What’s the accuracy of GNSS fixes by DEBUT devices?

Two terms are mentioned when talking about GNSS accuracy.

• DOP (Dilution of Precision), a value to describe the effect of geometry of used satellites on GNSS positional measurement precision. According to past researches, it is an effective way to screen GNSS data or can be set to improve GNSS accuracy.
• CEP (Circular Error Probable), which is defined as the radius of a circle, centered on the actual location, whose perimeter is expected to include 50% of the GNSS fixes.

1. For DOP, you can download GNSS data from Ecotopia data center and refer to HDOP (Horizontal Dilution of Precision) and VDOP (Vertical Dilution of Precision) field of a certain piece of GNSS data.
   Note: Some older devices, such as FLEX and some models of LEGO, do not use HDOP and VDOP to indicate the GNSS accuracy. For those devices, you can refer to HorAccuracy and VerAccuracy in the downloaded GNSS data file.

2. For CEP, both chip test data by chip manufacturer and device test data by us are offered below for your reference.

   • Chip Test Data by chip manufacturer
     Prerequisite:
     • GNSS signal strength is over -130 dBm
     • Number of connected satellites is more than 6
     • Chip works at the frequency of 1 GNSS fixes per second for 24 hours in static state
       

   Test result: - Horizontal positioning accuracy: CEP (50%) 2.5 m, meaning that 50% of the GNSS fixes falls within a circle with a radius of 2.5 m - Vertical position accuracy: not provided. According to past researches, on average the vertical or altitude error is 1.5 to 3 times greater than the horizontal error.

   • Device Test by us
     We have been doing device test on GNSS accuracy in various environments. Below are 2 examples:
     For devices somewhere in downtown area of Chengdu, China, the accuracy is from 50% within 5m to 85% within 10m.
     For devices somewhere in Sanjiang Plain, China, the accuracy is from 85% within 5m to 98% within 10m.

The above mentioned testing was done in an ideal environment. In actual use of the device, there are many factors that can impact GNSS accuracy. For more information, see Why does one obvious GNSS error occurs sometimes?