Spaced Out ::

I’ve finally caved in and bought a GPS. Being not remotely interested in satnav, I have had limited need for a GPS, however it was Neogeography that finally got me interested in some of the potential uses. In it, Andrew Turner reviewed some GPS loggers. No screen, limited settings, just data collection.

On the this years first year field course, I have liaised with the Rights of Way officer at Carmarthernshire County Council and the students will be going out and surveying potential rights of way using “definitive” mapping from the 1960s. Clearly then its beneficial to have tracklogs from a GPS; absolute accuracy is not esential for this task and low-cost units provide an ideal piece of kit that is “fit for purpose”.

Our department have a horde of Garmin Gekos used for various purposes and these are fine for the task (provided you have the bespoke usb cable to access the tracklogs). I therefore thought I would purchase a Sony CS1 GPS logger to see how it would fare. The first thing to note is its diminutive size, single AA battery that provides upto 14 hours of continued logging (or more if you can get ahold of a Li-Ion). The unit comes with ~31Mb RAM which provides over 300 hours of logging or somewhere around 75000 points. Thats bloodly good in comparison to the competition. Its a standard 12 channel receiver, although no EGNOS/WAAS by the looks of things (not explicitly stated either way, but the “claimed” accuracy suggests not). There is only an on/off button and no settings. And this is probably the units greatest weakness; the logging interval is 15s and you CANNOT change it. The CS1 was designed for tagging digital photos and 15s is fine if you are walking. Not so good if you are cycling or snow boarding (SONY: can you please make this a changeable setting).

In operation the unit works just fine, taking around 1min for initial satellite acquisition. Probably best to put it on the top of a rucsac to give it maximum aerial visibility, however stick it in a plastic bag to keep it waterproof. When finished, you can use a standard mini-usb cable to attach it to a PC and, low and behold, it appears as a drive letter in exactly the same way a flash drive would. Sony has got this part spot on. Just copy your tracklog on to your PC and run gpsbabel to convert it in to something more useful. Its in NMEA format so use the following command line to convert to KML and load straight in to Google Earth:

gpsbabel -i nmea -f 1.log -o kml -F 2.kml

I can’t believe how simple this all is!! You can alternatively convert it to GPX and then in to SHP for loading in to a GIS. Many thanks to Tim Woolford for the heads up on the Sony unit.