+Birders Posted January 25, 2006 Share Posted January 25, 2006 We've oft wondered why our very old Garmin GPS12XL appears to be so much more accurate than some modern devices for geocaching. Reading a review the other day Bren came across the term "Static Navigation", which appears to be a function of some GPS equipment which does not update the location frequently if the device is moving slowly. One quote said less than 4 kms/hour. This means that if your GPS is equipped for Static Navigation and you walk at slow speed the location updates will be slow. This accounts for a very noticeable difference between our GPS12XL and at least two modern devices. On occasions when we have been geocaching with friends using new gear, we have often had the situation where we have stopped to search for a cache but they have said "no, it's 20m further on". In each case we were right, although their GPS slowly caught up. Apparently the BT338 bluetooth GPS has the facility to switch this function off but we're curious to know if the latest handhelds have switchable Static Navigation as we've not seen the term mentioned in various specs.. Quote Link to comment
+walkergeoff and wife Posted January 25, 2006 Share Posted January 25, 2006 Interesting. I have noticed the same with my GPS12 (identical to the XL apart from the latter has an external aerial facility). I have been out with cachers who have had more up to date kit, but my GPS seemed more accurate. Maybe this is why? Quote Link to comment
Nediam Posted January 25, 2006 Share Posted January 25, 2006 we have often had the situation where we have stopped to search for a cache but they have said "no, it's 20m further on". In each case we were right, although their GPS slowly caught up I've had this with my PDA+GPS combo, although 20m seems a bit excessive (I think mines usually about 20-30 feet out). My "workaround" is to walk straight towards the cache at my usual walking pace, then stop when the "distance to go" reads about 25 feet. The GPS still counts down and usually ends up about 5 feet(ish) from the cache location. I figured it was due to the update speed of the card/PDA, but it's nice to know others have a similar issue. (I was planning on buying a second GPSr to check my other one out - don't think I'll bother now ) Quote Link to comment
Alan White Posted January 25, 2006 Share Posted January 25, 2006 It does seem to be the case that our Etrex's will take us past the location. The Mio168, however, seems to get it right first time. Solution: when you're within 20m stop and wait Quote Link to comment
+wildlifewriter Posted January 25, 2006 Share Posted January 25, 2006 Apparently the BT338 bluetooth GPS has the facility to switch this function off but we're curious to know if the latest handhelds have switchable Static Navigation as we've not seen the term mentioned in various specs.. If you asked Garmin this question* they would tell you that their "modern" range of handhelds don't need a user-configurable mode - because they handle it automatically. In a sense, this is true: the filtering and correction on these devices is very sophisticated these days. However, there's little doubt that compromises are made. I can see this quite clearly by comparing (walked) track logs from my iQue 3600 and (oldish) eTrex Vista, on the same route. Filering in the Vista is obviously optimised for low-speed work, whereas the iQue leans towards operation in a vehicle. The issue has re-surfaced because these new Sirf chipsets are so sensitive - allegedly - but in fact I believe that the different modes available are there so that OEMs can configure the chips for different applications. -Wlw. * In an ideal world. In the real world, it's almost impossible to get a sensible answer to such questions out of Garmin. Quote Link to comment
NickPick Posted January 25, 2006 Share Posted January 25, 2006 My Etrex seems to do this aswell. It also affects me when taking waypoints for a cache location, which I noticed the other day: I walked to the cache location, waited a few seconds, and marked a point, then I did another 4, all about 30 seconds apart (the time it took me to edit the names). When I plotted all the points on my GIS at work, it gave me 4 points in a dead straight line. I did the same on another day, which gave me a line in a different direction. The next visit, I waited 5 minutes before logging, and got a cluster of points. So I agree with Alan's solution. Does anyone know if you can turn this off on an etrex? Actually, I did read here a while ago that one cacher's solution is to run the last 50m to the cache - this keeps the speed above 4kmh. Sounds a bit energetic for me! Quote Link to comment
+The Bolas Heathens Posted January 25, 2006 Share Posted January 25, 2006 (edited) We get this on our eTrex too. Our solution is to stop about 20ft from the cache and let the GPS settle. We then sometimes switch it off and back on again so it re-aquires the satellites and gives us a fresh perspective that we can double check against the first reading. Of course, some caches are more obvious than others and can be spotted quite quickly when in the general vicinity of the cache site (tell tale pile of sticks for example). Edited January 25, 2006 by The Bolas Heathens Quote Link to comment
+walkergeoff and wife Posted January 25, 2006 Share Posted January 25, 2006 Are we talking about following the arrow, or actually looking at the co-ords displayed on the GPS? I always abandon the arrow if I don't spot the place immediately as its update rate is much slower than the co-ords readout. I often find that, using the co-ords readout and comparing them with what is given on the cache page, I can get within a few feet of the location, and often actually on top of it. Quote Link to comment
+Just Roger Posted January 25, 2006 Share Posted January 25, 2006 My Etrex (Venture) has something called Battery saver mode which, according to the manual 'reduces the rate of position updating'. I've never used this but is sounds rather like your Static navigation mode. I dont have a problem of overshoot with the Garmin but I do with my Magellan GPScompanion on my palm. I guess this is the same effect you are talking about. Quote Link to comment
+kewfriend Posted January 25, 2006 Share Posted January 25, 2006 Thanks for all that. Now I think I understand why the brand new Etrex my daughter got for Xmas is less capable than my old old GPSMAP12 from Garmin. The latter takes time to lock on but when its locked on its dead accurate. The former always seemed to be adrift on geo-hunts. Quote Link to comment
+Wadders Posted January 25, 2006 Share Posted January 25, 2006 Ok, I understand why you would want the static navigation, and handy it would be in some circumstances. However i would not want my GPS to be any more accurate than it is allready, i enjoy the final bit where you have to hunt around in perhaps a 15-30' radius looking for the cache. Can you imagine walking right to it every time?? Saying that, i sometimes feel a prat in a muggle type area, looking at my gps and having to walk around in circles Quote Link to comment
+Birders Posted January 25, 2006 Author Share Posted January 25, 2006 All interesting stuff, which reinforces our feeling to stick with our very old GPS12XL and not upgrade to newer devices. It just makes one wonder about claimed accuracy and makes a nonsense out of WAAS/EGNOS, at least sa far as geocaching is concerned. Quote Link to comment
+wildlifewriter Posted January 25, 2006 Share Posted January 25, 2006 It just makes one wonder about claimed accuracy and makes a nonsense out of WAAS/EGNOS, at least sa far as geocaching is concerned. Don't get carried away, now. Your conclusions about information displayed, while moving, don't have implications for the correct operation of the whole system. -Wlw Quote Link to comment
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