Problem with GPS

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Moni

 
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Re: eTrex Vista HCX

by Moni » Fri Jul 24, 2009 2:05 am

Assuming your livingroom has a roof......GPS doesn't work indoors. You may get a little signal but that is through windows, not the rest of the building. Elevation accuracy goes to hell with less than ideal reception.


Actually with the new high sensitivity chips, it does work in your livingroom. I was skeptical at first, but set my Vista HCx up in my office at work and then booted up the GIS - the receiver told me I was about 2 offices down (so 30 feet) from where I really was! I don't even have windows. The new chip really makes a huge difference is worth upgrading to.

The track that MtnHermit submitted shows classic multipath error. The patch antenna is normally more resistant to multipath problems but must be horizontal to do so, while the quadhelix, when held vertically, is more susceptible to this problem.

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kolbi2112

 
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by kolbi2112 » Sun Jul 26, 2009 7:25 pm

I did a 12-mile trek at the El Capitan Open Space preserve yesterday. No big trees and no canyons and it seems my GPS performed very well. At the 5-mile trail marker I had 5.15, which I believe is within the margin of error. You can see from this image that there are no multi-path errors, and the track profile shows a very symmetrical pattern (it was an out-and-back hike with a slight difference towards the end due to some off-trail exploring we did). The only changes I made were new batteries and GPS placement (I left WAAS enabled and did not do a hardware/software reset). But, instead of hooking it to a clip below my shoulder I hooked it to the top of my pack just behind my neck, facing out at a slight angle but not nearly flat. The only drawback here is that you can't read it unless you take your pack off.

So anyway it looks like the unit is fine, just need to make some adjustments. Glad I don't have to buy a new one. Thanks to all for the feedback.

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Diego Sahagún

 
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by Diego Sahagún » Mon Feb 01, 2010 12:42 am

I'm new in the GPS' club. Today I've been given a Garmin etrex Vista HCx for my birthday that will be on wednesday. I hope that I can enjoy it...

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Howard71

 
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Battery Saver Setting?

by Howard71 » Mon Feb 01, 2010 5:30 am

I'm not sure about the Etrex, but I've had similar problems with my 60CSx when I have the system set to "Battery Saver" rather than "Normal." I'm not sure why, but the battery saver results in more variable locations. I also found that with the battery saver on I could cover a mile while I sat still for an hour eating lunch....

Howard Snell

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Diego Sahagún

 
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by Diego Sahagún » Mon Feb 01, 2010 10:30 am

Howard, take two full-charged spare batteries more instead of putting your navigator in the save mode. It'll show you bad readings if then as you've said.

I bought 4xAA Eneloops, Sanyo says that they're good in cold condition and the percentage of discharge after a year is less than other batteries. Is that true :?: I'm thinking on buying 4 more batteries for 3-4 days' hikes. What do you think about that :?:

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Diego Sahagún

 
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by Diego Sahagún » Wed Feb 03, 2010 12:29 am

I don't know if I'm going to like being 40 years-old :?

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Howard71

 
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by Howard71 » Wed Feb 03, 2010 4:04 am

Diego Sahagún wrote:I bought 4xAA Eneloops, Sanyo says that they're good in cold condition and the percentage of discharge after a year is less than other batteries. Is that true :?: I'm thinking on buying 4 more batteries for 3-4 days' hikes. What do you think about that :?:


Diego:

I'm not familiar with those batteries. However, with Duracell "Ultimate" alkalines I think I can usually get at least two days of hiking, maybe more per set in "normal" mode in my 60csx as long as I turn the GPS off when I stop and don't use the backlight screen.

Howard

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Buz Groshong

 
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by Buz Groshong » Wed Feb 03, 2010 4:10 am

Diego Sahagún wrote:I don't know if I'm going to like being 40 years-old :?


Hey, don't complain! Sometimes it seems it would be nice to be 40 again! Then again, 40 was kind of young and stupid and I hadn't yet climbed any mountains. :wink:

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Diego Sahagún

 
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by Diego Sahagún » Wed Feb 03, 2010 10:02 am

Thanks Buz :!: Still there're many mountains to be climbed :)

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Diego Sahagún

 
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by Diego Sahagún » Wed Mar 10, 2010 6:08 pm

D'you know how to calculate the geometric height using a Garmin Vista :?: All that I can check is the barometric altitude so I often have to calibrate it

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Day Hiker

 
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by Day Hiker » Thu Mar 11, 2010 8:35 am

Diego Sahagún wrote:D'you know how to calculate the geometric height using a Garmin Vista :?: All that I can check is the barometric altitude so I often have to calibrate it


Go to the satellite page (via the Main menu on the Vista?), and one of the options will be "GPS Elevation." This will display your elevation as determined by the GPS, as opposed to the barometric altimeter.

Also: I have a 60CSx, and when marking a waypoint, the unit uses the barometric altimeter, but when averaging a waypoint, the unit uses the GPS elevation. It comes in handy to know this if you want to choose which elevation to use. Your model may be similar.

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Diego Sahagún

 
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by Diego Sahagún » Thu Mar 11, 2010 9:49 am

Day Hiker wrote:
Diego Sahagún wrote:D'you know how to calculate the geometric height using a Garmin Vista :?: All that I can check is the barometric altitude so I often have to calibrate it


Go to the satellite page (via the Main menu on the Vista?), and one of the options will be "GPS Elevation." This will display your elevation as determined by the GPS, as opposed to the barometric altimeter.

Thanks Day Hiker.

Day Hiker wrote:Also: I have a 60CSx, and when marking a waypoint, the unit uses the barometric altimeter, but when averaging a waypoint, the unit uses the GPS elevation. It comes in handy to know this if you want to choose which elevation to use. Your model may be similar.

No, they are not similar

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Day Hiker

 
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by Day Hiker » Thu Mar 11, 2010 5:34 pm

Diego Sahagún wrote:
Day Hiker wrote:Also: I have a 60CSx, and when marking a waypoint, the unit uses the barometric altimeter, but when averaging a waypoint, the unit uses the GPS elevation. It comes in handy to know this if you want to choose which elevation to use. Your model may be similar.

No, they are not similar


From looking at the eTrex owner's manuals from Garmin's site, I see a lot of screens and menu commands that are basically the same as those for the 60CSx. And both models have a barometric altimeter in addition to GPS, so there is the possibility that they both may operate similarly when recording waypoint elevations.

Neither the owner's manual for my 60CSx nor the owner's manual for the eTrex describe in enough detail the waypoint-averaging procedure to indicate that the GPS elevation is used when averaging a waypoint, while the barometric altimeter is used when simply marking one. But the 60CSx definitely does this.

This comes into play often when descending a canyon with poor GPS reception. The GPS elevation will be at the last place it had a 3D position, but the barometric altimeter will continue to read accurately, regardless of the satellite reception. So, if I have enough reception for a 2D position, I can mark the waypoint without using averaging, so it uses the barometric elevation (and the lat/lon from the satellites).

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by neghafi » Thu Mar 11, 2010 7:09 pm

I've also experienced such behavior with Garmin mobile XT installed on my smart-phone (I used my phone gps)
I was a bit more mixed.
I'd no topomap of the area on mapsource so I uploaded it in to google-earth and saw waw!
the track said that I've traversed across the peak to the other side!!!!!!
a part of a track was drifted !

- I was not in a canyon. The mountain wasn't that steep (at most 25 degree)
- I didn't use any auxiliary services for GPS
- I'd no battery problems
- My software (Garmin Mobile XT) was up to date.

After that I thought phone-GPS is not that relyable so bought a Colorado (to use google-earth overlay custom maps) and till now I haven't face with such a thing again


Anyway I feel my smart-phone locks faster than Colorado so I carry both of them.

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Diego Sahagún

 
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by Diego Sahagún » Fri Mar 12, 2010 12:38 am

Day Hiker wrote:
Diego Sahagún wrote:
Day Hiker wrote:Also: I have a 60CSx, and when marking a waypoint, the unit uses the barometric altimeter, but when averaging a waypoint, the unit uses the GPS elevation. It comes in handy to know this if you want to choose which elevation to use. Your model may be similar.

No, they are not similar


From looking at the eTrex owner's manuals from Garmin's site, I see a lot of screens and menu commands that are basically the same as those for the 60CSx. And both models have a barometric altimeter in addition to GPS, so there is the possibility that they both may operate similarly when recording waypoint elevations.

Neither the owner's manual for my 60CSx nor the owner's manual for the eTrex describe in enough detail the waypoint-averaging procedure to indicate that the GPS elevation is used when averaging a waypoint, while the barometric altimeter is used when simply marking one. But the 60CSx definitely does this.

This comes into play often when descending a canyon with poor GPS reception. The GPS elevation will be at the last place it had a 3D position, but the barometric altimeter will continue to read accurately, regardless of the satellite reception. So, if I have enough reception for a 2D position, I can mark the waypoint without using averaging, so it uses the barometric elevation (and the lat/lon from the satellites).

Serie GPSmap® 60 are more advanced than Serie eTrex mate. Anyway, I understand what you've said

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