Feature: Usability of GPS Receivers in a Sporting Environment

Many people have an appetite for adventure, but most only go on hiking trips or treasure hunts in their imagination. It is interesting that technology now makes adventure and finding that big treasure more accessible to more people. Global Positioning System (GPS) technology has become increasingly accessible to the general public, with the result that many outdoor sports people now use GPS receivers (GPSr) for navigation in a host of activities, such as hiking and geocaching.

In spite of the growing popularity of GPS, there are many usability issues to be addressed. Outdoor sports like geocaching (a popular, high-tech sport of treasure hunting introduced to the public by GPS technology) involve getting out into nature where the user may encounter various obstacles and the GPSr must take all usage and behavioural aspects into account.

The use of handheld GPS receivers under hazardous conditions presents very specific usability problems that can lead to ineffective navigation and even compromise the user’s safety. We need to examine possible solutions to interaction problems in the use of GPS receiver in a sporting environment. Is it possible for a handheld GPS receiver to actively assist the user without distracting him or her from their main task?

A GPS receiver is basically a handheld computer that offers amazing functionality in a small package. Its small size, long battery life, positional accuracy and robustness are of interest to a variety of users.

Assessing Usability Goals
In this brief overview of GPS technology within an outdoor sporting environment, we highlight some classical usability issues and suggest possible solutions to these issues.

We looked at learnability and discovered that many GPS devices did not include even simple help menus. As we all know, most users read a manual only as a last resort! Most of us expect the device itself to answer our 'how to' questions.

In general, most GPS units have a high utility with regard to navigation, their main function. However, the input systems employed had a low utility as it takes a significant amount of time to input data into the device.

From a device safety point of view, GPS receivers can generally be regarded as safe. However, in terms of personal safety to the user, giving attention to the device while performing specific tasks may be hazardous in the same way as driving a car while talking on a cell phone.

A survey was conducted of GPS users’ opinions of their receivers and many who completed the questionnaire commented on the efficiency and effortlessness of the GPS receiver interface.
Effectiveness: There is no doubt that GPS receivers are highly effective in that they can help the user to navigate to a specific geographic location, within an accuracy of about five meters.

Memorability: GPS interfaces were generally found to be relatively easy to remember, as simplicity is an inherent part of GPS handheld receiver design. What is not easy to memorise though is the data stored on the device, particularly waypoints, which could become confusing with large sets of data. This confusion arises from the small number of characters allowed to identify waypoints, as well as the fact that additional information on a waypoints is not always shown alongside the waypoint - except as a small image.

Defining the User and the Users Needs
In a GPS-based sport like geocaching, users need to navigate through an outdoors environment, but their main task is not navigation. The user will typically be a relatively fit individual, who will most likely need to cross difficult terrain, such as rocky mountain paths, without having to slow down to use the GPS. As referred to earlier, the user’s mobility and senses must not be hampered by the system, since lack of mobility or distraction could compromise personal safety (stumble over rocks, fall into a ditch...).

The user will require at least knowledge of basic handheld devices, and a basic knowledge of how to use the specific GPS device. Knowledge of the buttons and controls for a specific device is needed, as is knowledge of the display. The user also needs a basic technical understanding of how the device functions. For example, it is important to understand how the GPS receives satellite signals and how it calculates the heading of the user. In field studies, users who did not understand these points became frustrated and complained that the device was not working properly.

A basic skill can quickly be acquired and is sufficient for basic operations, but extended use is required for a higher level of skill, such as complex mapping and orientation tasks. It is often at this point where users tend to become more positive about the 'user friendliness' of the device. Generally, GPS requires higher levels of skill and education than cell phones. The user needs not only basic reading skills, but also an understanding of simple map reading and geographic coordinates.

It was found that formal tutoring in the use of GPS technology and GPS devices help to improve the user’s performance. An understanding of basic mathematics and geography was particularly helpful.

As with most handheld devices, the physical attributes of the user constrain the design options for a GPSr. Individuals older than about 8 years old should find it easy to manipulate the buttons with the fingers of either hand and the device should sit comfortably in that hand. This implies that the complexity and physical configuration of GPS receivers make them unsuitable for children.

The motor capabilities of the user will also affect their ability to use the device effectively. Most, if not all, current GPS receivers require buttons to be pressed and also the device to be held in a specific position in front of the user. In addition, tactile (feel the difference between button shapes and their action) and visual (discriminate shapes on the display) capabilities are required. Some receivers offer audio capabilities through which the users can obtain basic navigation information without having to look at the display. However, since the user still needs to be able to gain information from their surroundings as well as the device, fine motor skills and sight can be regarded as essential.

Device input and output options
Many GPS-based sports involve completion of tasks within a certain time. Users who need to quickly input GPS information find this nearly impossible and thus important data may be left out if the user is running out of time. Current designs do not support this need. GPS receivers have few buttons and often each button has multiple modes. Many models also use a four-way rocker pad to navigate in the display.

The output from the device is traditionally an LCD display which is only three or four centimetres wide. Wearable devices, such as a heads-up displays or headphones could alleviate the need to view the screen and to hold the device in the hand. Of the users interviewed, 36% said that they were not in favour of using wearables, presumably because the device will become intrusive and require a level of attention that detracts from the real task.

To address this problem, an Audio GPS was designed by Simon Holland and David Morse mainly with 'sighted mobile computer users' in mind. This system only needs to give spatial information, and so does not need to employ speech output. It uses a 'virtual acoustic display' for the output of information. An audio signal is transformed into a binaural signal which is played through earphones, given the illusion that the sound is emanating from a location around the user. The user is still able to hear sounds from their surroundings and any conversation going on. This system has the potential to reduce or eliminate the need for the user to refer to a display. With the development of Bluetooth headphones, the user would also not need to have wires connecting to the device, making the system fit nicely into a pocket and on the head.

Another solution could be heads-up displays which would project information onto a lens in front of the user’s eye to create an 'augmented reality' of their surroundings. However, research indicated mixed feelings about heads-up displays. Some users see augmented reality as intrusive or irritating, especially when it hampers their natural view of the environment.

If head-mounted displays were used in a sporting environment, they would need to be water-resistant and light, allowing the user maximum mobility.

Some more ideas for new alternatives, or enhancements of existing ones:
• Speech input to annotate a piece of information, such as a waypoint. Of all possible solutions this seems to be the best, as the user would be able to record useful comments quickly and in a natural fashion. Ambient noise may however be a problem, which may require the use of noise-cancelling microphones.
• Cell phone-like button arrangements have been employed in a number of GPS units, but they have yet to replace the normal eight buttons and a rocker pad button configuration as the standard. There seems to be a move towards stylus-based input, but this will not be suitable for applications where the user is constantly on the move. Unlike telephones and calculators, there is no industry convention for GPS interfaces, but there seems little doubt that a button configuration similar to a cellular phone would be useful for certain GPS types.
• Another type of input would be a simple button pad that consists only of buttons and fits into the user’s hand. This could be used in one hand and have output via audio channels. Such a device could be small and linked via Bluetooth to the GPS receiver on the users back, meaning that the user would not need to hold his arm up in order to receive GPS signals.

Conclusion
We have only touched upon some key GPS usability issues. We have found no evidence in the literature that GPS designers had specific usability goals in mind and we suggest that there is room for some focused usability research.

Most conventional GPS receivers are specifically built for the outdoors, with waterproof sealing and sturdy, drop-resistant design. These features suggest that the designers have taken some of the things the user will typically have to face into consideration. However, much more attention should be paid to the context of use, which includes a closer look at the variety of environments, specific user tasks and interaction modalities.

It is likely that we will see alternative input and output solutions in future, including advanced voice recognition features and major advances in heads-up displays and spatial sound output. More important though, is the need to research the human side of GPS use. While most GPS receivers are highly usable, the level of knowledge and the level of attention needed to use the device can be quite high and these problems can be addressed in a number of ways.

Until such time as technological advances significantly reduce the need to attend to the user interface, one of the most obvious ways to improve usability would be to make a Help facility and manuals available on the device itself.

Rodney Sloan and Jacques Hugo
Department of Information Science, University of Pretoria
jacques@usabilitysa.co.za
sloan@tuks.co.za

Further reading
Pascoe, J., Ryan, N. & Morse, D., 2000. Using While Moving: HCI Issues in Fieldwork Environments, ACM Transactions on Computer Human Interaction , vol. 7, pp.417- 437.

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