Sunday, 21 October 2007

Sonify - first GPS data from Sunnto watch

Today I tested my new GPS watch. The purpose behind the geeky toy is actually to feed GPS data to Max/MSP for sonification to evaluate our new interactive aesthetic sonification toolkit.

Described as the smallest GPS watch or wrist-top computer in Suunto's jargon, the x9i's features include:

Altimeter: altitude, vertical speed, altitude alarm
Barometer: Sea level pressure, absolute pressure, weather trend graph, temperature, weather alarm
Compass: Bearing, north indicator, bearing tracking
GPS: Speed, distance, routes, waypoints, tracks
Watch: Calendar, 3 alarms with date, dual time, stopwatch
Water resistant to 100m / 330ft
USB computer connection and lithium ion battery charging
PC software for route planning and record graphing
Upload data and view tracks on Google Earth™

I was keen to get a decent satellite fix because the reception in my house or even from on the balcony is never sufficient. So the geek in me took the watch to Tunks Park launching ramp on Middle Harbour where I would be assured of clear skies and plenty of satellites in view. Indeed this worked fairly well. The only instances of 'walking on water' and other inaccuracies derive from momentarily loosing a fix or ambiguous calibration of my map in the software. Like most GPS software, you can load your own map so I used a GoogleEarth satellite photo background for the trackpoints. The compass and thermometer seem fairly reliable while the altitude reading, despite frequent calibration, seems less steady, probably influenced by barometric changes. So long as the location was very open, away from cliffs and overhanging trees, it worked well. Of course my handheld Garmin with its more substantial aerial has more robust reception but it really chews the batteries and is quite bulky.

Suunto Trek Manager software graphs trackpoints, waypoints, altitude, weather, GPS coordinates, time and distance measurements. Normally intended for Windows, I am running it on Parallels Desktop software on my Apple Macbook. From here the data can be exported as text files that, in turn, can be read into a matrix in Max/MSP for sonification and interactive manipulation (see example below in which waypoints from Linda Beilharz's [my cousin] Greenland icecap crossing expedition are loaded and plotted in Max/MSP). Most GPS softwares are not available for Apple OSX. I use MacGPS Pro adaptation software to convert feed live from the Garmin GPS but the Suunto Trek Manager provides much more elegant graphical visualisations of the data using Win emulation. The Suunto Track Exporter is used to export the trackpoint data to GoogleEarth live maps online. This will be handy in Japan because free and recent topographical maps are few and far between.