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Newbie has questions - help!!!


artysta

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Hi! I am new to this whole thing and I want to buy my own GPS to go Geocaching. My problem is this...my friend said that if you get a "cheap" GPS that you can't get an accurate enough reading when you get close to your cache and stop moving. Does anyone have any suggestions on which GPS model is at least "good enough"? Any suggestions you have would be great! Thank you!

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I think that the street price for a Garmin eTrex is < $100. It is certainly accurate enough for caching. Your friend might be referring to an old averaging problem in the Magellan GPS 315 [now discontinued [i think), but can be found for a good price). Most users do not find the averaging issue that big a problem, and I believe it has been greatly reduced in a firmware update.

 

Your friend might have been talking about GPS receivers giving poor bearing indications when you are moving slowly, near a cache site. This is because most GPSr's don't 'know' true heading (which way you are facing). They infer heading by position changes over time. That is, they assume you are walking in a straight line, and facing exactly the direction you are heading.

 

This is often not true at slow speed or stopped, or on rough terrain (like on a trail, looking around for a cache). Some GPSr's do have a built in electronic compass, which elliminates this problem, but you can solve the problem with a $15-$20 compass as well (which is also a handy thing to have when you hike outdoors).

 

You can tell your friend that my young daughters have found over 30 caches now using just a Silva Ranger compass, a USGS topo map, and an aerial photo from http://www.lostoutdoors.com icon_smile.gif Just about any currently manufactured GPSr would easier...

 

Good Luck!

-jjf

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I think that the street price for a Garmin eTrex is < $100. It is certainly accurate enough for caching. Your friend might be referring to an old averaging problem in the Magellan GPS 315 [now discontinued [i think), but can be found for a good price). Most users do not find the averaging issue that big a problem, and I believe it has been greatly reduced in a firmware update.

 

Your friend might have been talking about GPS receivers giving poor bearing indications when you are moving slowly, near a cache site. This is because most GPSr's don't 'know' true heading (which way you are facing). They infer heading by position changes over time. That is, they assume you are walking in a straight line, and facing exactly the direction you are heading.

 

This is often not true at slow speed or stopped, or on rough terrain (like on a trail, looking around for a cache). Some GPSr's do have a built in electronic compass, which elliminates this problem, but you can solve the problem with a $15-$20 compass as well (which is also a handy thing to have when you hike outdoors).

 

You can tell your friend that my young daughters have found over 30 caches now using just a Silva Ranger compass, a USGS topo map, and an aerial photo from http://www.lostoutdoors.com icon_smile.gif Just about any currently manufactured GPSr would easier...

 

Good Luck!

-jjf

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quote:
Originally posted by jfitzpat:

Your friend might be referring to an old averaging problem in the Magellan GPS 315 (now discontinued (I think), but can be found for a good price). Most users do not find the averaging issue that big a problem, and I believe it has been greatly reduced in a firmware update.


 

I'm curious about the averaging problem you mentioned. This past Saturday, we had our first MIGO picnic, and played a game with our GPSr's to get a taste of the differences in accuracy. The "master" coordinates were obtained with a 315, set on autoaverage for 20 minutes. A couple of hours later, when we did the actual "Pin the Coordinates" contest, all the readings...including the original 'master' unit...were about 35-40' to the west of the original location. (I'll have to e-mail the owner, and see if he's gotten the firmware update you mentioned.)

 

-------

"I may be slow, but at least I'm sweet!" 196939_800.jpg

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quote:
Originally posted by Zuckerruebensirup:

 

I'm curious about the averaging problem you mentioned. This past Saturday, we had our first MIGO picnic, and played a game with our GPSr's to get a taste of the differences in accuracy. The "master" coordinates were obtained with a 315, set on autoaverage for 20 minutes. A couple of hours later, when we did the actual "Pin the Coordinates" contest, all the readings...including the original 'master' unit...were about 35-40' to the west of the original location. (I'll have to e-mail the owner, and see if he's gotten the firmware update you mentioned.)


 

Well, a 30' shift might not be averaging, it could just be the geometry of the available sats changing over time.

 

There are actually several existing threads on the GPS315/GPS320 averaging and workarounds, those would probably explain better than I could (I've seen GPS315 users wave the unit around their heads, but I wasn't sure if the act actually effects averaging, or just gives them something to do while they wait for the averaging to catch up... icon_wink.gif)

 

I will say that averaging does not demonstratably improve accuracy, not that SA is off. So, I personally, would not go out of my way to buy a receiver that offers it.

 

-jjf

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quote:
Originally posted by Zuckerruebensirup:

 

I'm curious about the averaging problem you mentioned. This past Saturday, we had our first MIGO picnic, and played a game with our GPSr's to get a taste of the differences in accuracy. The "master" coordinates were obtained with a 315, set on autoaverage for 20 minutes. A couple of hours later, when we did the actual "Pin the Coordinates" contest, all the readings...including the original 'master' unit...were about 35-40' to the west of the original location. (I'll have to e-mail the owner, and see if he's gotten the firmware update you mentioned.)


 

Well, a 30' shift might not be averaging, it could just be the geometry of the available sats changing over time.

 

There are actually several existing threads on the GPS315/GPS320 averaging and workarounds, those would probably explain better than I could (I've seen GPS315 users wave the unit around their heads, but I wasn't sure if the act actually effects averaging, or just gives them something to do while they wait for the averaging to catch up... icon_wink.gif)

 

I will say that averaging does not demonstratably improve accuracy, not that SA is off. So, I personally, would not go out of my way to buy a receiver that offers it.

 

-jjf

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Problem with 315 / 320 auto averaging used to be that if you started to move very slowly, the unit would assume that you are stopped and started to average the position even that in fact you were moving. If you were moving VERY slowly, you could’ve moved by 10 or 20 meters before the unit figured out that the actual position has changed and it would re-adjust and start auto averaging again. No problem at normal walking speeds, but a drag if you want to take few steps and look around and few steps and…

One way to make the unit to snap out from autoaveraging and recalculate curent position it was to… wave it.

Anyway; this is history. Current firmware update does away with that problem. If you have a 315 or 320, download the firmware update from the support section of www.magellangps.com

 

Andrew Kalinowski

 

www.GPSNuts.com Recreational GPS and mapping (hobby)

www.CanadianMaps.ca Raster topo (and some other) maps

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I've used an etrex yellow in the woods and it kept losing the signal. I have a Mag 315 and it does a lot better in the trees because it uses the quadrifilar antenna instead of the patch antenna.

 

The averaging thing was a little annoying when I was running version 2.03, but now that I have version 3.15 loaded it works great.

 

The 315 is still for sale and I think it is more than adequate for a starter GPS. If you buy one, make sure that it has version 3.15 installed as it doesn't come with a computer cable

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curious as to the response time of various units. we bought our "new" garmin 45xl at a garage sale for $10, got to love them garage sales, we don't know nothing about this game other than we are having a ball and plan on cvontinuing with it. our problem, although minor, is the response time of our 45xl, i don't expect any miracles but it seems to take us some time to get close to ground zero, is there something we need to be doing, would a newer unit do us any better? we like the external antenna option. thanks, bob, rjr13

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quote:
Originally posted by artysta:

Hi! I am new to this whole thing and I want to buy my own GPS to go Geocaching. My problem is this...my friend said that if you get a "cheap" GPS that you can't get an accurate enough reading when you get close to your cache and stop moving. Does anyone have any suggestions on which GPS model is at least "good enough"? Any suggestions you have would be great! Thank you!


 

As long as you get a modern unit (and not something discontinued years ago), it will work. Some units (eTrex) have worse reception under tree cover. If you do not get a unit with a compass built in, then get a $10.00 compass from your local sporting goods store. When you are not moving, you cannot depend on the "arrow" on a GPS. Instead, take the bearing and use a regular compass.

 

For a beginner, the Magellan 315 (with the new firmware!) or an eTrex would be a good introduction to GPS and Geocaching.

 

Then, after you figure out what you like and don't like, you can sell your old unit on eBay for around 80% of the purchase price, and buy yourself something nicer with mapping.

 

Have fun, and don't forget that there is more than one web site devoted to this sport!

 

-----

Any similarity between my opinions and reality is entirely coincidental.

--Harrkev

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