ISO 17123-11:2025

Overview

ISO 17123-11:2025 - "Optics and optical instruments - Field procedures for testing geodetic and surveying instruments - Part 11: GNSS instruments" - defines a practical, field-based verification procedure to confirm that a GNSS-based measuring system and its measurement procedure meet a required measurement uncertainty at a given location and time. The standard compares three-dimensional GNSS coordinates to established reference coordinates, is independent of receiver hardware, satellite data streams and correction services, and is designed for routine on‑site checks with limited economic impact.

Key topics and requirements

• Objective: Verify that GNSS-derived 3D coordinates meet a specified measurement uncertainty for the task and environment.
• Test principle: Compare measured coordinates (E, N, H) against reference coordinates under operating field conditions.
• Delimitation criteria: Quantitative (measurement uncertainty classes) and qualitative rules to adapt the procedure to diverse instruments and applications.
• Multistage test procedure:
  • Stage 1 - Simplified test: Quick checks suitable for routine verification.
  • Stage 2 - Full test: Comprehensive field procedure with detailed calculation and interpretation.
  • Stage 3 - Extended test: Advanced diagnostics (e.g., antenna isotropy or antenna property tests, antenna diagnostics).
• Influencing factors: The procedure explicitly includes main parameters affecting coordinate determination to reflect real-world performance.
• Supporting material (informative annexes): Examples of test procedures and results, long-term static GNSS reference establishment, antenna diagnostics, and mapping of applications to measurement uncertainty classes.
• Independence: Applicable regardless of GNSS technology, instrument morphology, correction data or data streams.

Applications

ISO 17123-11:2025 is applicable to any GNSS‑based geodetic or surveying application where verification of positional accuracy and measurement uncertainty is required, including:

• Site acceptance and daily performance checks for survey crews
• Quality assurance for cadastral, construction and engineering surveys
• Verification for geodetic control points and monitoring installations
• Pre‑task checks for mapping, asset management, and infrastructure projects

Who should use this standard

• Surveyors and geodetic engineers performing in‑field GNSS measurements
• QA/QC managers in surveying and construction firms
• Equipment manufacturers and calibration service providers
• Geospatial program managers establishing measurement‑accuracy procedures

Related standards

• ISO 17123 series (field procedures for geodetic instruments)
• ISO 17123-1 (Theory)
• ISO 17123-8 (GNSS test procedures for RTK applications)
• ISO 9849 (Vocabulary for geodetic and surveying instruments)

Keywords: ISO 17123-11:2025, GNSS instruments, field procedures, measurement uncertainty, geodetic surveying, reference coordinates, antenna diagnostics, test stages.