Discussion: Software and GPS tracker thingys

What sort of software do you recommend for doing something with the data from a GPS tracker thingy?

Any recommendations for useful and easy-to-use software?

I've looked at Gartrip, motionbased.com, sportsim, GPSvisualizer.com and the Garmin software that came with the GPS I've got (forerunner 201). I think lots of people like Gartrip, but it struck me as a bit difficult to use (though I'm a bit of a clutz when it comes to software).

Memory-map.com Navigator is a moving map program with the tools that should do the job (supports scanned maps, calibration and importation of tracks.) It also supports calibrated USGS tiffs that can be downloaded individually at little or no cost from the internet or ordered by state as a merged 1:24,000. Capabilities include 3D rotation and PDA support (very effective cheating potential.) A full state at 1:24,000 can be loaded into a handheld. (As a dealer I can offer discounts on the Navigator and Discoverer if there is sufficient interest.)

As for a receiver, I'd look into the new SIRF III chip, the one that's so good under foliage. I get 6-7 sattelites under redwoods with my Holux SIRF III. Haven't used it with scanned maps. It may not be available on a logger as yet but that's sure to come.

Here is the first race experiment with RG gps tools. Take a look at H35, there is two versions of my route, gps and drawing. #2 I did not draw correctly, gps route is more accurate.

Compare also animations. Gps makes me look fast on roads.

Sandis Sprint and middle event date 2006-04-07 (today)
Location

My route Sandis middle week ago:
http://www.routegadget.net/kokkens2006/cgi-bin/rei...

Family Oikarinen used FRWD last weekend:
http://av.nettirasia.com/reitti/cgi-bin/reitti.cgi...
http://av.nettirasia.com/reitti/cgi-bin/reitti.cgi...
http://av.nettirasia.com/reitti/cgi-bin/reitti.cgi...

Some elite routes ("GPS" before name):
http://av.nettirasia.com/reitti/cgi-bin/reitti.cgi...
These are not too well adjusted on map, these are posted and adjusted by organizers. This was TV event and GPS was used to view and compare routes on TV (it was great 2 hour TV show by the way). It can be seen in Finland again today:(Urheilukanava 19:30 Finnish time.
Gps + cell phone system was the one I mentioned here: http://www.attackpoint.org/discussionthread.jsp/me...

One of the drawback's of the SiRF III's under trees (and probably any GPS under trees) is that while the new technologies hold onto the signal, it's distorted somewhat so the track wanders around a bit.

Probably not much worse than 20m, and usually less than 10m typically in the forest (although the leaves aren't all out yet.) This is fine for rough mapping of trails that you can't see on a basemap, and fine for RouteGadget/overlays.

However, it's not great for pace-calculations, because as the +/- 10m error swings around, it can make you look a lot faster or slower than you are. (Note that this is in-forest - in the open it seems much more accurate, as GPS should be.) Also, this is mitigated over longer distances - e.g. your average pace for a given mile or kilometer (or a whoel workout) is still pretty accurate as +/-10m when divided by 1000+m isn't a big deal.

Also, as-expected by the design of the Forerunner (and most GPS-only in-forest solutions), the altitude has about 2x the horizontal errors, so it swings around up to 20m or so. This makes the elevation profile of a run look terrible - it would be much better to simply look up altitude in a database based on lat/lon, like the G Maps Pedometer now does, to get an elevation profile.

An unfortunate side effect of this elevation issue is that the calorie-counter thing seems to be pretty far off accurate - so you can't really use the number of calories spend as a quantitative measure of total effort.

If they added a baro-altimeter that's filtered with the GPS the altitude profile (& calorie count) would be much better. (maybe there will be a Garmin Forerunner 405??)

I don't think you have to "filter" the pressure-gauge altimeter with GPS, just discipline it to mean GPS z with a time constant of ~10 minutes.

The Garmin units that does have the barometric altimeter allows for something known as auto-calibration. This means that the GPS elevation is used to calibrate the barometric altimeter, to compensate for weather imposed pressure changes. The GPS elevation affects the barometric altimeter in an exponetially decaying way, hence most influence at start, then just a little, to take care of the pressure changes.
Hence it's rather the opposite, a GPS elevation filtered by the pressure sensor, which you can read on the display.
If I walk with my Forerunner 301 (GPS elevation) and eTrex Vista (pressure sensor) at the same time, I can easily see the better elevation profile recorded by the Vista, when I compare the track logs in Mapsource.

Anders

Do the FRWD GPS tools have a barometric altimeter? This would give it a considerable advantage!