Having a few GPSr problems.

[skzodiac]

Hey guys, I am extremely new to Geocaching and made my first attempt today, well 2 attempts with 1 succesful. I was smart enough to bring along 2 GPS units, just incase I was having some technical issues. I noticed that my older Eagle Explorer seems to be a little more accurate than my Lowrance iFinder Hunt-C. Does anyone know if there's some type of "Calibration" that I need to do? It seemed to always put me about 10 yds away southwest of where I was, but the older Eagle put me within about 6 feet of where I actually was. If the unit is messed up, that doesn't really bother me much since I get all my units from my uncle who works at Lowrance here in Tulsa, but I want to make sure there isn't something I can do to try and resolve it.

 

I also noticed that every now and then it would kind of jitter and jump from place to place even if I wasn't moving, so I don't know if its a hardware thing or some kind of weird user error.

 

Thanks!

[+unicyclist]

Here is how I look at it. Every GPS is accurate to withing 12 feet IF the satilite signals are good, and your GPS has fresh batteries.

 

If the cache hider and you both had fresh batteries and strong great satilite signals, it still can put you at 24 feet away.

 

2 GPS's can both be 12 feet off putting you 24 feet off.

 

All that above was if everything was perfect. What if the skys are cloudy, dark, and one of yall (the hider and finder) have low batteries. Things can be WAY OFF.

 

Basic advice I have heard on the forums (which I know follow) is when you get within 50 feet, put the GPS away and look for where YOU would hide a container.

 

EDIT: (joke) You would walk up to the exact place if you had a Magellan

Edited October 15, 2006 by unicyclist

[+hikergps]

Sounds like your datum on the Lowrance is set to NAD83, instead of WGS84. I had a similar issue last cache I looked for. I was cussing the cache hider until I remembered that I had changed to datum to NAD83 for a mapping project. As soon as I set it back to WGS84 I was right on top of the cache. Before I was about 30ft to the SW. Double check your datum settings.

[andman]

Here is how I look at it. Every GPS is accurate to withing 12 feet IF the satilite signals are good, and your GPS has fresh batteries.

 

If the cache hider and you both had fresh batteries and strong great satilite signals, it still can put you at 24 feet away.

[im]http://i106.photobucket.com/albums/m263/geounicyclist/121224.jpg[/img]

 

2 GPS's can both be 12 feet off putting you 24 feet off.

 

All that above was if everything was perfect. What if the skys are cloudy, dark, and one of yall (the hider and finder) have low batteries. Things can be WAY OFF.

 

Basic advice I have heard on the forums (which I know follow) is when you get within 50 feet, put the GPS away and look for where YOU would hide a container.

 

EDIT: (joke) You would walk up to the exact place if you had a Magellan

We all know that clouds and darkness (WTF??) do not effect your GPS, so that part of your post is dead wrong. What I am wondering about is the battery part of it. Is a GPS going to be more accurate when it's batteries are at 90% than when it's batteries are at 45%?

[+hukilaulau]

 

EDIT: (joke) You would walk up to the exact place if you had a Magellan

I started caching with an eXplorist 200. usually walked up to the exact place. Then I "upgraded" to a Garmin. Now, on a tough cache where the Garmin is spinning like a top, I transfer the coords into the eXplorist, and walk right up to the exact spot.

[+briansnat]

moving to appropriate forum

[ossumguywill]

EDIT: (joke) You would walk up to the exact place if you had a Magellan

 

Magellan is way more accurate in my expirience. I do not understand why this would be a joke, seeing as a standard explorist is 14 channel and WAAS enabled while a standard garmin is 12 channel and not WAAS enabled. I went caching with my 600 and my friend's 60CSx. The magelland got me right on top of the cache, and the 60CSx had me about 10 feet off.

[andman]

EDIT: (joke) You would walk up to the exact place if you had a Magellan

 

Magellan is way more accurate in my expirience. I do not understand why this would be a joke, seeing as a standard explorist is 14 channel and WAAS enabled while a standard garmin is 12 channel and not WAAS enabled. I went caching with my 600 and my friend's 60CSx. The magelland got me right on top of the cache, and the 60CSx had me about 10 feet off.

I don't know what you mean by a "standard" Garmin not being WAAS enabled?

 

You then went on to mention a 60CSx which is surely WAAS enabled (as most Garmin GPSr's are).

 

As for 14 vs 12 channels, what the use of having more when most people are only receiving 8-11 channels max?

 

As for your little experience with your friend, are you really trying to put the Garmin down for being 10 foot from perfect? Ten foot is great, this is the first time I've seen someone complain about it. As for the Mag being spot on, that's great as well, but chances are that on the next cache the Garmin will be close while the Mag is a couple feet further away. Judging units by one single benchmark is not telling at all.

 

Both are great units, both companies have advantages and disadvantages. However, your reasons don't compare either in any type of solid fashion.

[+hogrod]

Sounds like your datum on the Lowrance is set to NAD83, instead of WGS84. I had a similar issue last cache I looked for. I was cussing the cache hider until I remembered that I had changed to datum to NAD83 for a mapping project. As soon as I set it back to WGS84 I was right on top of the cache. Before I was about 30ft to the SW. Double check your datum settings.

 

I bet the OP could care less about the Garmin/magellan debate going on in this thread since he owns a lowrance & thats what his question was about. Sticking with the OP question, I agree with hikerGPS, sounds like the datum is set wrong.

[ossumguywill]

EDIT: (joke) You would walk up to the exact place if you had a Magellan

 

Magellan is way more accurate in my expirience. I do not understand why this would be a joke, seeing as a standard explorist is 14 channel and WAAS enabled while a standard garmin is 12 channel and not WAAS enabled. I went caching with my 600 and my friend's 60CSx. The magelland got me right on top of the cache, and the 60CSx had me about 10 feet off.

I don't know what you mean by a "standard" Garmin not being WAAS enabled?

 

You then went on to mention a 60CSx which is surely WAAS enabled (as most Garmin GPSr's are).

 

As for 14 vs 12 channels, what the use of having more when most people are only receiving 8-11 channels max?

 

As for your little experience with your friend, are you really trying to put the Garmin down for being 10 foot from perfect? Ten foot is great, this is the first time I've seen someone complain about it. As for the Mag being spot on, that's great as well, but chances are that on the next cache the Garmin will be close while the Mag is a couple feet further away. Judging units by one single benchmark is not telling at all.

 

Both are great units, both companies have advantages and disadvantages. However, your reasons don't compare either in any type of solid fashion.

 

Sorry, what I mean is that being WAAS enabled is not something that garmin thinks is essential. I am aware that the 60CSx wis WAAS enabled, I was just stating that my explorist was more accurate (this is probably because of TrueFix). Where I live, 10 feet can be essential in accuracy for geocaching and I also use my unit for surveys. All I ment was that in my expirience magellan units are more accurate, so the joke about getting closer with the magellan is actually a valid statement.

Edited October 15, 2006 by ossumguywill

[skzodiac]

Sounds like your datum on the Lowrance is set to NAD83, instead of WGS84. I had a similar issue last cache I looked for. I was cussing the cache hider until I remembered that I had changed to datum to NAD83 for a mapping project. As soon as I set it back to WGS84 I was right on top of the cache. Before I was about 30ft to the SW. Double check your datum settings.

 

I bet the OP could care less about the Garmin/magellan debate going on in this thread since he owns a lowrance & thats what his question was about. Sticking with the OP question, I agree with hikerGPS, sounds like the datum is set wrong.

 

I don't care much about the Garmin/Magellan debate, but it was interesting to see different views.

 

Anyway, back to the original subject, I checked the datum selection, and you two were correct. It was set on NAD83, set it back to WGS84 and it's back on track, it also quit jittering around after I set it back.

 

Thanks for the help! Didn't want to have to call my uncle and get the 45 minute lecture on the unit (he can turn a yes or no question into a 3 hour debate).

 

Thanks for the help!

[Grasscatcher]

The problem was the difference between NAD 83 and WGS 84? Wrong!

I won't argue, but to prove it to yourself, select one of your waypoints saved in your GPSr. With the GPSr set on WGS 84,write down the coordinates. Now change the GPSr to NAD 83 and select the same waypoint and compare the coordinate numbers.

 

Maybe between NAD27 and NAD 83/WGS 84, but not between NAD83 and WGS 84. Those two are so close to being identical that they are generally interchangeable.

Edited October 16, 2006 by Grasscatcher

[skzodiac]

The problem was the difference between NAD 83 and WGS 84? Wrong!

I won't argue, but to prove it to yourself, select one of your waypoints saved in your GPSr. With the GPSr set on WGS 84,write down the coordinates. Now change the GPSr to NAD 83 and select the same waypoint and compare the coordinate numbers.

 

Maybe between NAD27 and NAD 83/WGS 84, but not between NAD83 and WGS 84. Those two are so close to being identical that they are generally interchangeable.

 

I changed those and that fixed it, so I don't know. It may have just been something screwed up in datum for the NAD set, but either way it's operating normal now.

[+GClouse]

We all know that clouds and darkness (WTF??) do not effect your GPS, so that part of your post is dead wrong. What I am wondering about is the battery part of it. Is a GPS going to be more accurate when it's batteries are at 90% than when it's batteries are at 45%?

 

Actually cloud cover can degrade the satellite signal enough that some older less sensitive GPSr models may not be usable. Darkness actually doesn't affect the reception, but around the time of the vernal and autumn equinoxes when the sun is just below the horizon (just before sunrise and just after sunset), there is a sort of RF refraction effect that produces a lot of uhf and microwave interference. The is due to the fact that the sun produces a lot of RF radiation as well as light.

 

WAAS improves accuracy by calculating an error correction bases on location readings at reference ground stations and relaying the error data to WAAS enabled receivers. WAAS improves accuracy most of the time, but localized weather conditions can cause signal distortions that the WAAS will not compensate for, unless you are close a WAAS ground station and therefore under similar weather conditions.

 

And before someone points out that radio waves travel at the speed of light which is a constant, please note that the speed of is a constant in a vacuum. Transparent materials (such as air) slow the propagation speeds according to density of the material.

Edited October 23, 2006 by GClouse