4.8 Positioning Visual
Interactive diagram showing how satellite signals, base stations, and correction methods combine to produce survey-grade scanner accuracy.
How Corrections Reach the Scanner
Every GNSS correction method begins with the same source: satellites. The raw satellite signal alone is accurate to roughly 3 to 16 ft because the signal is distorted by the ionosphere, troposphere, and satellite clock drift. A receiver at a known location measures those distortions and produces correction data that cancels most of the error, bringing the result to 1.2 in RMSE or better.
GNSS Correction Signal Flow
Method Comparison
RTK via CORS / NTRIP
Why: You can connect to NTRIP. A CORS network covers the project area and you have cellular or Wi-Fi at the site.
Correction timing: Live, during the scan.
What you need: Mobile data or Wi-Fi. NTRIP credentials from your CORS provider (host, port, mountpoint, username, password).
What you skip: Any base station equipment. No post-processing.
Critical risk: A dropped NTRIP connection stops corrections immediately. That portion of the trajectory is not recoverable.
RTK via Your Own Base
Why: You are out of range of a CORS/NTRIP network but have internet at the site. You deploy your own base station at a known point.
Correction timing: Live, during the scan, delivered via NTRIP.
What you need: A multi-band GNSS receiver (such as an Emlid Reach RS3) at a known control point within 3.1 mi. In LixelGO, select Custom RTK type and enter the base NTRIP host, port, and mountpoint.
What you skip: Dependence on a third-party CORS network.
Critical risk: A wrong base coordinate shifts the entire scan by that exact amount. There is no warning and no way to correct afterward.
PPK (Post-Processed)
Why: No cellular or internet coverage at the site. You cannot receive NTRIP corrections in the field.
Correction timing: After the scan, in LixelStudio.
What you need: A base station (such as an Emlid Reach RS3) logging continuous RINEX data during the scan. The scanner raw GNSS log. LixelStudio PPK workflow. Base within 3.1 mi, under 1.2 mi optimal.
What you skip: Live internet in the field. No real-time fix confirmation.
Critical risk: A single gap in the RINEX file invalidates data for that period. Verify valid data points exceed 100 in LixelStudio before processing.
Legend and Key Specifications
Base station shown: The Emlid Reach RS3 is shown as an example of a commonly used third-party GNSS receiver. Any multi-band GNSS receiver that supports NTRIP output and RINEX logging will work in this role. The XGRIDS system does not require a specific base station brand.
Signal Paths
Equipment
Outputs
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