Tech Chat | Understanding The Meaning & Accuracy of Common RTK Solutions

In daily GNSS RTK surveying, the RTK solution is an important indicator for positioning reliability and accuracy. Before beginning a survey, it's standard practice to confirm that the RTK solution has achieved Fixed status for centimeter-level accuracy. In this blog, we will introduce the meaning of each RTK solution and its typical accuracy, and how do they affect your results?

1. SINGLE: Single-Point Positioning

• Description: The SINGLE solution is the default status that typically appears when a GNSS receiver tracking satellites without receiving any corrections from a base station or CORS network. 
• Accuracy: Meter-level

2. DGNSS: Differential GNSS Positioning

• Description: In DGNSS solution, the receiver has started receiving corrections from a base station or a CORS network. However, due to factors such as environmental interference or suboptimal correction data quality, the position calculation remains coarse, though more refined than SINGLE mode. 
• Accuracy: Typically ranges from meter to sub-meter level

3. FLOAT: Float RTK Positioning

• Description: The FLOAT status occurs when the receiver is processing differential corrections but has not yet resolved the ambiguities to integer values, known as integer ambiguity resolution. In RTK positioning, resolving these ambiguities to integers significantly enhances accuracy. In FLOAT mode, however, ambiguities are still "floating" and have not reached this resolved integer state, resulting in reduced precision compared to FIXED mode.
  Normally, the float solution will change to fixed after the receiver calculating for a few seconds or moving to a better environment.
• Accuracy: Decimeter-level, better than DGNSS but less precise than FIXED

4. FIXED: Fixed RTK Positioning

• Description: The FIXED status represents the highest precision level in RTK positioning, where the GNSS receiver has achieved reliable ambiguity resolution with integer values. This solution provides robust positional accuracy, allowing surveyors to confidently carry out precise surveying.
• Accuracy: Centimeter-level, ready for professional surveying tasks
• Tips: When in FIXED, the differential age data is critical - ideally within 1-2 seconds for CORS/GSM mode or 2-5 seconds in radio mode.

Monitoring RTK Status & Differential Age in SingularPad Software

In SingularPad field surveying software, you can monitor the RTK status in the status bar. You can also notice an "age" parameter beneath the RTK status. This differential age represents the time elapsed since the last correction data was received, and it serves as an indicator of data freshness:

• 1-2 seconds: Ideal for CORS or GSM network corrections
• 2-5 seconds: Typical for radio-based corrections  

Maintaining a low differential age is crucial for reliable RTK positioning, particularly in FIXED mode, where high accuracy depends on stable, up-to-date correction data.

By understanding these RTK statuses—SINGLE, DGNSS, FLOAT, and FIXED—you can confidently assess when your GNSS receiver is ready for high-precision surveying tasks. Achieving FIXED mode offers the most reliable accuracy for detailed measurements, while the other statuses provide varying levels of precision. Familiarity with these statuses will empower you to use RTK technology more effectively and ensure accurate results for your surveying projects.

Learn more about SingularXYZ RTK receivers.

https://www.singularxyz.com/X1.html
https://www.singularxyz.com/Z1.html
https://www.singularxyz.com/Sfaira_ONE_Plus.html
https://www.singularxyz.com/P2_Plus.html