The system could in their opinion be useful for preplanning, performing tasks and precise navigation, as well as sharing waypoints, routes and assembly points in the team.
Users in study 1 mentioned the following desired main functionality: a navigation view with waypoints and own position visible on an egocentric rotating zoomable map, compass, optional tracks (breadcrumbs), and adjustable filters for what is shown such as grid or target symbols newer than a certain age. The responses are put in headlines according to analytical themes. The results from the focus groups were analyzed together with ratings and free text answers in the questionnaires.
A total of 27 officers from studies 1 and 3 took part in the focus groups. In the focus groups, questions involved how to make the best use of a future DSS, what problems could arise, what functions and information should be most prioritized, usability issues, performance and ergonomics, use in darkness and how the technology could affect team behavior. A total of 24 officers and soldiers from studies 1, 2 and 3 responded. The questionnaires contained questions regarding general usability of the GPS, details concerning screen, map, ergonomics, buttons and other impressions after use, as well as free text questions. It w as carried in a pouch on the chest for easy access, with screen visible and transparent soft plastic over the buttons. The DC50 tracking transmitters were mounted on the platoon leader’s and squad leaders’ combat vests. Simultaneous tracking of up to 10 transmitters is possible, with positions updated up to every 5 seconds. Its maximum range is ~8 miles, but in forested and non-flat terrain the practical range is about 2 miles. It also showed own position and positions of important stationary POI’s. This provided access to near real- time positioning of other team members’ positions, adding the functionality of a Blue force tracking system. The DC50 sends its GPS based position via VHF radio to the Astro 320 device. In study 2 and 3 the similar Garmin Astro 320 GPS receiver together with the Garmin DC50 GPS transmitter were used (system B, see Figure 2). The map rotated around the own position in an egocentric view, using the digital compass, such that what is in front of you in the terrain is shown at the top of the map. In study 1 the Garmin GPSmap 62stc (system A, see Figure 1) was used, showing own position and positions of important stationary POI’s overlaid on a digital vector map.
Both type A and B GPS devices used the same vector map style, have a 2.6” color TFT screen with a 160 x 240 pixel resolution readable in sunlight, and have luminance level adjustable for use in dark conditions. GPS receivers used in the above mentioned studies were commercially available rugged handheld devices of similar design, with the addition of a radio antenna for type B.
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