To relate our experience on the accuracy of devices, we've used both dedicated GPS devices and Smartphones alot in the course of building Walkhighlands. The site currently has 15,300km of walks on it, all of which have been recorded on the ground as GPS tracks by myself, Helen, Phil, Chris T (Southern Upland Way, Annandale Way), and a couple of others. The majority of these walks have been recorded on two GPS devices simultaneously, so that we get a track even if one device failed or there is some muck-up; in total we've got just under 28,000km of recorded GPS track data. This is enough for well over half way around the world
. Devices used are the Garmin GPS 60, Garmin Geko, Garmin Etrex, Garmin Etrex H, Satmap, Motorola Defy phone running Viewranger, Motorola Defy+ with VR, and HTC Desire with VR.
This amounts to a pretty extensive test, especially with alot of the tracks being pairs of duplicates recorded with different devices. The only conclusion on accuracy from all this is that older devices are less accurate on the hill than more recently launched ones (though all are accurate enough to be a very useful navigation aid). I beleive the difference is that the more recent devices have a H-GPS receiver (high sensitivity) which was lacking on the dedicated GPSs' of a few years back. The Garmin GPS60 (an old, chunky thing with a sticky-out aerial), Geko and the original generation Etrex are noticeably less accurate, and often go crazy in forestry or below steep crags. Recently we've been repeating quite a few routes which were recorded only on the older devices to improve accuracy. The most accurate devices have been the 3 types of smartphone, the Satmap (I only had it on trial and did have other issues with it, that I understand have been resolved) and the Etrex H. There is really nothing to choose between these devices on accuracy - the tracks are almost identical; in a pocket, I think the Defy just shades it against the Etrex H, though the latter matches up when strapped onto a rucksack lid. (I think the chip in the Defy may be the Broadcom BCM4750 which is the same chip as an iphone 4 - which I've never used - , but different to an iphone 3s and the earlier ones where there were complaints about GPS accuracy.)
Anyway, getting back to the topic:
I think everyone who has posted has agreed
that all hillwalkers (not everyone who uses the forum - some are heading for walks round Edinburgh
) should be carrying a map and compass, and have the skills to use them.
There's alot of good information on mountain navigation skills here; for those with basic map reading skills but who are not so confident with a map and compass when the clag is down, it's well worth reading the sections on relocation strategy, catching features, estimating distance, slope aspect, and aiming off, and practising. If unsure, consider going on a navigation course. We're hoping to publish a more detailed article specifically about the use of GPS and smartphone devices next week.
