RTK and PPK precision budget
The precision a receiver's a mm + b ppm specification promises over your baseline, horizontal and vertical, scaled to a confidence level and compared with your target.
Experimental: not yet fully verified. How results are checked
The spec gives 23 mm across at this range.
Provenance
- Computed by
- survey.gnss.rtk-budget 1.0.0, core 0.1.0
- Model
- Precision = a + b × 10⁻⁶ × baseline, the way receiver specifications state it (1σ, ideal conditions); at 95% the horizontal value is multiplied by 2.448 (the two-dimensional factor) and the vertical by 1.96
- Accuracy
- Manufacturer specifications assume open sky, good geometry, and no multipath; field results are often worse. A root-sum-square of the two terms would read lower
- Notes
- 1 shown with the answer
- Cites
- Henning, W., NOAA National Geodetic Survey, User Guidelines for Single Base Real Time GNSS Positioning
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Precision = a + b × 10⁻⁶ × baseline, the way receiver specifications state it (1σ, ideal conditions); at 95% the horizontal value is multiplied by 2.448 (the two-dimensional factor) and the vertical by 1.96
Show your work
Distance term
b × 10⁻⁶ × baseline1 × 10⁻⁶ × 15,000 m= 15 mmHorizontal precision
(a + distance term) × confidence factor(8 + 15) mm × 1= 23 mm
The same steps an agent gets from the MCP server with explain: true.
Accuracy: Manufacturer specifications assume open sky, good geometry, and no multipath; field results are often worse. A root-sum-square of the two terms would read lower
Worked example: 8 mm + 1 ppm over a 15 km baseline. Source: add-practitioner-essentials RTK scenario: 23 mm horizontal (a + b·d, as manufacturers state it). It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Baseline
- 15 km
- Horizontal a
- 8 mm
- Horizontal b
- 1
You get
- Horizontal precision
- 23 mm
Review: Not yet independently reviewed by a licensed surveyor.
Last verified: 2026-09-22, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 5 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- User Guidelines for Single Base Real Time GNSS Positioning, Henning, W., NOAA National Geodetic Survey, Version 3.1, April 2014. Page 25 (the baseline-dependent error: most manufacturers specify 1 ppm) and the localization section (stated RT accuracies such as 1 cm + 1 ppm horizontal at one sigma).
Terms
- PPK: post-processed kinematic
- Like RTK, but the corrections are applied after the survey, from logged base and rover data. Source: User Guidelines for Single Base Real Time GNSS Positioning
- RTK: real-time kinematic
- GNSS positioning corrected live from a base station or network, good to about a centimeter plus about a millimeter per kilometer from the base. Source: User Guidelines for Single Base Real Time GNSS Positioning
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.