Garmin announces the new Colorado handheld GPS at CES

[philpugh]

Sorry, to complete the answer to AllyCat's questions...

I have the tracklog set to log every n seconds (30secs in this case). The Auto mode probably does what you describe i.e. 'decimates' the tracklog, recording at changes in direction etc. This caught me out the first time with my GPS60 - couldn't work out what was going on. I want a tracklog to record where I went - not an approximation that isn't true. The first time wit hthe GPS60 was on a canal boat, the tracklog had us going overland quite often! The auto mode tends to end up with something that is more like a route plan than a tracklog, a set of points with a straight line between them.

The whole archived tracklog from the C300 followed very faithfully the paths/tracks that I had walked.

Whoaa.. just a second...

A more detailed look at the archived track log shows that it is logging the temp as well. The file does not contain LF/CR so it's a single line in a text editor - I just did some quick editing and found an extra field in each log interval. The complete individual log is:-

(trkpt lat="54.324916" lon="-5.538181")(ele)65.4(/ele)(time)2008-02-06T07:38:10Z(/time)(extensions)(gpxtpx:TrackPointExtension)(gpxtpx:atemp)16.7(/gpxtpx:atemp)(/gpxtpx:TrackPointExtension)(/extensions)(/trkpt)

Once again I changed the angular brackets for conventional brackets and modded the Lat/Long. The temp seems to be reading higher than ambient - which would indicate that it is probably using some in-unit sensor rather than measuring true ambient.
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Phil

[AllyCat]

Thanks Phil, that's interesting.

My experience with GPS goes back to the early days (GPS45) when memory was valuable, so the economies that Garmin made with data storage were justifiable. However, I've been surprised that (until now?) Garmin appear to have made so few changes to their storage algorithms. But, the characteristics have never been explained properly in their User Manuals, hence the reason for my question.

However, your description of Auto mode is not how I understand it. The logging interval (which creates the Active Log) can be either "fixed time increment", "fixed distance increment" or "Auto". In Auto mode, the GPS creates a new tracklog point whenever the track deviates (even very slightly) from a straight line. Personally, I've rarely used it, because I found it filled the memory much too fast. I prefer a time increment of typically a minute, which I know will give an adequate indication of my walking route, but I can predict how many days, etc., that I can record logs before the memory will be full.

The Active Log is just a "continuous" log (except that Garmin report a new track fragment whenever position is lost, even for a brief interval), but (any) part of it can be "Saved" to one of a defined number of storage locations (typically 10 or 20). Now, in my GPSs this process has done two things, firstly it strips out all the time data and secondly (if the track is long) it "decimates" the track. This is presumably beacuse only 250 or 500 "locations" are reserved for each Saved track, so it strips out points which are nearest to a straight line, leaving only the 250 or 500 "most significant" points. This decimation process generally has little effect on a day's walk, but may well have severe effects on complex or very long (several days) Active Log tracks.

All the early Garmins could be put into a "diagnostics mode" which included a temperature indication. I understand it was of the crystal oscillator, for accurately calibrating the system clock. However, I can't see why they're recording it in the track log of the Colorado.

Cheers, Alan.
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[philpugh]

Yes - my GPSII+ could be put into the 'internal' mode. Temp is now made available on the main screen as an option to replace one of the fields. The C300 is also sold as having that feature. I was suprised to see it in a tracklog. I suspect the temp is the internal oscillator temp, which is required as part of the calculations doen to get a fix. I have turned off the logging of atmos pressure - I suspect this would appear in the log as well. (Will have to try it now )

I understand what you say about the different modes for tracklog. The GPS60 (like the C300) comes with AUTO mode set. What I saw with the GPS60 was the effect of decimating a large tracklog to fit into the limited memory. So a days sailing on the canal resulted in a very poor representation of reality.

My GPSII+ only had "log every n secs/mins" - and it worked how I wanted a track log to work. I have set the C300 for every 30 secs and will probably leave it at that. The majority of my tracklogs are done on my Zycast 289 as I can turn it on and forget about it. A 2GB card lasts a very long time!
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Phil

[Jay1967]

[philpugh]

Did a good long walk (nearly 9 hours around the hills above Buttermere) on Sat.

The C300 did reasonably well except I got very poor results with new NiMH 2800mAH cells. The first pair I tried only lasted 3 hours (with no backlight). This was up to the point it switched off - I had the low battery warning after 2 hours! I reverted to Duracell at this point and continued the walk. Got back home and found there was an update to the firmware addressing this (released after I set off in the car for the walk). Will have to try them again.

Of course the problem will be compounded by them being new cells - only had the one charge - so it's going to be another 3 or 4 cycles to get the optimum performance out of them.

Otherwise - the home made map I did worked well and the route following got us safely off High Stile in heavy mist - nothing to take a visual bearing off. It's now got it's first scratches - ascending Hay Stacks of all places. The barometeric altitude (using auto calibration) was pretty accurate compared with the summits of the hills we walked.
It was clipped to the outside of the rucsack and survived the rain (with 40mph+ winds) - the battery compartment and SD card was dry - so no concerns there.
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Phil

[philpugh]

The firmware update I mentioned in the previous post also significantly improves the initial start up time for the unit.

Originally it was 40 secs plus - it's now down to around 10-15 secs and that's with the in-built basemap and my home grown map with contours for most of North England. Very impressive. GARMIN also claim to have improved (under certain conditions) the initial satellite acquisition time - but it's been more than good enough for me as it was.

Another improvement for GEOCachers out there; it now holds 2000 cache locations at a time - thats up by a factor of 4.
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Phil

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