14

Our analog altimeter, which we had had for over 20 years, was stolen this summer. We are now faced with a choice between digital or analog altimeters.

What are pros and cons between the two? (e.g., reliability, accuracy, sensitivity, ease of use while backpacking) Are there any other devices that can tell us our altitude and the number of vertical feet we have hiked since we last stopped to breathe?

Improve this question
4
  • Are you talking about pure barometric devices (not GPS or hybrids that use both a barometer and GPS)? I don't see any reason to care about whether the readout is digital or analog. It just seems like a matter of personal preference.
    – user2169
    Commented Sep 20, 2015 at 20:21
  • Pure barometric device -- I'd like it to be as uncluttered and non-clunky as possible. Many details of my preferences were in my original post, which was closed as asking for shopping advice. So your comment is that there is no objective criterion by which to choose digital over analog or vice versa? What about sensitivity ... I want 20 feet sensitivity; the old altimeter had 20 foot divisions, and one could interpolate (without great confidence) to 10 feet. Lag time? The old analog altimeter was a little sticky.
    – ab2
    Commented Sep 20, 2015 at 22:42
  • They have a app for that.
    – ShemSeger
    Commented Sep 21, 2015 at 0:32
  • @ab2: Some Barometric watches will measure to 1 meter resolution (e.g. Suunto), so you can get a digital meter that meets your stated requirements.
    – user5330
    Commented Sep 21, 2015 at 5:28

3 Answers 3

Reset to default
5

I just spent 8 days in the Colorado backcountry at the beginning of this month and had a similar question before leaving for that trip. Here's what I did...

  1. I looked at a full-featured GPS unit (Garmin, et al), but I did not want to carry the extra batteries needed to power it for that long.
  2. I also looked at the Suunto watches and a few similar full-featured, premium watches, but the price range was too steep and there was still the question of battery life.
  3. I checked into using an analog altimeter, but for the same weight, less cost, and smaller size...
  4. I ultimately purchased a Casio digital altimeter/barometer watch

The model I purchased was accurate to within 20 feet (6 meters), and was very easy to calibrate at the trailhead. Refresh rate on the display was less than 5 minutes, which was more than adequate for the pace I was moving around at.

One thing I had to pay attention to was when the weather would change... my altimeter readings would shift a little (20 to 60 feet, or 6 to 18 meters) with low pressure systems, but they would return to baseline once the weather stabilized. Never caused a problem, but it was something to watch out for.

Improve this answer
1
  • 1
    Those watches simply corelate the altitude with the air pressure, so it only measures the pressure and calculates the height difference. As often as possible during your trip you should calibrate it therefore. A nice side effect is you are able to notice possible weather changes when you e.g. KNOW the shown altitude is too low, the weather possibly gets better.
    – Wills
    Commented Sep 22, 2015 at 16:08
7

I think the biggest difference between the two is going to be batteries, but digital altimeters are going to come with a lot of fun features like tracking your elevation ascent and descent rates, and warning you when a potential storm is rolling in.

What a lot of alpinists carry with them for calculating altitude in the back country these days is a watch with a altimeter.

Example of a digital watch with altimeter functionality

Barometric altimeters are more accurate for calculating exact elevation, but unless you're a cartographer then I don't think it's really necessity to know your elevation accurate to +/-1m. Lots of people just use their GPS device, what precision you get will depend on the quality of your device, how fine a reading it's capable of taking, and what angle the satellites are to the horizon, but the accuracy is typically between +/- 5m and 15m. If you're like me, and don't necessarily need to know an uber-accurate elevation, then you'll probably be happy just using the GPS in your smart phone. I suggest you get a backcountry navigation app that also tells you your altitude. I recommend you try out Backcountry Navigator before you spend big money on a new altimeter or GPS. I'm pretty satisfied with it, and it does a lot more than just tell you your elevation, it also shows you where in the world you are on a topographical map, maps your trail, and lets you set waypoints with pictures or selfies attached to them.

Improve this answer
8
  • 2
    -1: "GPS devices are far more accurate for calculating altitude" is just wrong. The GPS altitude you refer to is GPS location supplemented with map elevation data, likely on relatively flat terrain. Barometric Pressure is still used by Pilots, parachutists, para-gliders and climbers for a good reason
    – user5330
    Commented Sep 21, 2015 at 5:22
  • @mattnz Well then I'm going to have to ask my civil engineer father-in-law what that do-hicky was called that he was using to find exactly where 4ft above the water table was on his farm yesterday. I thought I heard him say he was going out to take some GPS readings, but I won't say that I can't be wrong. I stand corrected on GPS vs Baro-altimeters though, I've edited my answer.
    – ShemSeger
    Commented Sep 21, 2015 at 6:07
  • 1
    @mattnz, your comment is a bit misleading/might be misinterpreted. GPS devices don't need elevation data. Yes, many devices will use them to show better results. And yes, they're not too accurate: Generally, Altitude error is specified to be 1.5 x Horizontal error specification.
    – Roflo
    Commented Sep 21, 2015 at 15:20
  • 2
    goes on to say... "+/-23meters (75ft) with a DOP of 1 for 95% confidence." - so 5% of the time the error is greater then 23 meters. Also most (not all) GPSs give height with respect to WGS84 ellipsoid and this can differ by up to 100m (70 is common) from the geoid(model for mean sea level). As most consumers have no idea what model their GPS is using for height, GPS altitude error can be as high as 100 meters and be within the "95% confidence"
    – user5330
    Commented Sep 21, 2015 at 22:26
  • 1
    @ShemSeger - many GPS devices have built-in barometric altimeters to improve the GPS accuracy for elevation. Both 'sensors' get used together.
    – Roddy
    Commented Dec 21, 2015 at 21:41
3

One 'pro' of certain digital altimeters: Even without GPS they can do a surprisingly good job of distinguishing between changes of elevation and changes of 'atmospheric pressure'. This means that you don't need to reset the altimeter to known elevations so frequently.

The Suunto Core has this feature. It works by looking at the rate of change of pressure. If the rate is slow, it assumes it's just changes in the weather, and that the wearer isn't going anywhere - Barometer mode. If the rate of change is higher, it switches into Altimeter mode, and assumes that atmospheric pressure isn't changing.

It's not perfect. If you're trekking over very gently-angled paths all day it would stay in barometer mode unless manually switched - and once in Altimeter mode, any weather changes will still affect the altitude reading (like a conventional altimeter).

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.