GO Telematics Device GPS Precision Summary
Support Document
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Learn more about how a GO telematics device obtains latitude, longitude, altitude, and speed coordinates directly from the applicable GPS chipset (“GPS Chipset”) embedded in the GO telematics device.
GO® Telematics Device GNSS Precision Summary
How the GO Telematics Device Evaluates GNSS Coordinates
A GO telematics device obtains latitude, longitude, altitude, and speed coordinates (“GNSS Coordinates”) directly from the applicable GNSS chipset (“GNSS Chipset”) embedded in the GO telematics device. In order for GNSS Coordinates to be considered valid by Geotab, the following conditions must apply:
- A latitude, longitude, and altitude (commonly referred to as “3D” in GNSS terminology) fix using at least four (4) satellites.
- A GO telematics device requires a minimum of four (4) satellites to be tracked by the GO telematics device for a GNSS record to be valid.
- A GNSS record containing the GNSS Coordinates is marked by Geotab as not valid if it does not meet this requirement.
- The Position Dilution of Precision (PDOP) needs to be six (6) or less.
- This PDOP threshold is programmed into the GNSS Chipset by Geotab. A lower PDOP value indicates a more accurate GNSS reading (i.e. a PDOP of 1 would be considered a more accurate GNSS reading than a PDOP of 2, etc.)
- A GNSS record containing the GNSS Coordinates is marked by Geotab as not valid if it does not meet this requirement.
- The time dilution of precision (TDOP) needs to be ten (10) or less.
- TDOP relates to the synchronization between the GNSS Chipset receiver’s time and the satellite time. This threshold is programmed into the GNSS Chipset by Geotab.
- A GNSS record containing the GNSS Coordinates is marked by Geotab as not valid if it does not meet this requirement.
- The Position Accuracy Estimate needs to be within thirty (30) meters.
- The position accuracy estimate threshold is programmed into the GNSS Chipset by Geotab.
- A GNSS record containing the GNSS Coordinates is marked by Geotab as not valid if it does not meet this requirement
- The Speed Accuracy Estimate needs to be within one (1) meter per second (m/s).
- The GNSS Chipset sends an estimate of the speed accuracy; contained in the GNSS Coordinates.
- A GNSS record containing the GNSS Coordinates is marked as not valid by Geotab if it does not meet this requirement.
- GNSS Coordinates must not have a speed increase of over 30 km/h (18.64 mph) from the previous GNSS Coordinates.
- A GNSS record containing the GNSS Coordinates is marked as not valid by Geotab if it does not meet this requirement.
Chipset Specification — Circular Error Probable (CEP) Accuracy
GO9 (Hardware version E1 or higher) / GO9B (all versions) | GO9 (Hardware version D3 or lower) |
1.5 meters with SBAS(1)(3) | 2.5 meters with SBAS(3) |
Chipset Specification — Tracking Sensitivity
GO9 (Hardware version E1 or higher) / GO9B (all versions) | GO9 (Hardware version D3 or lower) |
-167dBm(2) | -167dBm(2) |
Chipset Specification — Acquisition Sensitivity
GO9 (Hardware version E1 or higher) / GO9B (all versions) | GO9 (Hardware version D3 or lower) |
-148dBm(2) | -148dBm(2) |
Note:
- SBAS (Satellite-based augmentation system) are region-specific satellite constellations that transmit data used to correct errors in GNSS signals
- GPS + GLONASS + Galileo + Beidou
- Chipset specification is not guaranteed to be reflected accurately in real-world scenarios, due to various external factors such as the installation location of the GO device. In particular, the first few GNSS positions at the beginning of the trip may experience suboptimal accuracy. Geotab tries to overcome any imperfections in GNSS performance via post-processing in MyGeotab to deliver a seamless user experience.
