Common GPS & Tracking Issues

Overview

One of the most common problems that occur with any GPS is correct tracking. The most up-to-date navigation services - think Google Maps- have the ability to pinpoint your location with a minimum fault of 3-10 meters. This positioning works best in ideal conditions, meaning you are located in a city, preferably a major one, are outdoors compared to indoors and have a strong cellular connection with whichever device you are using. Yet even with ideal conditions met, there are some points during the day that you will experience points with poor tracking. Unfortunately, this is something you do not have the ability to change. So, what causes a sudden change in accuracy when the tracking application was working correctly 30 minutes ago? In short, it is often about GPS signals. 

GPS signals have to travel huge distances through the atmosphere from multiple satellites to reach your mobile phone (in most cases they do it via special devices) and the quality of such signal plays a major role. The problem is that your device needs to receive strong signals from at least 3-4 satellites, and ideally 7-8, at a time to provide the most accurate location data. This is why it is best to be outdoors if you desire the best signal possible. This way your device won’t meet as many barriers on its way and it will have an opportunity to receive the closest and strongest signal. In addition, both urban and natural canyons (large buildings in cities, trees, mountains, ridges, etc.) can affect any GPS signal. If a satellite is not directly overhead in these locations, it becomes much harder to track accurately and reduces the GPS signal accuracy. In other words, the more open sky view you can get, the more accurate signal you will receive. 

The most common method to track with GPS is with a cellphone or other LTE/4G enabled device (i.e iPad or Android Tablet). By using cellphone towers and base stations and the distances between these “anchors”, these devices can be tracked with relatively good accuracy. As you travel, you move from one cell zone to another. Base stations monitor the strength of your phone’s signal and as you move toward the edge of one cell, your signal strength diminishes. At the same time, the base station in the cell you are approaching notices the strength of your signal increasing. As you move from cell to cell, the towers transfer your signal from one to the next and the distances between the receivers essentially determine your position. While this is a simple and effective method for GPS tracking, this process also has its drawbacks. In remote locations, towers may be so far apart that they can’t provide consistent signals, thus leading to inaccurate positioning. Even when towers are plentiful – in major cities or population-dense areas, challenging topography and tall buildings or thick layers of concrete can interrupt signals. Since obstacles like trees and buildings can affect how long it takes your signal to travel to a tower, this method is often less accurate than a dedicated GPS device. 

Even without a proper GPS receiver, cell phones and tablets can provide good information about your location. Mapping software uses this information to determine your location based on measurements of your signal: Other problems, some common and others rare, can affect the ability of any device to obtain good positioning data include:

Cold starts

When a GPS is turned on or if the GPS has been inactive in the background for too long, the GPS needs to download data from the satellites that describes the position and timing of all of the satellites in the system. This can take up to five or more minutes to be corrected and can cause incorrect GPS tracking. This will sometimes appear to make the track jump. 

Not enough satellites

Many GPS devices ideally need to receive signals from at least 7 or 8 satellites to calculate location to within an accuracy of ~10 meters. With fewer satellites the amount of uncertainty and inaccuracy increases. With less than 4 satellites, many GPS receivers struggle to produce accurate location estimates and will report “GPS signal lost” at points during the route.

Poor Hardware

If your device is older, damaged or has poor GPS reception capabilities it will struggle to receive satellite or cellphone tower signals.

Low Battery on GPS devices

A low battery can affect the proper functioning of the GPS on any device.

Multipath signals

When signals from GPS satellites or cellphone towers bounce off buildings, the GPS receiver can be confused by the extra time the signal took to reach it. In these cases, you may observe sudden errors in position. There is not much that can be done in these circumstances to reduce the effects of multipath errors. GPS is simply less accurate in these situations.

GPS Drift

The GPS track deviates from the road. You may see that the route generally follows the shape of the road but with much less precision.

Lost GPS signal

If a signal is lost and sometime later re-acquired the pre- and post-signal-loss points will be treated just like any other two points (although more time has elapsed between them) and connect them with a straight line. 

GPS bounce

A ‘jumpy’ GPS track can cause your activity to report more distance than you actually travelled since each ‘zig’ and ‘zag’ of your GPS track has to be accounted for with a straight line connecting them.

Radio interference or jamming

Satellite maintenance/maneuvers can affect GPS signals creating temporary gaps in coverage. In some cases, a device’s GPS hardware is working fine, but the software being used is faulty. For example, users can be misled by GPS software services including:

• Incorrectly drawn maps
• Mislabeled businesses and other points of interest
• Missing roads, buildings, communities, etc.
• Incorrectly estimated street addresses

How to Improve your GPS Accuracy?

So now that you understand that GPS is dependent on various aspects, here are some suggestions that will allow you to get the most precise location data on a specific device: 

1. Position your device in such a way as to capture the GPS signal.
2. Keep the device high and in open areas - near windows if you are in a car or building – to get the best outcome. 
3. Avoid places with high probabilities of poor GPS reception to the best of your ability (natural or city-created valleys and canyons, dense forests, walls, etc.) 
4. Keep your device charged while running GPS applications. Low battery levels are one of the main reasons for losing signals on your device:
5. Keep the GPS application active on your device. When an application becomes stagnant from non-use it often stops actively tracking.
6. Research what is best for your device. Different devices have different GPS chips. If GPS is one of the vital tools you will need then be sure to pick a device that is accommodating.
7. Consider connecting to third-party Bluetooth GPS receivers for better signals. This will improve your positioning data notably.
8. There is always the option to restart your device and/or turn GPS on/off several times. This helps more often than not. The reboot helps the GPS system to recalibrate, which can lead to better signal reception.