 Barking, I am scrabbling a bit here (it is a long time since I did any reaserch on the subject) But I think that accuracy is some sort of rms value so you will get >25m 99% of the time, >20m 95%, >10m 90%, 2m 85% for example. If I can't see within the accuracy of a GPS then I am probably in a little trouble. When using them on the sea, the charts are often more inaccurate than the GPS. The whole lot has to tie up. My various units display a remarkable accuracy most of the time, on my bike 705 for example you can see which side of the road I was on and where I swerved around potholes! Steve D
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 That is basically what I said... for walking / most other outdoor persuits a vertical accuracy of ~5-10m should be more than enough - I suppose if you were a climber then it is more of an issue? In my original post was just trying to explain why the indicated altitude on some altimeters will vary even though you have not moved. For some of the time the accuracy will be better - at other times it will be worse - the point was it varies and so the reading at a fixed spot will also vary. Your Garmin 60CX (that 'yoda' was using) supports DGPS for increased accuracy (quite a lot do not) - if you look at the satellite screen it usually puts a 'D' over the signal bars if a differential signal is available - think mine also estimates the 'accuracy'.
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| Edited: 18/03/10 12:56 |
 WAAS (Wide Area Augmentation System) is only in the USA/Canada but there is a European version EGNOS (European Geostationary Navigation Overlay Service) which does the same thing. As Steve says the vertical accuracy of GPS (VDOP) is less accurate than the horizontal position (HDOP) because you do not get the same descrimination between the satellites and receiver in the vertical plane so it is more difficult to tie in the receivers altitude accurately. Anyway back to the original thread anyone got a good word to say about Suunto watches? My Protrek gave up the ghost a fortnight ago (my fault, was excellent for a very long time). I'd like a replacement that does altitude and has a HRM, not so interested in a GPS ot compass, suggestions?
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| Edited: 18/03/10 13:31 |
When I said my Suunto Core increased in Altitude whilst standing still, it gained about 400metres of height in about 3 minutes while I stopped and had a drink. This was due I decided to blocked atomspheric holes. We have a nokia 5800 with viewranger. It has a not very accurate altitude function. What I liked about the Core was it was always on. Whilst on a long trip we do not keep our 5800 on due to wearing out batteries. for example our next trip camping away from everthing in the Atlas mountains with 3 spare nokia batteries that have to last. An always on altimeter would be useful. Now I do not like Suunto I wonder what my solution is?
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 they seem to incur a fair bit of user error destruction. i assume that the altimeter holes are in the back of the watch so that swinging your arm doesn't change the air pressure and hence altitude. they seem far more trouble than they're worth. and something that's puzzled me, why do you need such accurate altitude readings? surely 10-20m is more than enough? even when climbing.
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The holes are in the back of the watch almost against your skin in the bottom of a shallow U shaped, in plan and section, trench that leads to an edge of the watch. I would be quite happy with 10 to 20 m accuracy if I could have faith in it.
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still doesn't mean they're not there to avoid arm swinging pressure changes i.e. designed to be there. perhaps this instrument should be raised under the gimmicky crap thread instead - seems to be the best place for it.
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Dereck I use a powermonkey with a solar panel thing for topping up my phone (and in fact, my mp3 and Garmin 705). The powermonkey will charge my phone 3 times, the gps twice and the mp3 player forever. The solar panel keeps the PM topped up. On my bike it sits on the rear rack soaking up a few rays, on my kayak it lives in a clear bag on the back deck and on my pack sits on top attached to the crampon attachments. On short trips I don't bother with the solar panel. Steve D
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Hi Steve, I have always thought that solar panels were at this point: untried, heavy, vulnerable and did not charge in my normal walking area Scotland where rainpower has the most potential. This power monkey, has its own battery and a solar panel and suitable adaptors to a nokia phone? How much does it cost and weigh and how long have you had it without damage or corrosion making failed contacts? Have you had it working in Such places as Scotland for weeks on end? Is there a reliable panel that charges the phone battery directly to save weight?
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If you'd have put the seal back in it would have ben fine. If you buy a genuine suunto battery replacement kit it comes with a new seal as well. When I saw this threads title I thought "I know what this is about" and thought it would be a warning not to use strong deet whilst wearing one. Last year I was ont he West Coast of Scotland, smothered myself in 98% deet and 5 m inutes later there was black plastic all over me and my clothes - the plastic back of the watch was melting.
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 Doesn't DEET melt most things?  In defense of Suunto watches - I have a Suunto Observer - had it for 7-8 years - no problems. Replaced the battery 3 times in that period - cost approx £6 (Battery + seal) each time. Hardly a huge expense! I find the altimeter very useful for quick navigation - e.g. on long ascent in cloud - am I near the top? Check watch - 50m ascent to go etc. I calibrate the altitude at the start of a walk - either from a known height from OS map - or from GPS. Not normally more than 10m out by the end of the day. Also very useful as additional bit of navigation info in addition to map/compass (I am glossing over the fact I could use the GPS for that) However the temperature display is a useless feature (I know it uses it internally for the barometer) unless you are interested in the temperature somewhere between ambient and body about 5mm from your wrist, and the alarm is slightly quieter than silent! Finally - Parky - why do you need such accurate altitude readings? Need? lol Altimeter Watch=gadget=toy I needed an 'outdoor' watch for the same reason as I needed multiple tents, GPSs, stoves, coats, shoes.... even maps and compasses - navigate by stars and sun anyone?
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lol rob. ah! now i understand. all this altitude nonsense is strange illogical justification for "toy! gimme, gimme" if people were only just honest with themselves... (strokes satmap and camera)
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 I have a Suunto Vector which I was given as a pressie; do other people find that it's best to keep an eye on the altimeter function, and check it now and again against known heights such as a trig point, re-setting it as appropriate if needed? There have been times when I know it's accurate when I set off, but gets less and less accurate as the day goes on.
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why do you need to know your altitude with such precision? they should be set regularly throughout the day at known points - which the only way to be absolutely accurate will be at a trig point - if you can find one. the only thing i can think of where it is useful is if you are climbing. otherwise it's yep, i'm here.
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Hi Steve, I have always thought that solar panels were at this point: untried, heavy, vulnerable and did not charge in my normal walking area Scotland where rainpower has the most potential. This power monkey, has its own battery and a solar panel and suitable adaptors to a nokia phone? How much does it cost and weigh and how long have you had it without damage or corrosion making failed contacts? Have you had it working in Such places as Scotland for weeks on end? Is there a reliable panel that charges the phone battery directly to save weight?
The beauty of the PM is that you can charge it from almost anything, Mains, car, laptop, or the panel. The solar panel it comes with is pretty robust and sits outside most of the time topping up the PM, the PM comes with adaptors for pretty much everything. I've not used it long term in Scotland but it has worked well on Cycling trips and Kayak trips. On the kayak I put the whole thing in a clear bag. It reduces the efficiency a bit but still keeps it topped up. The other thing is that if your phone is flat and you need it in an emergency, you can just plug in the PM and use it, a direct solar panel wouldn't manage that unless it was one of the larger ones and of course a solar panel won't help at night. My main reason for going for it was to keep my Garmin 705 running on longer cycle trips spare batteries is not an option with that. Google a price I've had mine for a while so prices will have changed. Steve D
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