Digital compass accuracy

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Digital compass accuracy

Postby caver.adam » Mar 26, 2012 11:24 am

Ive been watching advances in digital compass technology and am wondering what would be considered accurate enough for cave surveying. I'm seeig some rather expensive units that work in any orientation with accuracy from 0.3 degree (TCM5 for $1500) to 1 degree (hmr3500 for $600). There are also plenty of tilt adjusted ones on the market much cheaper but they have limits of 40-80 degrees of tilt depending on the unit.

Ultimately I would like to combing a laser disto, accelerometer, and compass in one handheld unit. I know there are issues with compass calibration, but think its worth the time to work through those later.
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Re: Digital compass accuracy

Postby WVCaver2011 » Mar 26, 2012 12:03 pm

If I were you, I would just wait for the DXT model to come out. It looks like they are still making progress and it's just too late for the A3 model unless you are from the UK and can find a Disto A3 somewhere (like ebay.co.uk). Unless you have a friend in the U.S. who has an A3 to sell you, odds are you probably wont find an A3. Searching the web is worthless. Im just waiting on the DXT model because the A3 is out of stock and because I already have a DXT laying around.

It seems like those store models are much too pricey for what they do. Look around for a DUSI there are some of those floating around that people are willing to get rid of because for some reason or another they have problems calibrating them. I have one and havent had any significant problems with calibration. They're not a unit you'd want to buy if you were wanting to get within a degree of measurement consistantly but with two degrees it works pretty well. Just make sure you do front and back sights.

As far as the survey accuracy goes, the more accurate the better but most surveyors will go for a +/- 2 degree error. It really depends on if it's just being done for the hell of it (like out in the middle of no where) or may be associated with overlying homes, etc.
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