GPS question....

[tomimcmillar]

hey All, question for you GPS gurus.  I've had my Garmin, Vista HCx, for about a month now, working on some quirks I've found...

Altimeter:  I have the unit calibrated to my home elevation, 460ft.  When I throw the bike on the car and drive to the day's ride venue, then power up the GPS, it defaults to the elevation I calibrated it at, 460'.  It won't automatically find the elevation at the new location, so I've been needing to calibrate it each time I start a ride that doesn't leave from my doorstep, sort of a pain in the ass.  Is this normal, or am I missing a setting in one of the menus?  Or should I just turn it on when I leave the house and let it do it's thing during the commute to the trailhead?

Accuracy:  For recording tracks, I have it set for 'Automatic/Normal.'  Did this as a starting point, not knowing how large of a record it can hold in memory.  At the end of the Shen100, I had a distance of 95miles, so I'm off by a smidge and looking at the track from my last tour, I can see where corners were cut due to the straightline distance between recorded points.  Imagine that upping the recording rate would resolve this, but not sure about file size as the number of recorded points will increase.  Curious what settings ya'll use for a day long outting?


tia,
tomi

[jonesy792]

I calibrate the altimeter using the gps altitude, I don't know why it doesn't use that number to begin with.  Unfortunately the altitude number on my unit tends to drift over time and needs to be recalibrated every other day or so, no biggie for day trips but kind of a pain for multi day stuff.

Tracks still confuse the hell out of me, I have mine set to auto/normal also.  When I downloaded the tracks from my CT trip into topofusion all of the tracks on the download list were lacking detail (i.e. cutting corners etc.).  But when I told topofusion to "download all tracks" it downloaded an additional track that was of perfect quality but was not on the download list.  I have also randomly lost tracks on the unit. 

[DaveH]

For saving tracks, the best thing to do is get a mircro SD card and have the unit write data to it.  You can put a ton of data on a 2GB SD card.  If riding nonstop for days the unit delineates tracks by day, names them with a date timestamp IIRC.  When I had a vista I think for routes I wanted decent resolution I set it to collect at 6 second intervals. 

I collect at 1 second intervals on my 705 now (required for the power data) and just using the built in 500MB memory there is plenty of room for at least a few months including CTR and similar rides.

The issue you run into is when you want to use that data afterwards.  The Vista (unless it's changed?  anyone?) has a track limit of 20 and point limit of 500/track.  At my 1 sec resolution that get's me all of 8.33 minutes of track uploaded to a vista!  Memory is so cheap, man I'm getting tired of these friggin limitations I run into with Garmin products...but whoa get off the soapbox harris...anyway - if you want to navigate a route using track data you've previously collected you'll need to use TF (or other SW) to simplify the track.  A  lot of detail can be lost, but TF is very good at removing points on straight sections and not on curves, retaining the original track's route pretty well.

Altitude?  I think DEM data is just as good...I don't worry much about elevation, if a track looks wonky I just attach the DEM in TF.

[DaveH]

Ah, forgot this part...

The vista has a 10,000 point limit.  So if you did a day long outing that was, say 12  hours and you wanted to maximize the resolution and still get it all on the unit sans SD card, divide the number of seconds in 12 hours (or whatever) by 10,000 to get the spacing in time for each recorded point.  In this case that works out to 4.3 seconds, so the highest resolution you could do for that ride is 5 second spacing.

Now, I'm assuming you can control recording rate by the second which I know you can do in the 60 cs but not real sure of the vista.  Anyway, you get the drift.

[tomimcmillar]

thanks guys!  Found some small blurbs about the altimeter and auto-calibration, will need to play with it some more. 

Where'd you find the stats on the point limits D?  I've found the 'manual' for this thing to be a bit lacking....

[DaveH]

Garmin documentation is anything but.  For some devices (ahem, the 705) firmware is changing so rapidly they clearly have just thrown in the towel on getting stuff documented properly.  You have to be a geek and sleuth it out on user forums, or even worse, trial and error.  IIRC there is a 10,000 point limit on the packaging...it might also be in the back of the manual?

[Falstaff]

For saving tracks, the best thing to do is get a mircro SD card and have the unit write data to it.  You can put a ton of data on a 2GB SD card.  If riding nonstop for days the unit delineates tracks by day, names them with a date timestamp IIRC.  When I had a vista I think for routes I wanted decent resolution I set it to collect at 6 second intervals. 

Ah, forgot this part...

The vista has a 10,000 point limit.  So if you did a day long outing that was, say 12  hours and you wanted to maximize the resolution and still get it all on the unit sans SD card, divide the number of seconds in 12 hours (or whatever) by 10,000 to get the spacing in time for each recorded point.  In this case that works out to 4.3 seconds, so the highest resolution you could do for that ride is 5 second spacing.

Now, I'm assuming you can control recording rate by the second which I know you can do in the 60 cs but not real sure of the vista.  Anyway, you get the drift.

Does anyone know how the Vista HCx handles writing tracks to the SD card once the 10,000 point limit for a track is reached on a single day ride?  I understand that without the SD Card it will either stop recording the track or "wrap when full" based on if the box is checked on the track log setup screen - so data is lost one way or the other.  But I'm wondering how it handles writing to the SD card in the case of a very long single day ride and if data lose can be avoided.  Or is the only option to record fewer points so the 10,000 point limit is not reached.

Thanks.

[Marshal]

Does anyone know how the Vista HCx handles writing tracks to the SD card once the 10,000 point limit for a track is reached on a single day ride?  I understand that without the SD Card it will either stop recording the track or "wrap when full" based on if the box is checked on the track log setup screen - so data is lost one way or the other.  But I'm wondering how it handles writing to the SD card in the case of a very long single day ride and if data lose can be avoided.  Or is the only option to record fewer points so the 10,000 point limit is not reached.

Thanks.

Not sure if this answers your question but if you turn off the Vista it will write to the SD card.  I am pretty sure it also writes to the card when if you just turn off "track".  Sorry its been a few yrs since I figured out what it would and would not do. 

From a practical point of view, between battery change outs and stopping for the night, the only time I max out my Vista's track record mem  is if I forget to turn it off at night on a multi day--I am guessing I have it set to record about 15 hrs.  I usually discover this mistake when my batteries quit the next day. 

[Falstaff]

Thanks for the thoughts.  I'm planning a ride that will take me through a full day and night but sounds like just turning it off and then back on at some point we achieve what I need.  Time to go test that.