GPS Tracker Not Accurate: Why Your Positions Are Wrong or Jumping

A GPS tracker that places a vehicle in the wrong street, or shows it jumping between two locations it never visited, is more than an annoyance. It erodes confidence in the data and makes the platform difficult to trust. Here is what causes inaccurate GPS positions and how to address it.

Cold start: the most common cause of initial inaccuracy

When a GPS device has been powered off or has not had a satellite fix for an extended period, it needs time to reacquire satellites when it powers back on. During this period, the position shown is unreliable and may be way off.

A cold start can take anywhere from 30 seconds to several minutes depending on the device and conditions. A warm start, where the device has been off for a short time, is much faster.

If you see a vehicle appearing in a completely wrong location when it first sets off in the morning, cold start is almost certainly the explanation. The position will correct itself within a few minutes once the device has a solid satellite fix.

Urban canyon and signal multipath

In dense city environments, GPS signals bounce off the faces of tall buildings before reaching the receiver. The device receives a signal, but the reflected path is longer than the direct path, so it calculates a position that is off by tens to hundreds of metres.

This is called multipath interference and it is a fundamental limitation of GPS in urban areas. It cannot be fully eliminated, but some devices handle it better than others through filtering and signal processing.

For fleet tracking purposes, positions in urban canyons should be understood as approximate. If precise kerb-level accuracy matters, other technologies such as WiFi positioning or HD maps can supplement GPS.

Polling interval too low

If a tracker reports its position every 10 minutes, the platform draws a straight line between those two points on the map. The vehicle may have taken a completely different route in between, made multiple stops, or turned around.

This creates positions that look wrong or routes that appear to jump. The fix is straightforward: increase the reporting frequency. For accurate route replay and real-time visibility, a report interval of 30 seconds to two minutes is appropriate.

Higher reporting frequency increases data usage, so confirm your SIM plan can handle it across all devices in the fleet.

Antenna issue

A GPS antenna that is not properly connected, positioned incorrectly, or physically damaged will give a weaker satellite signal, resulting in fewer satellites locked and a less accurate fix.

The antenna should have a clear, unobstructed view of the sky. Mounting under metal panels, beneath seats, or inside the boot significantly degrades signal quality.

Check that:

• The antenna connector is fully seated.
• The antenna is positioned facing upward or as close to it as possible.
• There is no metallic material directly above the antenna.

For devices with internal antennas, the tracker itself needs to be mounted in a position where it has some sky visibility, not buried deep in the dashboard or boot lining.

Poor satellite count or low HDOP

GPS accuracy depends on how many satellites the device can see and how they are distributed across the sky. The HDOP (Horizontal Dilution of Precision) value tells you the geometric quality of the satellite arrangement. A lower HDOP is better; values above four are associated with significantly reduced accuracy.

Some device configuration tools show the current satellite count and HDOP. If you consistently see low satellite counts (below four or five), the antenna placement or environment is the issue.

Step-by-step fix sequence

1. Check when the inaccuracy occurs. Is it only at startup? That is a cold start issue.
2. Is the vehicle in a dense urban area? Expect reduced accuracy and treat positions as approximate.
3. Review the report interval. If it is set above two minutes, tighten it for better route accuracy.
4. Check antenna placement and connector seating.
5. Review HDOP and satellite count in the device configuration if accessible.
6. If the device consistently shows poor accuracy across all conditions, consider a device with a better antenna or a different mounting position.

How Traknova handles GPS accuracy

Traknova’s GPS tracking platform uses data from a range of hardware with different antenna configurations. Our team can advise on installation best practice and reporting intervals for your specific devices.

Book a demo to see how fleet positions display in the platform and understand how accuracy is managed at scale.