CORS Station Continuous Quality Monitoring: A Migration Guide from Legacy TEQC

Why legacy TEQC is an operational liability for modern CORS

Sources: UNAVCO: TEQC documentation and status · IGS: formats and standards

The blind spots of downgrading RINEX 3 to RINEX 2 for QC

Because TEQC does not parse RINEX 3 observation headers or multi-character signal identifiers, many network operators implemented pre-processing scripts that down-convert RINEX 3 files to RINEX 2.11. This practice silently discards tracking channels, collapses distinct tracking attributes into generic observable codes, and strips BeiDou-3 and modern Galileo signals entirely.

• Downgrading to RINEX 2 strips third-frequency and wideband signals (such as GPS L5, Galileo E5a/E5b, and BDS-3 B2a) critical for triple-frequency RTK and PPP.
• Tracking attribute nuances (such as pilot vs data channels or tracking modes) are lost, masking receiver firmware tracking discrepancies.
• A clean report from a downgraded file creates false confidence while multi-frequency interference remains undetected in the field.

Sources: IGS: formats and standards · UNAVCO: TEQC documentation and status

Core quality metrics for continuous reference station monitoring

Continuously operating reference stations require automated tracking of physical and radio-frequency characteristics across all active constellations. Daily observation sessions should be screened against four primary quality indicators:

• Observation completeness: Compare received epochs against expected epochs for each satellite system. Stations should maintain completeness rates above 95% above a 10-degree mask.
• Cycle-slip ratio: Track the frequency of loss-of-lock events per thousand epochs. High cycle-slip ratios indicate severe local multipath, low tracking SNR, or ionospheric scintillations.
• Multi-band multipath RMS (MP1, MP2, MP5): Compute linear code-minus-phase combinations across frequency bands. Elevated values highlight reflective clutter or antenna ground-plane degradation.
• Signal-to-noise ratio (SNR) versus elevation: Verify symmetric, bell-shaped signal gain profiles to confirm unobstructed horizons and proper antenna preamplifier gain.

Sources: ESA Navipedia: GNSS basic observables

Distinguishing environmental multipath from hardware degradation

When quality scores drop at a reference station, operators must distinguish temporary environmental changes from physical hardware degradation. Correlating tracking metrics across time and satellite azimuths isolates the root cause without premature antenna replacement.

• Seasonal foliage or new construction introduces azimuth-specific multipath increases and lower SNR at moderate elevation angles.
• Water ingress in antenna cables or connector oxidation manifests as a uniform, broadband SNR drop across all satellites and frequencies.
• Near-field reflections from newly installed metal railings or mast structures create pronounced cyclical oscillations in low-elevation multipath metrics.
• Receiver clock instabilities appear as simultaneous time-tag jumps or phase reset flags affecting all tracked constellations simultaneously.

Sources: ESA Navipedia: GNSS basic observables

Automating CORS quality control with REST APIs

Modern CORS operations manage dozens or hundreds of stations. Manually running desktop diagnostics or maintaining legacy shell scripts creates maintenance overhead. Cloud-native QC platforms provide automated pipelines that process hourly or daily sessions through programmatic endpoints.

• Configure receiver FTP push or pulling scripts to upload completed hourly or daily RINEX archives directly to cloud processing endpoints.
• Ingest structured JSON reports containing composite 0–100 quality scores, per-satellite statistics, and threshold flags.
• Trigger automated operational alerts when station quality drops below predefined thresholds (e.g. score < 75 or multipath RMS > 0.45 m).
• Archive long-term quality trends in network dashboards to monitor station stability and track antenna aging over multi-year baselines.

Sources: IGS: formats and standards

Step-by-step checklist for migrating off legacy TEQC

• Inventory station output formats: identify whether receivers produce native RINEX 3 or proprietary binary formats.
• Eliminate intermediate format downgrade steps: direct native RINEX 3.0x files directly into modern QC engines.
• Run dual-stack validation: execute legacy TEQC and modern QC concurrently on a benchmark dataset to calibrate baseline multipath thresholds.
• Establish multi-constellation monitoring rules: define pass/warning/fail criteria for BeiDou, Galileo, and GPS separately.
• Update downstream reporting: replace legacy TEQC compact summary scrapers with clean JSON API payloads.

Sources: UNAVCO: TEQC documentation and status

References and methodology

Technical definitions follow the sources below. Worked examples are illustrative; product-specific thresholds are identified as PosFlow settings. For corrections, contact PosFlow with the article URL and the relevant specification.

• IGS: formats and standards
• ESA Navipedia: GNSS basic observables
• UNAVCO: TEQC documentation and status

Put this into practice

• TEQC modern alternative
• RINEX quality checker
• PosFlow API documentation