PORG Analysis Centre
Pre-Published GNSS Clock and Orbit Predictions for Connectivity-Independent Real-Time PPP
Operational Product Characteristics
- Clock Stability: ~0.35 ns STD (24 h)
- Radial Orbit Agreement: ~5 cm RMS
- Data Completeness: 100% (no missing epochs)
- Epoch Interval: Down to 1 second
- Formats: SP3 + optional RINEX CLK
- Satellite Coverage: ~50 GPS/Galileo/GLONASS PRNs
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High-Accuracy GNSS Orbit and Clock Predictions for Real-Time PPP
Independent PPP testing has demonstrated stable rapid PPP solutions using PORG SP3/CLK products.
- 100% data availability — no missing epochs, reduced dependence on continuous real-time correction streams
- Immediate precise-state availability — no dependency on correction-stream startup
- Flexible temporal resolution — configurable down to 1 sec
- Precomputed SP3 and RINEX CLK products — available prior to first prediction epoch
PORG Scientific Evaluation — ESA GNSS 2026
PORG's GNSS prediction research was selected for an oral presentation at the
10th International Colloquium on Scientific and Fundamental Aspects of GNSS, chaired by the European Space Agency (ESA), held in Montréal, Canada, in October 2026.
The accompanying technical paper presents the capabilities and measured performance of the operational PORG v5.0 GNSS clock and orbit prediction service, with particular emphasis on satellite-clock stability and connectivity-independent real-time PPP.
The paper evaluates complete 24-hour SP3/CLK predictions, available before their first prediction epoch, with five-second sampling and independently valid 00:00 and 12:00 UTC releases. This approach supports real-time PPP applications without requiring continuously delivered precise correction streams.
Key Findings from GPS Week 2443
- High satellite-clock stability: PORG achieved 0.250 ns clock-error STD versus 0.435 ns for broadcast navigation, with 0.075 m PPP-oriented SISRE STD versus 0.154 m. Results use matched GPS/Galileo satellite-epochs with 12-hour satellite-offset removal.
- 41.8% lower GPS ranging RMS than broadcast navigation: 0.341 m for PORG versus 0.586 m for reconstructed GPS broadcast navigation, evaluated on identical satellite-epochs.
- 0.322 m GPS/Galileo SISRE RMS relative to CODE Rapid, following retrospective reference-clock alignment.
- Up to 47.3% lower multi-constellation ranging RMS than broadcast navigation: Best observed daily result, achieved on Day 308 using GPS, Galileo and selected GLONASS satellites.
- Consistent performance advantage: PORG outperformed the matched broadcast navigation baseline on every evaluated day in the GPS-only and combined multi-constellation comparisons.
- Continuous 24-hour prediction coverage: Independently valid 00:00 and 12:00 UTC SP3/CLK products support locally stored satellite-state processing without continuous internet access or real-time correction streams.
These findings demonstrate the accuracy, sustained clock stability and operational potential of PORG's prepublished predictions for real-time PPP. SISRE and clock-stability measurements characterise satellite-state performance rather than directly measured receiver positioning accuracy.
Download the PORG ESA GNSS 2026 Technical Paper (PDF)
Full methodology, performance analysis, operational characteristics and scientific limitations are provided in the paper.
Download Live PORG Predictions — Products Page