A detection algorithm of frequency jumps for GNSS satellite clocks
As the frequency and time reference of space satellites, satellite clock has a direct influence on GNSS service performance. Any anomaly of the atomic clock behavior on board the satellites causes errors for user position. Therefore, it is necessary to detect clock anomaly. Frequency jumps are one of the most common anomalies in atomic clocks of on-board satellites, which appear due to space radiation, temperature change and other factors. In this paper, a detection algorithm of frequency jumps based on the batch least squares residues is proposed. Performance of the new algorithm is analyzed and verified by numerical simulation. The detection algorithm of frequency jumps for satellite clocks proposed in this paper is helpful to GNSS satellite clock autonomous integrity monitoring.
The dynamic Allan variance
We present and discuss the dynamic Allan variance, a measure of the time-varying stability of an atomic clock. First, the dynamic Allan variance is mathematically defined, then its behavior is extensively tested on simulated and experimental data. The results prove the validity and the effectiveness of the proposed new tool.
The Selection and Use of Precise Frequency and Time Systems
Abstract : The ITU-R has authorized the creation of a handbook, "The Selection and Use of Precise Frequency and Time Systems." This handbook is designed for use by the beginner in the field and for undeveloped countries that wish to establish a national laboratory or calibration laboratory. The lack of such a handbook is serious, so the ITU has decided to generate one. The editor, Richard L. Sydnor, and the assistant editor, David Allan, have selected authors for the various chapters from experts in the field and have correlated and generated the various drafts for the final version.