Accuracy, GPS Receivers, and Newbies. :-)

[+schwachs]

Hi all... I've just discovered the world of Geocaching and am quite excited about the possibilities it offers for outdoor activities for me and my sons (7 & 5 years old).

 

We did our first search (and eventual) find with the use of my iPhone 3G and found the GPS in it a bit frustrating. At times it said we were 17 feet away but the margin of error was 54 feet... we'd then walk about 10 feet and be 60ft away, etc. etc... anyway, I think you get the picture. Is this standard for all GPS receivers when you get to the walking around stage or should I be able to get within a x # of feet radius without it moving around?

 

We eventually stumbled upon the location after giving up which of course turned the entire activity into a big win.

 

I am optimistic that this will be continue to be a great activity for the boys and me but I would like to upgrade my equipment but I want to make sure that the upgrade will provide some more accuracy. I'm not expecting pin-point accuracy but is it reasonable to expect to get within a 15' radius or something to that effect?

 

The handhelds I'm looking at are Garmin 60CSx vs DeLorme PN-40. I am happy to still use my iPhone & the Geocaching.com app for looking up caches but I am hoping one of the above two units will help with the accuracy.

 

I welcome any comments.

 

-- Joshua

 

ps: I also noticed the 60CSx is down to 261$ shipped. http://www.amazon.com/exec/obidos/ASIN/B000CSOXTO/02-4686-20 if that is of interest.

Edited December 15, 2008 by schwachs

[+ladyleo191]

Joshua, no GPSr is going to be 100% accurate all the time. You have to take into account the satellites, clouds, trees, all those things.

 

In addition, you have to take into account that the cache hider's GPSr has the same limitations yours does.

 

A 10-40 ft accuracy is okay...I feel really lucky if I can get less than 10 ft from the cache. After that, start looking for likely places to hide a cache. You'll develop that Geosense as you get more experience.

 

Also, since you have li'l fellas with you, they'll have more fun if you look for larger containers. They will like looking through the cache for trade items. It's also easier to find larger ones when you first get into caching.

 

Good luck!

[+schwachs]

That makes sense in regards to the accuracy... but will they bounce around so much? That was my concern w/ the iPhones gps and I can't imagine that one of the ones mentioned below is noticeably better... or am I just dreaming... cause it literally had us walking in circles...

 

-- Joshua

 

Joshua, no GPSr is going to be 100% accurate all the time. You have to take into account the satellites, clouds, trees, all those things.

 

In addition, you have to take into account that the cache hider's GPSr has the same limitations yours does.

 

A 10-40 ft accuracy is okay...I feel really lucky if I can get less than 10 ft from the cache. After that, start looking for likely places to hide a cache. You'll develop that Geosense as you get more experience.

 

Also, since you have li'l fellas with you, they'll have more fun if you look for larger containers. They will like looking through the cache for trade items. It's also easier to find larger ones when you first get into caching.

 

Good luck!

[+StarBrand]

The general accuracy of most handheld receivers is around 20 - 25 foot. Any readings inside of that will tend to be "bouncy" and a bit random looking at times.

 

Best bet is to put the GPS away and start looking around for likely hiding spots. Even when you can get a reading that is the "ground zero" of the coordinates you need to be prepared to search an area up to 60 feet away sometimes. You will often find the cache at less then 20 feet away but should be prepared for a wider area.

[+Zor]

Personally, I have found that the accuracy for geocaching on the iPhone to be pretty crappy. On most days, I get 9-15ft accuracy on my Garmin GPS.

 

As someone who only started caching last year, I can tell you that if you are frustrated by the accuracy issues of the iPhone, then getting a reak GPS receiver will vastly alleviate that frustration. Yes, depending on the cloud/tree cover and weather, accuracy will go up and down but real GPS receivers have a much better accuracy.

[+schwachs]

That makes sense... Again, I'm not expecting perfection but really just a decent range...

 

 

Personally, I have found that the accuracy for geocaching on the iPhone to be pretty crappy. On most days, I get 9-15ft accuracy on my Garmin GPS.

 

As someone who only started caching last year, I can tell you that if you are frustrated by the accuracy issues of the iPhone, then getting a reak GPS receiver will vastly alleviate that frustration. Yes, depending on the cloud/tree cover and weather, accuracy will go up and down but real GPS receivers have a much better accuracy.

[+Milbank]

cause it literally had us walking in circles

 

You get use to it, lol...

[NordicMan]

The GPS system in something like an iPhone was designed to get you within "sight" of your desired destination (gas station, ATM, restaurant, etc) For that task precice accuracy isn't important,, if it gets you within 50 feet of the restaurant you should be satisfied, correct?

 

Yep a dedicated outdoor/handheld GPSr is going to be more accurate, but still won't be perfect. Maybe within the next decade units will come out that you can watch the distance readout go 5 - 4 - 3 - 2 - 1 - 0, look down and THERE'S the cache!

[+ladyleo191]

Joshua, instead of walking in circles...try walking in a figure 8 pattern.

We call it the drunken bee dance (like honeybees dancing for the hive) and we all do it all the time.

[+schwachs]

It was a really big circle. :-)

 

cause it literally had us walking in circles

 

You get use to it, lol...

[+FrogAndPig]

Frog says:

 

This is a good question on one level. Although there are limitations to anybodys' GPS's accuracy based on foliage, clouds, rain, etc., different model's chipsets are more accurate than others in places like the woods and urban canyons. May as well seek out the most accurate GPS, yes?

 

For instance, I have a Garmin eTrex legend, which uses a different chipset than the garmin 60Csx. I have heard people say that the chipset on the 60Cxs is so good that you can get a position fix indoors. My eTrex does not. I would imagine that under a tree canopy, the 60Csx will outperform the Legend.

 

I may be wrong, but the Garmin 60Csx uses the SiRF Star III chipset, yes? The Legend has a previous generation chipset.

 

Supposedly the DeLorme chipset is better than the SiRF Star III, but I have nothing to verify this other than a post from DeLorme somewhere in this forum. Apparently, they're having issues with WAIS reception, which also affects accuracy.

 

When looking for a GPS for The Pig, I had been looking at the DeLorme PN-40 and the Garmin 60Csx, so I had essentially the same question.

 

Then again, I'm a noobie too, so take this with a grain of salt...

Edited December 15, 2008 by FrogAndPig

[+Prime Suspect]

Frog says:

 

This is a good question on one level. Although there are limitations to anybodys' GPS's accuracy based on foliage, clouds, rain, etc., different model's chipsets are more accurate than others in places like the woods and urban canyons. May as well seek out the most accurate GPS, yes?

Clouds and rain won't significantly affect GPS reception. If you allow water to collect on the antenna, however, that can make a difference. But in general, the GPS signal is weather proof.

[+FrogAndPig]

Frog says:

 

This is a good question on one level. Although there are limitations to anybodys' GPS's accuracy based on foliage, clouds, rain, etc., different model's chipsets are more accurate than others in places like the woods and urban canyons. May as well seek out the most accurate GPS, yes?

Clouds and rain won't significantly affect GPS reception. If you allow water to collect on the antenna, however, that can make a difference. But in general, the GPS signal is weather proof.

 

Like I said... grain of salt....

[+schwachs]

I picked up a the Garmin from Amazon... it's down to 261$ shipped. http://www.amazon.com/exec/obidos/ASIN/B000CSOXTO/02-4686-20 so I am hopefully it will be a significant upgrade...

[+FrogAndPig]

I picked up a the Garmin from Amazon... it's down to 261$ shipped. http://www.amazon.com/exec/obidos/ASIN/B000CSOXTO/02-4686-20 so I am hopefully it will be a significant upgrade...

 

Good for you. I'm leaning in that direction myself. I would consider the DeLorme, but its so new I would rather wait until several firmware updates come out before considering.

 

Sorry for the confusion about the rain affecting GPS signals. I looked into it further. I was basing my opinion on my experiences with my window-mounted GPS in my car during thunderstorms.... it wasn't the rain, but the wipers affecting the GPS signal.

[+Milbank]

I picked up a the Garmin from Amazon... it's down to 261$ shipped. http://www.amazon.com/exec/obidos/ASIN/B000CSOXTO/02-4686-20 so I am hopefully it will be a significant upgrade...

 

That is a great price. I see walmart had them for that price too online.

I think you had to pay shipping or ship it to a store for free.

 

Next time I'm in walmart I'm going to see if they have them in the store for that price too.

 

Please let us know what you think of the unit when you get it.

[NordicMan]

I don't think rain affects GPS performance significantly, but I do think I have noticed "wet leaves" can have a shielding effect to the signal if under heavy tree cover.

[+schwachs]

Will do! It arrives tomorrow! :-)

 

I picked up a the Garmin from Amazon... it's down to 261$ shipped. http://www.amazon.com/exec/obidos/ASIN/B000CSOXTO/02-4686-20 so I am hopefully it will be a significant upgrade...

 

That is a great price. I see walmart had them for that price too online.

I think you had to pay shipping or ship it to a store for free.

 

Next time I'm in walmart I'm going to see if they have them in the store for that price too.

 

Please let us know what you think of the unit when you get it.