Selecting a mobile device

A common question that I encounter is “What device do you recommend that I use for my ArcPad or mobile GIS application?” Unfortunately, the most straight forward answer is “It all depends!” Choosing a suitable device for your mobile GIS application and field tasks is not unlike choosing which pair of shoes to wear – it is all a matter of trade-offs. Hiking boots are great when comfort and ruggedness are the most important requirements, but are not really suitable for attending a wedding! There is simply no pair of shoes that is suitable for all the varied activities that we participate in. So it is with choosing a suitable mobile device.

There are many factors which need to be considered when choosing a mobile device. Some of these factors are: price, size, screen, weight, ruggedness, battery life, integrated GPS/camera/rangefinder/compass, and operating system. Many of these factors are mutually exclusive, for example with current technology (that is readily available and affordable!) it is not possible to have a device that is small enough to fit in a shirt pocket and at the same time has a large, laptop-size screen. It is all a matter of trade-offs – choosing which factors are most important and deciding which factors are “nice to have”.

For some mobile applications GPS accuracy is the most important factor. For example, your application might require sub-meter accuracy. This automatically eliminates all but a few GPS receivers available today, and narrows the choice to professional-grade GPS receivers. Your next requirement might be for a cable-free, integrated mobile device and GPS receiver. This reduces the choice to less than a handful of devices, specifically integrated handheld and GPS devices from Magellan (formerly Thales), Topcon, and Trimble.

GPS is just one of the factors that could be the determining factor for selecting a mobile device. There are many other determining factors. Two useful factors to consider are the application needs and the means of transport.

Application Needs
Different mobile GIS applications, and their related tasks, have different requirements for an appropriate mobile device.

Application Needs	Mobile Device Characteristics
	Weight	Size	Battery Life	Operating System
Smaller Screen	Lighter	Smaller	Longer	Windows Mobile Windows CE
Larger Screen	Heavier	Larger	Shorter	Windows XP

Consider for example a fire hydrant inspection application for a city. When the person is inspecting the fire hydrant in the field the only geographic information that is of interest is the fire hydrant, and possibly a small geographic area immediately surrounding the particular fire hydrant. For this application, a small screen is suitable and useful. Once it has been decided that a small screen is suitable for our fire hydrant inspection application it automatically follows that a lighter and smaller mobile device is appropriate. These smaller, lighter devices typically run Windows Mobile (or Windows CE) and have much longer battery life.

In contrast, consider a field supervisor for the roads department of a large city. For this field application the person needs to view a large amount of detail for a large area. A small screen for this application is not suitable, since it is not possible to display a lot of detail for a large geographic area on a small screen. The application requirement for a large screen automatically leads to the requirement for a larger, heavier device – such as a laptop or Tablet PC. These larger devices typically have shorter batter life, and run Windows XP (or Windows 2000).

Means of Transport
Another approach to follow when determining a suitable mobile device is to consider the means of transport.

Means of Transport	Mobile Device Characteristics
	Screen Size	Weight	Size	Battery Life	Operating System
Vehicle-based	Larger	Less Important	Less Important	Less Important	Windows XP
Foot-based	Smaller	Lighter	Smaller	All day	Windows Mobile Windows CE

If the field application involves spending a small amount of time outside of a vehicle then the size, weight, and battery life of the mobile device is less important since you do not need to carry the device for very long, and the vehicle can provide “unlimited” amount of power to the device. For this situation a laptop or Tablet PC running Windows XP is a good choice.

However, if the field application involves spending many hours walking, away from a vehicle, then the size, weight, and battery life of the mobile device is very important. For this situation a smaller and lighter handheld device running Windows Mobile (or Windows CE) is a good choice. These devices also typically have sufficient battery capacity to use the device for a full day’s work without needing to charge or change the battery.

Summary
Each mobile application is different, with unique requirements. As a result, it is unlikely that there will ever be a perfect device which is suitable for all mobile applications. Choosing a suitable mobile device involves identifying the factors which are essential for the mobile application, and focusing on these selected factors. Placing less emphasis on the “nice to have” factors makes choosing a mobile device much easier!