Multi-channel real-time computation of ADEV and TDEV

In this paper the methods of multi-channel real-time computation of ADEV and TDEV are proposed. These methods are developed for a multi-channel measuring system, where the time error counter and the computer controlling the measurement are two separate units. In order to calculate the parameters simultaneously for several channels and several observation intervals in the real time, all necessary operations should be performed in the time period between two sampling instants. Multichannel real-time computation requires the same rearrangement of estimators´ formulae, as for single-channel real-time computation. However, multichannel computation requires a special organization of the process because of multiple data streams received from several time error meters (measurement channels). In the paper the results of experimental tests of the methods proposed for different conditions are presented. The calculations were performed for the time error samples taken with sampling interval τ0=1/30 s, which is often used in the telecommunication applications. Different numbers, lengths, and ranges of the observation intervals simultaneously analyzed were considered. The results of calculation performed for data obtained from up to 4 channels using different computers are presented and compared. Two data organization methods, with separate data structures (one for each channel) and joint data structure, were considered and compared.