GNSS Correction Sources

Kevin Grover
2025-11-28T18:53:31Z

This guide outlines the best practices for leveraging GNSS base stations within the Looq AI PPK workflow. This document is designed to help understand the available correction methods and how to achieve the highest possible data accuracy.

Quick Summary: The Looq PPK Workflow

Looq technology utilizes a PPK (Post-Processed Kinematic) workflow. Unlike Real-Time Kinematic (RTK), which requires a constant connection between base and rover, PPK processes the data after the capture is complete.

How it works: The Looq platform compares the "noisy" GPS data from the device with "known" static data from a base station. By calculating the difference between where the base station thought it was vs. where it actually is, the system corrects the Looq device's flight path with centimeter-level precision.

The Golden Rule: The base station must be recording data for the entire duration of the Looq capture, plus a buffer before and after.

Overview of Correction Sources

There are three main ways to provide base station data for Looq processing.

Correction Source | Type | Best Used For... | Pros & Cons

Looq Auto Base

Free (Public)

Projects in urban/semi-urban areas with good government infrastructure (e.g., NOAA CORS in the US).

Pros: Free, no extra hardware needed.

Cons: Stations can be far away (long baseline), lowering accuracy. Data availability may lag by 24hrs.

Paid Providers

(Rinex)

Subscription (Trimble VRS, Leica SmartNet)

Projects needing guaranteed uptime and density in areas without free Looq Auto processing coverage.

Pros: High density of stations (short baselines), reliable uptime.

Cons: Costly subscription fees; requires downloading RINEX from their portal.

Local Base Station

(Rinex)

Hardware (Your own receiver)

Remote sites, consistent accuracy for survey projects, fastest processing workflow with Looq

Pros: Highest accuracy (shortest baseline); total control over data. Fastest processing workflow with Looq as corrections are available immediate after capture

Cons: Requires extra equipment setup; risk of operator error (e.g., moving the tripod).

Critical Requirements for Looq Processing

Regardless of the source, the RINEX file uploaded to the Looq platform must meet these strict criteria to process correctly:

File Format: Must be a RINEX observation file (extensions: .obs, .XXo like .23o). Uploaded as a ZIP file to the Looq web portal.

Minimum Duration: The base file must cover the entire flight plus a buffer.

Rule of Thumb: Start the base 10 minutes before the capture and leave it running for 10 minutes after.

Looq Specific: The base data usually needs to span at least 1 hour total to ensure robust convergence, even if the flight is short.

Sampling Rate: 1 Hz (1 second) is the gold standard.

Note: Some CORS stations record at 30s intervals. This is often too slow for high-accuracy drone/handheld corrections. Always check the station's interval before heading to the field.

Which do I use?

It is up to you to use which correction source best fits your projects needs.

When you need a fast capture for a project that doesn't require accurate absolute positioning of your data, then the Looq AUTO base option is a good choice.

When the highest accuracy is needed on projects or you want more control over the GNSS processing steps with Looq, then using your own Local base option is a great choice.