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Gps Equipment Questions


whits_end

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I'm very, very new at this. But I loved the idea of it so much that I ran out and bought a GPS unit without really knowing what I was looking for. We've used is a few times and feel it's a bit awkward to use. So my question is this, "Is it normal that a GPS unit must be moving forward before it gives you accurate information?" :)

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Where you are is accurate. I'm thinking you're talking about which direction you are moving or oriented is being inaccurate.

 

Most GPS units use where they are and where they've been to know which direction that are moving. Most don't know which direction they are oriented.

 

So, to answer your query, yes it's normal.

 

CR

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If you have a gps that has an electronic compass it should give accurate info while you are standing still, depends on which unit you bought. There are typically two different types of compasses the one that works while standing still requires calibration before use.

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I'm very, very new at this. But I loved the idea of it so much that I ran out and bought a GPS unit without really knowing what I was looking for. We've used is a few times and feel it's a bit awkward to use. So my question is this, "Is it normal that a GPS unit must be moving forward before it gives you accurate information?"

No, and Yes.

 

Your current position (latitude and longitude) can best be determined while you're standing still. That goes for the distance to your target, as well, since that's calculated from your coordinates, and that of your target.

 

However, unless you have a GPS with an electronic compass (and I'm pretty sure you don't), it can ONLY determine your orientation by deduction, and that can only be done while you are moving in a straight line. Basically, it takes your position from a few seconds ago, and your current position, and assumes that you're walking in a straight line with the GPS pointed in front of you. From those assumptions, it can determine the orientation of the GPS, and from that, it can display the direction arrow in the proper position.

 

3608_2800.gif

"Don't mess with a geocacher. We know all the best places to hide a body."

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Nearly all the info on the GPSr is accurate at all times (or at least as accurate as these things are:D). I also assume you mean the compass screen, and yes, you must be moving for it to know your direction. Once you stop, if you turn around, the unit has no idea that you turned, only your position/direction relative to where you came from.

 

BTW, the Magellans have a nice feature called "north finder", which shows a sun and moon icon on the compass screen. Lining that icon up with the position of the sun/moon results in the compass screen also being oriented correctly while standing still. Even my original GPS, the basic Magellan 315 had it. It's a very handy feature that can be used day or night, as long as you can see where the sun or moon is, and I'm surprised Garmin hasn't added it to their units.

 

Only the more expensive units actually have a "magnetic" compass built into them. Personally, I don't think the extra $100-150 for that feature is worth it; I can buy a nice handheld compass for much less; but to others it's worth the extra money.

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Also know that while standing still the gps will "jump around" a bit. You will be able to watch your Lat and Lon move up and down a little as time goes by.

What's fun to see is placing your unit on a picnic table somewhere making a waypoint. Do a GOTO to that waypoint and watch the pointer move around--all the while, you haven't moved the unit.

 

It's easy to visualize the point move around your realworld position. It's like you're anchored on the bottom of an electronic ocean while the waypoint is a bouy that is floating around your position.

 

This is really pretty close to the case as the atmosphere is pushing and tugging the signal the unit is receiving.

 

CR

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:) If you truly are "new" to the sport, I believe someone should tell you that many questions about a GPSr are best answered "yes" and "no". That's because the performance of one make/model will differ, at least to some degree, from another make and model. You can do a search on the web to find the manufacturer of your GPSr and, in many instances, download an instruction manual that should answer most of your questions. IMO, you are mislead when others provide you with specific answers to general questions without knowing more about what you're using.

The site offers a forum to address specific questions about GPS units:

 

GPS Units and Software

Any and all discussions about GPS units. Here you can talk GPS, GPS Units, and those miraculous satellites that give our game life.

Forum Led by: Hemlock

 

that may better serve your need for answering questions about issues that are not clearly explained (and there's probably going to be a bunch of 'em) in your GPSr manual.

Edited by gallahad
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Your position can also change as the number of satellites with a good lock changes. IE: 8 satellites will position you better than just 4, and even when standding still, the satellites play hide and seek with ya a lot. As time goes on, ya get used to this with experience.

 

Hang in there, it gets easier ! practice some in an open filed first. set an object, waypoint it, walk away, and "find" it only by co-ords. Do it from numerous approaches. Take note of the variations that occur. Is the variation following a pattern ? Like a car, you learn the nuances of YOUR particular unit. For instance, mine seems to be off on the east-west coords.

 

Once you've become familiar in the open, try it under tree cover; same drill of "hiding" and "finding"

 

Even all this familiarizing, you still will have to just beat the bushes sometimes. the signal difference between your gps and the hiders, as well as reception are factors in accuracy of co-ords.

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I believe that some of the accuracy has to do with the "random" info thrown out by the satellites so we cannot get such a close "lock" on a location. With security being elevated with our war in Iraq -- this has become standard practice (at least for now).

 

Someone please correct me if I am wrong, but I read that this was a case.

 

It is kinda annoying that you have to move sometimes several feet in order for your position or distance to destination change. It'd be nice if it picked up movement of inches and adjusted your position -- this is not a case!

 

In my limited experience, I have found that when you get down to the last bit of your cache hunt, you have to beat the bushes -- not rely on the technology.

 

Bozz

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It is kinda annoying that you have to move sometimes several feet in order for your position or distance to destination change. It'd be nice if it picked up movement of inches and adjusted your position -- this is not a case!

The numbers that a consumer GPS puts out (3 digits after the decimal point of minutes) can only resolve to about 5 to 6 feet or so.

 

Or, to put it another way, 0.001 minutes of a degree is about 5.8 feet or so. The exact measurement depends on where you are.

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It is kinda annoying that you have to move sometimes several feet in order for your position or distance to destination change.  It'd be nice if it picked up movement of inches and adjusted your position -- this is not a case!

The numbers that a consumer GPS puts out (3 digits after the decimal point of minutes) can only resolve to about 5 to 6 feet or so.

 

Or, to put it another way, 0.001 minutes of a degree is about 5.8 feet or so. The exact measurement depends on where you are.

5.8 feet I believe refers to the latitude difference which stays the same. However, .001 degrees varies on the longitude. The distance gets smaller as you move from the equator to the poles as these lines converge.

 

Of course I've never been to the North or South Pole so I'm only assuming someone else has proven that! :D

 

alan

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