February 10, 2008. Current method for making a GPS track log on Google Earth.

I use a Sony GPS-CS1, a $100 device that records GPS coordinates every 10 sec. This is no longer sold by Sony but can be gotten easily on eBay. You can take it on a hike, walk, or car drive. The data is downloaded via a USB cable onto a PC (can't transfer directly to a Mac unfortunately). I transfer the .log file to my Mac by a key drive, then convert it to a .gpx file using the free software HoudahGPS (there is certain to be an equivalent program for the PC). This file can be opened by Google Earth.

Google Earth is a free download from the google site. I had some trouble figuring out how to use the software but managed in the end. When you load the data, it shows up first in "Temporary Places". You must click on the track to make it show up in the map. If you want to save it, you have to save it to "My Places". When you want to look at it again, you should check the box next to the track (and uncheck any tracks that you don't want to see).

I also tried using a $100 Garmin eTrex GPS unit. This has the advantage that the data can be directly downloaded into Google Earth on the Mac - in order to download directly like this, you have to get the pro version of Google Earth, which is ~$20. The Garmin device is designed to do a lot more things than just data log, so it is larger than the Sony and seems to run down its battery much faster. After using it for a while, I went back to the Sony. Another consideration however, is that the Garmin accuracy seems to be noticeably better than the Sony (for instance, the track for a car seems to stay closer to the road with the Garmin than with the Sony).