> ## Documentation Index > Fetch the complete documentation index at: https://docs.shieldgps.com/llms.txt > Use this file to discover all available pages before exploring further. # GPS Accuracy and Network Coverage for ShieldGPS Devices > Learn how accurate ShieldGPS tracking is, what affects location precision, and how cellular network coverage works for your device. ShieldGPS devices use advanced GPS technology combined with 4G LTE mobile networks to deliver location accuracy to within a few metres under normal conditions. Understanding what affects accuracy and coverage helps you get the best performance from your tracker and interpret the positions shown in the app. ## GPS Accuracy ### Typical accuracy In open-sky conditions — outdoors with a clear, unobstructed view of the sky — your ShieldGPS tracker reports your location to within a few metres. Location updates are delivered every 10 seconds, so the map view in the app and web dashboard stays current in near real time. ### What affects accuracy Several environmental factors can reduce the precision of your tracker's reported position: * **Tall buildings and urban canyons** — dense city-centre streets can reflect and block GPS signals, causing the reported position to shift by tens of metres. * **Tunnels and underground areas** — GPS signals cannot penetrate underground. While in a tunnel, the tracker relies on the last known position until it re-emerges. * **Underground car parks** — concrete and steel construction blocks both GPS and cellular signals. The tracker will resume accurate reporting once the vehicle returns to street level. * **Dense tree cover** — thick forest canopy can degrade signal quality, particularly in wet conditions. * **Metal-roofed enclosures** — storing a tracker inside a metal shed, container, or vehicle boot can reduce or block GPS reception entirely. ### Map pin offset The location shown on the map always reflects the device's most recent GPS fix. If the tracker has been stationary indoors or in a covered area, the map pin may appear slightly offset from the vehicle's actual position. Once the device moves back into open-sky conditions, the pin will update to the correct location within a few seconds. ## Network Coverage ### 4G LTE mobile networks ShieldGPS devices transmit location data over 4G LTE mobile networks. Coverage quality depends on the local network infrastructure in the area where your tracker is located. In well-served urban and suburban areas, connectivity is continuous. In rural, mountainous, or very remote locations, coverage may be intermittent or unavailable. ### Built-in SIM card — no setup required Every ShieldGPS device ships with a built-in roaming SIM card managed entirely by ShieldGPS. You do not need to source, insert, or configure a SIM yourself — the device is ready to connect to the network once it is powered on and your subscription is active. ShieldGPS devices come with a built-in SIM card. You cannot use your own SIM card in ShieldGPS devices — the hardware does not support third-party SIMs. ## Tips for Improving Accuracy Mount your tracker where it has the clearest possible view of the sky. Behind the windscreen — rather than in the boot, under the chassis, or inside a metal compartment — gives the GPS antenna the best line of sight to satellites and produces the most accurate readings. After powering on a device for the first time, or after a long period without power, allow a few minutes for the tracker to acquire its initial GPS fix. This is normal behaviour. Once the first fix is obtained, subsequent updates are near-instant. ## Need More Help? If you are consistently seeing inaccurate positions or your tracker is not reporting location at all, visit the [Tracker Offline](/faq/tracker-offline) or [Location Not Showing](/faq/location-not-showing) guides for further troubleshooting steps. You can also email [support@shieldgps.co](mailto:support@shieldgps.co) with your IMEI number for personalised assistance.