1. Introduction
Global Navigation Satellite Systems (GNSS) are the backbone of modern geospatial and civil engineering projects, enabling high-accuracy positioning across a range of environments. Surveying with GNSS, particularly when using differential methods like RTK or PPK, requires a well-defined workflow to ensure precision, repeatability, and compliance with industry standards. This guide outlines the practical steps involved in conducting a GNSS-based survey, from field preparation to data processing.
2. Pre-Survey Preparations
Before beginning the survey, several technical and logistical elements must be addressed:
2.1 Equipment Checklist
- GNSS receiver (rover) and controller
- Base station (if RTK/PPK is used)
- Batteries and chargers
- Tripod or pole with fixed height
- Radio or cellular modem (for RTK)
- Data collection software or field logger
- Personal protective equipment (PPE) and site map
2.2 Project Planning
- Define survey objectives (e.g., topographic mapping, control point establishment).
- Select appropriate coordinate system and projection.
- Identify control points, benchmarks, or required baselines.
3. Setting Up the GNSS System
3.1 Base Station Setup (RTK/PPK)
- Place the base station over a known point (or mark and later georeference).
- Center the base using an optical or laser plummet.
- Level the tripod and fix the base station to it securely.
- Set up communication (radio or NTRIP) if using RTK.
3.2 Rover Initialization
- Power on the rover and connect to the controller.
- Load the project file, coordinate system, and point codes.
- Establish link with the base (for RTK) and confirm correction signal reception.
4. Field Data Collection Procedure
4.1 Static Survey (Control Network, PPK Baseline)
- Place the receiver over each point and maintain occupation for 15–60 minutes depending on the required precision and baseline length.
- Log raw data files for post-processing.
- Minimize multipath by avoiding metallic structures, trees, or buildings.
4.2 Kinematic Survey (RTK/PPK Rover Survey)
- Move from point to point while maintaining satellite visibility.
- Wait for a fixed RTK solution (indicated by the controller) before storing each observation.
- Hold the pole vertically and consistently use the correct antenna height.
- Record multiple epochs at each point (typically 5–10 seconds) for redundancy.
4.3 Stakeout Survey
- Upload design coordinates into the controller.
- Navigate to the target point using the directional guidance.
- Mark the point on the ground and record any offset or deviation.
5. Quality Control and Checks
- Monitor Dilution of Precision (DOP) values; ensure they remain below acceptable thresholds (e.g., PDOP < 3).
- Cross-check new GNSS points with existing control points if available.
- Perform a “close-out” check by reoccupying the first station at the end of the survey.
- Log metadata such as weather conditions, satellite status, and field notes.
6. Post-Survey Data Management
6.1 RTK Surveys
- Export field points with coordinates, codes, and descriptions.
- Import into CAD, GIS, or civil engineering software for mapping and analysis.
6.2 PPK Surveys
- Download raw data from both base and rover.
- Use GNSS post-processing software (e.g., Trimble Business Center, Leica Infinity, RTKLIB) to compute corrected coordinates.
- Apply corrections and validate accuracy using residuals and quality metrics.
7. Documentation and Reporting
- Prepare survey report including:
- Methodology and instrument specifications
- Summary of GNSS settings and configurations
- Base station coordinates and logs
- Point tables with coordinates and descriptions
- Include visual documentation (site photos, sketch maps, and screenshots from software)
8. Conclusion
Working with GNSS for surveying involves much more than just turning on a receiver. It requires a systematic approach to planning, equipment setup, data acquisition, and processing. Adhering to structured field procedures ensures data quality, project reliability, and professional accountability. Whether for boundary surveys, infrastructure development, or geodetic control, GNSS surveying continues to redefine the standards of spatial accuracy and efficiency.
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