The Problem

Our application requires good GPS signal to locate the glasses and allow the user to discover time portals. After much testing we found that the on-board GPS system of the Moverio BT-200 was rarely able to function. This may be because of the frequent overcast skies here in the UK, though even some relatively clear days caused difficulty. We tested it alongside iPhone GPS (with WiFi turned off so that it used GPS only), and found that even when the phone was functioning well, the BT-200 failed to obtain a signal. In addition to testing with our own software, we made use of the publicly available GPS Status & Toolbox Android application which will run on the smart glasses. It reported the same difficulty in obtaining a position fix.

The Solution

We decided to try an external GPS module. We purchased one of the popular Dual XGPS150 bluetooth modules. Ours is the XGPS150E, where the E stands for ‘Europe’. Each module has its own serial number reported through bluetooth, so they can individually ‘pair’ with different glasses. This is important as there can be multiple users near each other and we didn’t want the glasses confusing one GPS module with another.

Wearing Dual XGPS150E

Dual XGPS150E bluetooth GPS module worn on wrist strap.

The module pairs successfully with the smart glasses, and shows good satellite visibility in the GPS Status & Toolbox, even when the on-board GPS may not be reporting any visible satellites at all.

Software integration with our game was relatively straightforward. We found that we could obtain a connection socket to it and simply read GPS coordinates as lines of text. Source code can be found in the technical notes here.

The device functioned succesfully within the game to provide GPS location as required.