Dnf's Is It Fact Or Bad Luck?

[+Roving Rangies]

This sounds strange, but Gary is doing a little thinking and has come up with a theory about DNF's. Well the caches that we have placed anyway.

 

If you have done one of our caches recently, can you please let us know the GPS that you were using.

 

Please we don't want lists of people that have not visited, just the ones that have whether they have found or not, logged the cache or not!

 

Little things please little minds, so please do not just look on, act today!

 

Vivien

Roving Rangies

[+Haggis Hunter]

Out of your 4 caches, you have 6 DNF logs, by 4 different cachers, all of which I can't say I have seen on the forums (may be wrong?). Would it not be better sending them a polite email asking them which GPS they use, as doing it on here, all you are going to probably get are the people who have found your caches.

 

I honestly don't think the different brands or models of a GPS are that much different on readings that they would cause people to say that they had bad coverage, perhaps it may be the hiding location, or even your co-ords that may require checking?

 

This is of course is just an open opinion, as I have not found any of your caches, and therefore can't honestly say why you have DNF's?

[+Roving Rangies]

Out of your 4 caches, you have 6 DNF logs, by 4 different cachers, all of which I can't say I have seen on the forums (may be wrong?). Would it not be better sending them a polite email asking them which GPS they use, as doing it on here, all you are going to probably get are the people who have found your caches.

 

I honestly don't think the different brands or models of a GPS are that much different on readings that they would cause people to say that they had bad coverage, perhaps it may be the hiding location, or even your co-ords that may require checking?

 

This is of course is just an open opinion, as I have not found any of your caches, and therefore can't honestly say why you have DNF's?

 

You are right of course. It was just that we returned to check our caches, and the co-ords are checked and are within 1-2 metres.

I have asked for the emails, and the first two I received (DNFs) were using eTrex legend C GPSs. This was what startd me off on my theory. I know it shouldn't be so..... I am hoping to meet the local users and see what their units say.

On the other hand, perhaps I should read up and see what the difference is between deg.min. and deg.min.secs and OSGB.

[+Lydford Locators]

Hi, Roving Rangies. Of your 4 caches, we were first to find on 2 of them. Home to Roost gave us a lot of problems, but we put it down to heavy tree cover. We had to resort to hopping over the barbed wire fence into the field, and approaching from several different directions. It probably took us half an hour to find. However, Come into the Garden Maude was much easier to find. Our GPS is the Garmin e-trex Legend. Now, we just need to find your other two caches . . .

[+Firth of Forth]

On the other hand, perhaps I should read up and see what the difference is between deg.min. and deg.min.secs and OSGB.

 

Therein could lie the problem..........

[+Haggis Hunter]

On the other hand, perhaps I should read up and see what the difference is between deg.min. and deg.min.secs and OSGB.

 

If I am not mistaken you have to do more than one thing on the etrex for chaning your co-ords from WGS84 to OSGB (vice versa), I have seen that if it isn't done correctly the co-ords could be out by 50 metres or more.

[+The Wombles]

I did a back-to-back comparison between five different models of GPS recently and was surprised by how much variation there was to start with. After a prolonged period of settling down, they still varied by significant amounts.

 

If you want to check the coordinates then ask visitors to post theirs by using the waypoint function on their found log. You'll soon see if there is much variation.

[+civilised]

I've found Roving Rangies co-ords to be very accurate - I'm using an Etrex Vista C.

 

However, their photos can be deceptive

 

civilised

[+Roving Rangies]

I did a back-to-back comparison between five different models of GPS recently and was surprised by how much variation there was to start with. After a prolonged period of settling down, they still varied by significant amounts.

 

If you want to check the coordinates then ask visitors to post theirs by using the waypoint function on their found log. You'll soon see if there is much variation.

 

This is useful info. We use a Magellan Meridian Colour. It defaults to Lat/Long in the format 51.21.256 001.32.333 (say), but it has a screen that shows the OSGB ref as well (which we don't quote).

It seems to reliably accurate to within 1 or 2 metres of our posted refs..

[+CrazyL200]

In a similar vein, 3 of us were out caching over the last 3 days - 4 different GPS units (3 garmins and a pda with a bluetoothed receiver), nearly every time we approached a cache we were looking in 3 slightly different places. Not far from each other, but enough to notice a difference. We also noticed that tree cover affected each of them differently, some times by as much as 5 or 6 metres.

[+Moote]

Observation

 

I was doing a cache once with Rutson, and decided just to go with his GPSr as I was being lazy and could not be bothered keying in the coordinates into my GPSr. Well we looked and looked for several minutes without success, I then decided that I would get the coordinates and key them in, after doing this I walk right up to the cache and retrieved it, there appeared to be about 30ft in difference in location. Now he has a Magellan and mine is a Garmin, and I know that the cache setters used a Garmin.

 

My conclusion was that both devices are only as accurate as the brand that set the cache i.e. The manufacturing inaccuracies in the calculations (rounding errors, algorithms etc) are reflected through that manufacturers range.

 

Not conclusive I know but interesting observation.

[+purple_pineapple]

On the other hand, perhaps I should read up and see what the difference is between deg.min. and deg.min.secs and OSGB.

 

If I am not mistaken you have to do more than one thing on the etrex for chaning your co-ords from WGS84 to OSGB (vice versa), I have seen that if it isn't done correctly the co-ords could be out by 50 metres or more.

 

in case anyone is interested, then it depends on the etrex - or rather its age. We bought our etrex last june, and it will convert in one step. Sister's is a bit older, and it won't. I believe it is is the software version its running. I don't know if this is upgradeable though!

[NickPick]

 

in case anyone is interested, then it depends on the etrex - or rather its age. We bought our etrex last june, and it will convert in one step. Sister's is a bit older, and it won't. I believe it is is the software version its running. I don't know if this is upgradeable though!

 

I bought my etrex yellow in 2001, and it converts in one step - When in OSGB mode, I can't set the map datum to anything else. It won't highlight that field.

 

The firmware is upgradeable - go to the Garmin download page to check your version. Mine's running version 2.20. Obviously, you need a serial cable to update it.

[+Alibags]

I agree with Moote. Many's the time I have been looking at my co-ords which say accuracy of 14 feet and the cache is some distance away. That's all very well, but we don't know what sort of reading the setter got. Whether they averaged it and double and tiple checked it. Mind you, if the arrow pointed right at the cache everytime I think it would be too easy.

 

I have also found that when caching with others with different brands and models of GPS, although they may have their own foibles, they all seem to be pretty much of a muchness. We may all go hacking off on different routes, but we all seem to end up at the same cache in the end!

[+Eco-sheep]

 

in case anyone is interested, then it depends on the etrex - or rather its age. We bought our etrex last june, and it will convert in one step. Sister's is a bit older, and it won't. I believe it is is the software version its running. I don't know if this is upgradeable though!

 

I bought my etrex yellow in 2001, and it converts in one step - When in OSGB mode, I can't set the map datum to anything else. It won't highlight that field.

 

The firmware is upgradeable - go to the Garmin download page to check your version. Mine's running version 2.20. Obviously, you need a serial cable to update it.

We use an Etrex yellow too. I'm on firmware version 3.3 now which Garmin list as the most recent. Interestingly I noticed in another thread (the "Which GPS" sticky) that somebody cites the ability to only hold one route in the memory at a time as being a major drawback with the Yellow. In fact mine has room for 20 routes, although I've only loaded one so far. I did wonder if this was something that had been upgraded in the newer firmware.

 

Take care,

 

Steve.

[+Brenin Tegeingl]

Yellow etrex's with v3 have a slightly different chipset to the older models with v2. This change was made to enable the yellow to receive and use WAAS. unfortunately those with v2 can not upgrade to v3, much to my annoyance .

 

Dave

[+kbootb]

Yellow etrex's with v3 have a slightly different chipset to the older models with v2. This change was made to enable the yellow to receive and use WAAS. unfortunately those with v2 can not upgrade to v3, much to my annoyance .

 

Dave

 

Same with my etrex summit. Version 2.50 I believe (writing this at a place where I don't have my GPS available ) so WAAS is not an option.

[+Eco-sheep]

Yellow etrex's with v3 have a slightly different chipset to the older models with v2. This change was made to enable the yellow to receive and use WAAS. unfortunately those with v2 can not upgrade to v3, much to my annoyance .

 

Dave

So presumably it's those older models that can only hold 1 route then, whereas the newer can hold 20?

[+Belplasca]

One thing that you should know about Magellan Meridians is that they tend to suffer from "GPS lag".

 

If I go marching up to a cache location, and stop when it says "zero ft", after a few minutes it will say that the cache is around 100 ft back the way I came...

 

So, these days, I tend to start looking for the likely hiding spot when I get to 100 ft from where the GPS first thinks the co-ords are...

 

Bob Aldridge

Edited March 2, 2006 by Belplasca