I bought a BU-353 recently. Plug it in, it starts sending NMEA sentences at 4800 baud. Gpsd was talking to the device, and I used "gpspipe -r" to cat the data into a file. I've got complete second-by-second track information for a trip to the bay area i took a couple months ago. I haven't gotten around to figuring out how to draw it nicely on a map, but the data is there.
With a laptop I could record the NMEA, but I don't exactly want to carry a laptop to map a hiking trail which is the problem. There are a few things I want to use tracklogs for. One is making maps of trails, another is geotagging photos. Basically you match the timestamp on the photo to the timestamp of a tracklog point to find your location when you took the picture. Doing this in software is a lot trickier if you have to calculate based on speed, and direction where you were instead of just taking the nearest point. Additionally only making data points when you move at least 50 feet is really troubling as I can make side trips off the trail that don't register at all. GPS seems to make a random walk around the location it is really at. Now I had the idea that if I had two gps's both making tracklogs, one hidden in my car, and the other with me on the trail, that I could use the fact that one is standing still to correct randomness of the one that travels with me. It is really frustrating to walk a loop trail, and not have the end match the beginning because the accuracy drifted from one visit to the next.
Daniel> Garmin does it like that. Actually the garmin I have is a little more clever. It does something like this: if the new point is a reasonable projection from the last two points, drop the last point. If you are clicking along at a constant speed and direction, it'll drop the intermediate redundant points from the track data. That's with a 12CX. Ends up giving you pretty good fidelity on the route you took without wasting precious storage.
I seemed to remember that was only one of the options when I played with it at the store, and pure time hops was another option. In any case the logs I have seen so far, even ones from hours of logging are only a few kilobytes, and I have 22 megs to work with so I would at least like the option of more detail when I want it. _______________________________________________ PDXLUG (a Portland Linux user group) mailing list [email protected] http://lists.pdxlug.org/mailman/listinfo/pdxlug IRC: irc.freenode.net #pdxlug & #orlug
