GNSS observations: pseudorange, carrier phase and Doppler
Understand what GNSS receivers measure, why carrier phase needs ambiguity resolution, and which raw observations to keep for PPP, PPK and quality checks.
GNSS Knowledge & News
Understand GNSS.
Process with confidence.
Practical guides to GNSS observations, standards, file formats, quality analysis, precise positioning and coordinate systems.
GNSS technology
Standards & interoperability
RINEX 2 vs 3 vs 4: choosing a compatible GNSS format
Compare RINEX observation codes, navigation records and compression. Choose a version your processor supports without silently dropping GNSS signals.
Data formats
GNSS files explained: RINEX, SP3, CLK, ANTEX and RTCM
Identify GNSS observation, navigation, orbit, clock and antenna files. Learn which files belong together before a quality check or precise positioning run.
How to Convert u-blox UBX Raw Data to RINEX 3: Practical Guide for Surveyors
A practical engineering guide to converting u-blox ZED-F9P and NEO-M8T raw binary .ubx files into clean RINEX 3.04 observations for RTK, PPK, and PPP.
Quality analysis
CORS Station Continuous Quality Monitoring: A Migration Guide from Legacy TEQC
Migrate CORS network quality control from unmaintained TEQC to modern multi-GNSS pipelines. Track cycle slips, multipath and completeness across BDS-3, Galileo and GPS.
How to read a RINEX quality report: gaps, slips, multipath and SNR
A practical RINEX quality checklist for epoch gaps, carrier-phase cycle slips, multipath and signal strength, with a worked completeness example.
How a RINEX quality score is calculated
The thresholds and weights PosFlow grades observation files against — completeness, multipath, cycle slips, signal strength — and what each one is actually telling you.
TEQC is unmaintained. What to use instead
TEQC development has ended and it does not support RINEX 3. Compare replacement workflows by supported signals, quality metrics and preservation of observations.
Precise positioning
UAV Drone PPK Photogrammetry: End-to-End GNSS Workflow from Raw Log to Camera Geotag
Master the complete UAV PPK workflow: converting raw receiver logs, quality-checking base and rover data, solving kinematic baselines, and applying antenna lever arms.
PPP not converging? Check observations, products, antennas and frames
Troubleshoot a PPP solution that will not converge. Check phase continuity, precise products, antenna metadata and reference frames before extending the run.
PPP vs PPK vs RTK: Complete Comparison for Precision GNSS Positioning
A technical guide comparing Precise Point Positioning (PPP), Post-Processed Kinematic (PPK), and Real-Time Kinematic (RTK): baseline limits, convergence, accuracy, and use cases.
Coordinate systems
Coordinate conversion vs transformation: CRS, datum, frame and epoch
Avoid coordinate mistakes involving EPSG codes, latitude/longitude order, ECEF, height and coordinate epoch. A checklist for traceable GNSS transformations.
CGCS2000 to WGS84: Reference Ellipsoids, Epochs, and Transformation Parameters
Technical explanation of the relationship between China Geodetic Coordinate System 2000 (CGCS2000) and WGS84: reference frames, plate motion, and 3D Helmert transformation.
Product Release
Unified Jobs, multi-GNSS PPP, and Windows-native conversion
One Jobs page now tracks every conversion, quality check, and processing task. Apex delivers automated static and kinematic PPP processing, and a Windows worker adds native Trimble, Topcon and Leica raw-log conversion.
Unified JobsApex PPPWindows worker
June 29, 2026
What's New
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One Jobs page across all four products✓
Automated cloud PPP processing✓
Windows worker: Trimble, Topcon, Leica logs✓
Product-named storage for Crux and Flux✓
Live job status over WebSocketProduct Update
Flux adds NovAtel plus containerised Septentrio, Javad and u-blox converters
sbf2rin, jps2rin and ubx2rinex now run in isolated containers, and NovAtel OEM logs convert natively alongside the existing vendor formats.
July 3, 2026
Product Update
Jobs: batch delete, retry, restart and convert-again
Failed conversions can be retried in place, finished jobs re-run with new settings, and old entries cleared in bulk from the Jobs page.
July 1, 2026
Release
Pricing plans and pay-per-use credits go live
Free, Pro and Business tiers are now available, with pay-per-use credits for burst processing beyond your monthly job allowance.
June 30, 2026
Product Update
Axis redesign: CRS cards with single-point and batch tabs
Pick source and target CRS from presets or any EPSG code, swap them in one click, and transform whole coordinate files in batch.
June 29, 2026
Product Update
Cancel in-progress jobs from the Jobs page
Long-running QC and processing tasks can now be cancelled directly from the job list or the job detail view.
June 26, 2026
Release
PosFlow brand and workspace redesign
A new design system with dark and light themes, and a workspace reorganised around the surveying pipeline: data, quality, processing, delivery.
June 24, 2026