the CFS system parameters values will infer about the behaviour and any chances of future failure.