Garmin GPS question

[zwvirtual]

I was looking at the Garmin HCX GPS and noticed that there's a Garmin Vista HCX and a Garmin Legend HCX. Can anyone tell me which is the better of the two, and why?

Edited December 1, 2009 by zwvirtual

[NordicMan]

Yep they're pretty much the same except the Vista HCx has a built-in magnetic compass and a barometric altimeter. Otherwise, identical

 

Next question probably will be.. is the compass & altimeter worth the extra $'s? Personally I say yes the magnetic COMPASS is worth having but not so much for the altimeter.

[Chrome Sushi]

I bought the Vista and honestly I don't use the compass or altimeter that much

[zwvirtual]

Here's another question: Why would the barometric altimeter even be needed if gps can determine altitude from the satellite readings?

[NordicMan]

The barometric altimeter is much more accurate than if just determining altitude via satellite triangulation. Altitude has always been the toughest value for a GPSr to derive.

 

Technically the GPSr doesn't even need the magnetic compass because it can determine compass bearing all by itself, but only when you're moving. That's why I DO like the magnetic compass when Geocaching. I can stand in one spot and the thing still knows where North is

[+Chrysalides]

The barometric altimeter is much more accurate than if just determining altitude via satellite triangulation. Altitude has always been the toughest value for a GPSr to derive.

I've always wondered - wouldn't a barometric barometer be accurate only if:

 

1. Air pressure remains static

 

2. You calibrate it to a known elevation

 

How do you calibrate it? How accurate is it compared to the GPSr calculation?

[+twolpert]

Once calibrated, it is more accurate than the GPSr itself. That's why it's there. But it's only as accurate as your calibration method. I don't know anything about the Vista HCX specifically. But in general, units with altimeters allow you to calibrate them to a known pressure or a known altitude. Or you can put them in "automatic" mode which means that they start with the GPSr altitude. In the latter case, it's really only good for measuring change in altitude, not absolute altitude (since the starting point is only as good as the GPSr, which isn't very good).

 

Some units (again, don't know about the Vista HCx) also allow you to record pressure trends while the unit is "off". Some hard-core backcountry types use this feature overnight to watch for ambient pressure changes which might mean changes in the weather.