Long-Term Performance of a Space-System OCXO

Hudson, Andrew; Iyanu, G.; Wang, H.; Bloch, M.; McClelland, T.; Terracciano, Luigi

doi:10.1109/fcs.2019.8856101

Cited by 7 publications

(3 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Without a very high requirement on clock stability, most LEO satellites are equipped with oven-controlled crystal oscillators (OCXOs), or more practically, the temperaturecompensated crystal oscillators (TCXOs), which have a lower stability (Et Alia 2019). As shown in (Hudson et al 2019;Defraigne 2017), good OCXOs can also reach a short-term stability of 10 À 12 . The good stabilities of these frequency oscillators on-board LEO satellites have offered the possibility of short-term clock prediction with acceptable tolerance.…”

Section: Introductionmentioning

confidence: 89%

“…In this study, we follow the performance of a space-system OCXO studied in (Hudson et al 2019), with short-term stability of about 10 À 12 between 10 s and 100 s, and a randomwalk FM noise with a slope of about 0.5 from 100 s to 10000 s (see the red solid line in Figure 4). The frequency drift of the tested space-system OCXO in (Hudson et al 2019) has converged to about À 1:8 � 10 À 11 /day, which was also considered in the simulated OCXOs. This frequency drift, however, plays a less dominant role in the long-term than the randomwalk FM noise (see the red dashed line in Figure 4).…”

Section: Stability Of the Frequency Oscillatormentioning

confidence: 99%

See 1 more Smart Citation

LEO satellite clock analysis and prediction for positioning applications

Wang

El‐Mowafy

2021

Geo-spatial Information Science

View full text Add to dashboard Cite

The positioning service aided by low Earth orbit (LEO) mega-constellations has become a hot topic in recent years. To achieve precise positioning, accuracy of the LEO clocks is important for single-receiver users. To bridge the gap between the applicable time of the clock products and the time of positioning, the precise LEO clocks need to be predicted over a certain period depending on the sampling interval of the clock products. This study discusses the prediction errors for periods from 10 s to 1 h for two typical LEO clock types, i.e. the ultra-stable oscillator (USO) and the oven-controlled crystal oscillator (OCXO). The prediction is based on GNSSdetermined precise clock estimates, where the clock stability is related to the GNSS estimation errors, the behaviors of the oscillators themselves, the systematic effects related to the environment and the relativistic effects, and the stability of the time reference. Based on real data analysis, LEO clocks of the two different types are simulated under different conditions, and a prediction model considering the systematic effects is proposed. Compared to a simple polynomial fitting model usually applied, the proposed model can significantly reduce the prediction errors, i.e. by about 40%-70% in simulations and about 5%-30% for real data containing different miss-modeled effects. For both clock types, short-term prediction of 1 min would result in a root mean square error (RMSE) of a few centimeters when using a very stable time reference. The RMSE amounts to about 0.1 m, when a typical real-time time reference of the national center for space studies (CNES) real-time clocks was used. For longterm prediction of 1 h, the RMSE could range from below 1 m to a few meters for the USOs, depending on the complexity of the miss-modeled effects. For OCXOs, the 1 h prediction could lead to larger errors with an RMSE of about 10 m.

show abstract

Section: Introductionmentioning

confidence: 89%

Section: Stability Of the Frequency Oscillatormentioning

confidence: 99%

LEO satellite clock analysis and prediction for positioning applications

Wang

El‐Mowafy

2021

Geo-spatial Information Science

View full text Add to dashboard Cite

show abstract

“…Like the clocks of GNSS satellites, predicted LEO satellite clocks (see Section 2.2) can be fitted with low-order polynomials and provided to users. Due to the bad LEO satellite clock prediction behaviors over the mid-to long-term [38,39], broadcasting clock coefficients over low-frequency navigation messages like GNSS is not a good option for LEO satellites. It is suggested to either significantly increase the update rate of the broadcast clock messages, or transfer the clocks via real-time streams with the Internet.…”

Section: Leo Satellite Clock Broadcasting For Real-time Applicationsmentioning

confidence: 99%

Real-Time LEO Satellite Clocks Based on Near-Real-Time Clock Determination with Ultra-Short-Term Prediction

Wu,

Wang,

Wang

et al. 2024

Remote Sensing

View full text Add to dashboard Cite

The utilization of Low Earth Orbit (LEO) satellites is anticipated to augment various aspects of traditional GNSS-based Positioning, Navigation, and Timing (PNT) services. While the LEO satellite orbital products can nowadays be produced with rather high accuracy in real-time of a few centimeters, the precision of the LEO satellite clock products that can be achieved in real-time is less studied. The latter, however, plays an essential role in the LEO-augmented positioning and timing performances. In real-time, the users eventually use the predicted LEO satellite clocks, with their precision determined by both the near-real-time clock precision and the prediction time needed to match the time window for real-time applications, i.e., the precision loss during the prediction phase. In this study, a real-time LEO satellite clock determination method, consisting of near-real-time clock determination with ultra-short-term clock prediction is proposed and implemented. The principles and strategies of this method are discussed in detail. The proposed method utilized Kalman-filter-based processing, but supports restarts at pre-defined times, thus hampering continuous bias propagation and accumulation from ancient epochs. Based on the method, using Sentinel-3B GNSS observations and the real-time GNSS products from the National Center for Space Studies (CNES) in France, the near-real-time LEO satellite clocks can reach a precision of 0.2 to 0.3 ns, and the precision loss during the prediction phase is within 0.07 ns for a prediction time window from 30 to 90 s. This results in a total error budget in the real-time LEO satellite clocks of about 0.3 ns.

show abstract

Development and Research Progress of Crystal Oscillator

Yang

Xiang

2023

Lecture Notes in Electrical Engineering

View full text Add to dashboard Cite

Long-Term Performance of a Space-System OCXO

Cited by 7 publications

References 7 publications

LEO satellite clock analysis and prediction for positioning applications

LEO satellite clock analysis and prediction for positioning applications

Real-Time LEO Satellite Clocks Based on Near-Real-Time Clock Determination with Ultra-Short-Term Prediction

Development and Research Progress of Crystal Oscillator

Contact Info

Product

Resources

About