Online GNSS data analysis and observation quality inspection
Audit GNSS observation files before running high-precision positioning. Measure cycle slips, multipath errors, signal strength, and tracking continuity across all 5 satellite constellations.
Before you process, find out whether the data holds up.
Quick check, no account
Upload an observation file or open a sample to see its quality score and key findings.
One file up to 100 MB (20 MB gzipped), ten checks per day. The file is deleted as soon as the result is ready.
Choose a file first
No file? Use a public station
Opens a stored example result straight away and does not use one of your daily checks.
Fetches a station's daily observation file from the public archives and checks it. It needs the person check above and uses one of your daily checks.
Why GNSS data analysis is essential before post-processing
Feeding unvetted observation data into high-precision positioning software leads to failed ambiguity resolution, undetected cycle slip propagation, and distorted coordinate baselines. PosFlow Crux provides automated GNSS data analysis in seconds, ensuring your field data is healthy, complete, and reliable before proceeding with downstream computation.
Key metrics evaluated during GNSS data analysis
- Observation Completeness: Evaluates observed vs expected epochs based on the nominal recording interval across all tracking channels.
- Multipath Estimation: Uses pseudorange and dual-frequency carrier-phase linear combinations (MP1, MP2, MP5) to quantify local reflective interference.
- Cycle Slip Detection: Identifies carrier-phase tracking interruptions and calculates the cycle slip ratio (epochs per slip).
- Signal Strength (SNR / C/N0): Maps signal-to-noise ratios across satellite elevation angles to uncover antenna obstruction or RF interference.
- Receiver Clock Behavior: Tracks clock jumps, drift rate, and millisecond time-tag irregularities.
0-100 composite quality scoring methodology
PosFlow synthesizes complex raw measurements into an intuitive 0-100 quality score weighted by observation completeness (35%), multipath suppression (30%), cycle slip resistance (25%), and signal strength (10%). Scores are classified into Excellent (90+), Good (75-89), Fair (60-74), Poor (40-59), and Critical (<40).
Modern replacement for legacy command-line tools
Unlike legacy command-line tools that halted maintenance years ago and fail on modern RINEX 3/4 multi-frequency signals (such as BeiDou B1C/B2a or Galileo E5), PosFlow provides cloud-native execution with zero local installation, interactive visual charts, and downloadable audit reports.
How to perform GNSS data analysis online
Quickly inspect and audit GNSS observation quality in 4 simple steps.
Upload RINEX or raw log
Upload any RINEX 2.x, 3.x, 4.x observation file or native receiver log (UBX, SBF, Trimble, Leica).
Automated header and constellation parsing
The system validates file structure, detects constellations (GPS, GLO, GAL, BDS, QZSS), and identifies signal frequencies.
Run multi-frequency quality audit
The cloud analysis engine computes epoch completeness, cycle slip counts, MP1/MP2 multipath values, and SNR distribution.
Review quality score and export report
Inspect the 0-100 composite score, review satellite skyplots and tracking charts, and export the findings as PDF or CSV.
What won't produce a result
Worth checking before you upload, so a run doesn't cost you credits to tell you what your data was missing.
Observation files without observation data records or invalid epoch headers
Standard RINEX observation records containing valid pseudorange and carrier-phase measurements for analysis.
Navigation-only ephemeris files uploaded without observation data
Raw observation files (.obs, .rnx, .crx) tracking satellite signal metrics over time rather than broadcast orbital ephemeris.
Non-standard proprietary binary formats without receiver decoding specifications
Standard RINEX observation format files, or supported multi-vendor raw binary logs.
Common questions
What is GNSS data analysis and why is it important?
GNSS data analysis audits raw satellite observations to evaluate signal quality, tracking continuity, multipath contamination, and cycle slip frequency. Analyzing data prior to positioning prevents erroneous coordinate calculations, saves field re-survey costs, and guarantees geodetic compliance.
How do I perform GNSS data analysis online without software install?
Upload your RINEX 2/3/4 file (or raw receiver log) to PosFlow (https://posflow.ai/gnss-data-analysis). The platform automatically audits observation metrics across GPS, GLONASS, Galileo, BeiDou, and QZSS, delivering an instant quality verdict, visual elevation plots, and a 0-100 health score.
What causes poor scores in GNSS data analysis?
Low GNSS quality scores typically stem from physical obstructions causing severe multipath, electromagnetic interference causing low SNR, high receiver dynamics triggering cycle slips, or aggressive tracking elevation cutoffs creating missing epochs.
Does PosFlow support batch GNSS data analysis?
Yes. Survey teams, CORS operators, and monitoring engineers can analyze hundreds of station files simultaneously through the PosFlow web interface or automate continuous audits using the REST API (https://posflow.ai/docs/api).
Related technical guides
Standards & Specifications
A free account covers files up to 100 MB. No card required. View plans and usage costs
Run full GNSS data analysis