Enhanced timing accuracy for Cluster data
K. H. Yearby, S. N. Walker, М. А. Балихин · 2013 · 2 citationsRead the paper
Abstract. The standard timing accuracy for the Cluster mission is ±2 ms. However for inter-spacecraft comparisons of waveform data, a much higher accuracy is needed – for example a timing error of 1 ms results in a phase error of 65° for a signal at 180 Hz. Most Cluster data are recorded on an onboard solid state recorder and time-stamped using an onboard clock which is calibrated to coordinated universal time (UTC). Until recently, the error of this onboard clock was allowed to increase to the ±2 ms limit before a new calibration was applied. However, the timing error for real-time data is estimated to be only ~11 μs, so these data may be used to prepare a time correction data set which allows the standard timing accuracy to be improved considerably. This paper describes the details of the preparation and validation of this data set. Two independent source data sets are used: telemetry to European Space Agency (ESA) ground stations supporting the main operations of the Cluster spacecraft, and the real-time telemetry to the NASA Deep Space Network (DSN) stations supporting the Wide-Band Plasma Wave Investigation.
What the full text shows
Deployed in practice- Timing accuracy for Cluster data can be enhanced to the order of 20 μs using the TCOR data set. — ~20 μs vs. ±2 ms baseline (Applying corrections from the TCOR data set in the Cluster Science Archive)
- Change in ESOC procedure (new time correlation during every nominal pass) improved basic timing accuracy. — ~50 μs vs. 2 ms (Post-November 2007 procedure)
- Estimated timing error for real-time data is significantly lower than recorded data. — ~11 μs (Real-time telemetry data)
- Timing error of 1 ms causes significant phase error for high-frequency signals. — 65° phase error at 180 Hz (Inter-spacecraft waveform comparisons)
- Setup
- Telemetry data from ESA ground stations and NASA Deep Space Network (DSN) stations for the Cluster spacecraft mission.
- How
- The authors developed a time correction (TCOR) data set by using linear interpolation of the difference (DIFF) between spacecraft event time (SCET) derived from ground station receive times and the onboard clock. They also identified and corrected a telemetry-mode-dependent offset (OFFSET) between the reference pulse and the recorded onboard time.
- Limitations
- The OFFSET correction is only applicable to data recorded on board, not real-time data. · Accuracy is limited by spacecraft position uncertainty and ground station clock drift.
Summarized by Gemma 4 from the open-access full text · 8 Oct 2026. Read it