Single-Point Positioning
Compute a GNSS receiver position from a RINEX observation file and a broadcast navigation file, entirely in your browser. Weighted least-squares with satellite-clock, relativistic, Sagnac and tropospheric corrections, per-constellation clock offsets, DOP and outlier rejection.
Single-Point Positioning FAQ
- What is single-point positioning (SPP)?
- Single-point positioning computes a receiver’s absolute position from one epoch of pseudorange measurements and the satellites’ broadcast ephemerides, using weighted least squares. It is the fundamental GNSS positioning mode and typically achieves metre-level accuracy.
- What files do I need?
- A RINEX observation file (containing pseudoranges — plain RINEX, Hatanaka-compressed .crx, and gzip .gz are all accepted) and a broadcast navigation file (BRDC) covering the same day. Both are parsed entirely in your browser; nothing is uploaded.
- How accurate is it?
- This solver models satellite clocks (including the relativistic term), the Sagnac effect, and a simple troposphere, and rejects outliers. On single-frequency data expect roughly 5–30 m depending on ionospheric conditions and constellation mix; dual-frequency ionosphere-free processing reaches a few metres.
- Why is my position a few metres off the marker coordinates?
- SPP is inherently metre-level: it does not model the ionosphere on single-frequency data, uses broadcast (not precise) orbits and clocks, and has no carrier-phase ambiguity resolution. The “error vs header” figure compares against the APPROX POSITION in the RINEX header, which itself is only approximate for many receivers.