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Altimeter Feature


rserkes
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I'm new to this geocaching experience and need to ask some VERY basic questions. One of the features I want in a GPS is the ability to know my altitude. Some units specify they come with a barometric altimeter. Others don't have it. The ones that do are considerably more expensive. Will an entry level GPS (e.g., Magellan SporTrak) give me my altitude or do I need a unit with the barometric altimeter built in?

 

Also, I want to know the total distance traveled at the end of my day. I like to hike and keeping tabs of total distance is important to me. Do the entry level GPS untis have this feature?

 

What GPS would you recommend for a beginner who wants the above features for less than $200?

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There are some differences between altimeters. There are the barometric altimeters, that are only in some units, that tell the altimeter by the barometric pressure. The other units, like the SporTrak, will tell you your altitude by using sattelites. It triangulates you (or something like that) and gives you a rough altitude. When the barometric altimeter is calibrated, I think It's supposed to be more accurate, however, I have heard they can be a pain in the a**, and sometimes constantly need calibrating (I have never used one though, so I am not sure).

 

The distance traveled is no big deal. Many low end GPS units have odometers. The SporTraks do. I have a SporTrak Map, and a Meridian Gold. I would reccomend the Meridian Gold if you are looking at Magellans. I like mine a lot. I don't think the Magellans have barometric altimeters however. Even the Meridian Platinum which has a magnetic compass, only has a barometer, and little weather station, but no altimeter.

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Sure thing. The main difference between the Meridian Gold and the Sportraks are the SD cards. It's very nice to be able to load a lot of Topo or street maps into the unit. If you are not concerned with this though, it wouldnt make a difference. The screen a resolution on the meridians are nicer, but the Sportrak is very useable. I really like my sportrak, but I dont really use it anymore, due to the MeriGold. If you are looking at the basic SporTrak Yellow, make sure it has everything I said it does. Most of what I said is based on the SporTrak Map, as that is the one I have. I would also recommend it over the basic one, as it is cool to have some space to load Topo maps in.

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Hi,

 

For around $200 I have to agree that the Gold Meridian is a excellent choice. I had a Garmin with the patch antenna (A Etrex Legend) and while it was a nice unit, it's performance geocaching in canyons and tree cover was less than what I liked.

 

I sold it and got a Magellan Meridian and just amazing the performance difference. :mad: Plus the SD cards with the Mapsoftware is very nice.

 

I just got a Garmin 60c and it's performance is just as good as the Gold. I'm trying to decide which to keep right now... The Magellan is built better IMO though, the screen is better protected and the handstrap is attached much better. The Garmins (both my older one and this new one) is just held with a small piece of plastic... Performance is the same between them (though the Garmin is MUCH faster on startup!! <_<

 

Take care, Bill

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Not to rain on your parade or anything. But I figured I should at least mention the problem with the SporTrak's stress cracks. It doesnt happen to all of them, but it did to mine. I sent it back in, and everything is fine now. Search the forums for "stress cracks" and you should find a very thorough thread that discusses the problem. Other than that, they are great units. But overall, I would recommend the Meridian, for the price.

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I had originally considered a couple of Garmin receivers because of their barometric altimeters. As SBPhishy mentioned, though, I've been reading that they can be a little difficult to calibrate, etc. and I finally decided that GPS altitude would work just fine for my recreational purposes. I figure that the 23MB of available memory in the SporTrak Pro will be more than enough for my current needs, and I liked the fact that there's an optional neoprene case in which the receiver can be used.

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I'm new to this geocaching experience and need to ask some VERY basic questions. One of the features I want in a GPS is the ability to know my altitude. Some units specify they come with a barometric altimeter. Others don't have it. The ones that do are considerably more expensive. Will an entry level GPS (e.g., Magellan SporTrak) give me my altitude or do I need a unit with the barometric altimeter built in?

 

Also, I want to know the total distance traveled at the end of my day. I like to hike and keeping tabs of total distance is important to me. Do the entry level GPS untis have this feature?

 

What GPS would you recommend for a beginner who wants the above features for less than $200?

First of all yes the Magellan SportTrak Map or Pro will do all you are asking for. Second, do not rely on the altitude from a GPSr for accuracy. Magellan has told me themself that there can be as much as 30 meters difference between real and shown. They aren't made for vertical as they are made for horizontal measurements....

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I use a Magellan 330. Altitude is measured per satellites, not barometric.

On barometric vs satellite triangulation:

 

I would think that almost all GPS systems (with altitude) use the satellites. To my mind this is more accurate. If, as stated, there is a possible 30' error, that stills puts you within 80' contour lines, which is fairly standard.

Barometric readings are based on air pressure. Less air pressure as you rise in altitude. However, this pressure is also affected by heat/cold and weather. Thus even setting your barometric altimeter at the start of a hike (sunny day) - it may not be accurate at an altitude later in the day and up the mountain when clouds and rain and cold move in. Or, vice versa.

The barometric altimeters I have used, I have found to be finicky in regards to this. I would much more trust my GPS.

That said, altitude is only ONE factor in navigation. I always cross reference with a map.

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Being an owner of two GPS units, one with barometric altimeter, the other without, I can tell you that both will tell you the altitude.

But the one with barometric altimeter does a better job. You can actually have the best of two worlds, since the barometric sensor will keep track of short-time altitude changes with better accuracy, while the unit can be set to re-calibrate according to the GPS altitude automatically. Thus, the spurious effects that happen with GPS altitude, during more difficult reception conditions, are smoothed out by the barometric altimeter, while the long-time effects of changing air pressure, due to weather-changes, are eliminated by the auto-calibration.

 

Besides, if I start from home, I always calibrate to the known location of my back yard first. Right now, we have a really sturdy high-pressure weather here, and yesterday, my altimeter converted that pressure to -42 m around the house. The correct figure is 130 m. So either just key that in, or wait for the auto-calibration to fix it automatically.

 

Also, units with barometric altimeters usually have more software built-in, like the ability to show elevation plots over time and distance.

 

My units are the Garmin eTrex Vista and the iQue.

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One other way to estimate/verify your altitude:

 

I have a Meridian with Mapsend Topo. When on the map page, if you move your cursor to an empty spot next to your current position, it will show you the altitude based on the topo map loaded in the unit.

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Being a pilot, I know that air pressure at any given altitude will change with weather. That's why altimeters in airplanes have an adjustment dial. When you are flying past, or landing at an airport, you call them on the radio and ask for a setting. They will tell you what the current barometric setting is so you can adjust your altimeter to the correct barometric pressure.

 

I would be very sceptical of a barometric altimeter if I had adjusted it more than a couple hours ago, and more than 1000' in altitude ago...

 

I have heard the satellite triangulation method in GPSrs is 50% less accurate than the horizontal accuracies. i.e. if your GPS is reporting a 30' EPE, then the altitude could be off by 45'.

 

Also, I would recommend getting a Magellan Meridian over a sportrak, for two reasons.

 

1) The Meridian doesn't have the stress crack like the Sportrak

2) The Meridian can use SD cards

 

If you get a Meridian, get at least the Gold. If you want a barometer & thermometer, get the platinum. You can get them used or a "new" store demo for just over $200. Paid $209 for mine on eBay.

 

 

Edutid fer speling

Edited by ckhd
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If you get a Meridian, get at least the Gold. If you want a barometer & thermometer, get the platinum. You can get them used or a "new" store demo for just over $200. Paid $209 for mine on eBay.

 

I totally agree that you should at least get the Gold (thats what I have). Just to clarify though, the Platinum has a barometer, but not a barometric altimeter.

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