GPS for "surveying"?

competentone

I'd appreciate any input you people could give me here.I don't have a GPS unit. I want to be getting one for a trip this Summer to Wisconsin. (Hopefully!)I specifically wanted to use the GPS unit to get a rough idea of the size and "shape" of some lake property (owned by the family for years) which hasn't had a recent survey.Anybody have any suggestions on a unit?And while I'm asking questions: Does anybody know a good surveyor in central/northern WI where I could get a proper survey incase we need it? (The property might be sold, or change hands in the family.)Thanks,Joe competentone@hotmail.com

He Dog

I don't have a GPS unit, but one of my hunting partners uses one. He loves tech gadgets, and has some program that allows him to down load the GPS data and overlay it on USGS topo maps. Seems like that might be useful for your survey project. If you are interested I will find out what he uses.

4wheeler

i do not own one but i talked to a surveyor and he said he did not use one because the accuracy is not good enough to survey with. he said that for $50,000 he could buy one that would work. a hand held unit will get you in the ballpark of where the lines are in my opinion. remember all the above statements are opinions only not from personal experience.

Nate

The GPS units that are used for surveying are very expensive. They take the readings from the 24 orbiting satellites (21 active and 3 spares) that were put into space by the U.S. Department of Defense in the early 1990's.These units are large and have to be left in place for an hour to get a reading that is accurate to about 1/100,000 of an inch, when left there for 3 hours you get an accuracy of 1/250,00 of an inch. Once a point is found it is used as a base point for survaying by a more conventional mannor. Using a total station, etc...

hunter280man

I have and love the Garmin in almost any model. They pickup and work in heavy timber, plus they are user friendly. Even I can find my way around a mountain with or without a map. When out in colorado last we had 4 or 5 different models and only one other worked on our mountain. It was a eagle at twice the cost. I had a 12 and my father had the 12XL They out-performed the others we had by a long shot! Now as for surveying? I only think you can get up to 30 to 40 feet of accuracy. Possibly a little less I'm not sure. I have a surveyor friend that uses the back pack style with the stick wand to touch things and log them in his mobile back pack to make maps later. He says the garmin is the best he has seen in the hand helds, I read the GPS and he reads or put the numbers on the topo while on a 2 day stalk hunt. We hit every waypoint within 20ft+or-.

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Though I was born to royalty, I was snatched at birth, so treat me as the noble I am!!![This message has been edited by hunter280man (edited 03-22-2002).]

cowdoc

i have a garmin gps 12 hand held i use it to mark canada thistle patches to spray (also big solid rocks that i need to dig out) i carry it in the pickup tractor or combine when i decide to go spray them i can go right to where they are and get them. also works nice to build a straight fence on my place where there are hills and cant see the other end to line it up.when i mark a way point i can go back to it with in a few feet aprox 3-5ft i want to get a guidance system to put on my sprayer soon which is accurate to within about a foot. doc

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I dont give my guns without somebody getting hurt!i usually get 10 to 11 satellites on any given day which i would imagine helps accuracy.[This message has been edited by cowdoc (edited 03-22-2002).]

Richie Rich

I have a garmin plus II and my father-in-law did too (GOD REST HIS SOUL) before he past on, my hunting buddy does not all the extras so he went with the garmin etrax( he had an old 12 but was old and needed upgraded. Cabelas has alot of models and is a good place to start pricing. One thing for sure keep extra batteries and it will get you back to the truck.

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Remember,"your woman may not find you handsome, But atleast she'll find ya handy". I love that show..............

Boomerang

The GPS units that one gets for hunting or navigating on water is not as accurate as the GPS units used for surveying purposes. It should be noted that these cheap/simple units that cost $150 could be very accurate, but the military sends out error signals called "dithers" that prevent/impedes potential use by foreign governments with hostile intent to the US. Of note, the "dithers" were disable during Desert Storm for use against the Iraqs when we were targeting bombs and navigating the desert. FYI, the GPS units used for surveying can be rented. Don't know how much though.

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Protect our Constitutional Rights.

Mr. Lobo

Hi, competentone,I am the manager of a surveying and mapping company in California we use both types of GPS equipment listed above. The hand held is single frequency and its accuracy is +/- 10 meters. The next level up is also single frequency but it used radio corrections from a third party and had a sub meter accuracy, this system is used for GIS and Environmental surveys. The ultimate is the Dual Frequency receiver, which will achieve sub centimeter accuracy. The costs are about $200, $15,000 and $45,000. We use the hand held to get close to the areas of search for NGS monumentation or to navigate through city streets. The other unit that we have is a sub centimeter receiver, which we use to perform topographic, boundary, and construction surveys. There is no way to achieve any better precision from these units but the best way to achieve the highest accuracy is to take readings during the morning and the afternoon this will give you information from two different satellite constellations. You will then mean that data and this will be of the highest accuracy that you will be able to achieve. You might be able to get a map of your lakes if you do some research at your county map records department. They may have a topographic map of your property already done. Usually these maps are used for flood control studies. Hope this helps.Jim

Mr. Lobo

The military turned off their scrambling a couple of years ago because the president decided that commercial aircraft and others needed the higher accuracy to help them navigate. Prior to that the handheld receiver accuracy was about 30 meters.Jim[This message has been edited by Mr. Lobo (edited 03-23-2002).]

Alpine

I have 3 GPS handhelds. An older Magellan, and two of the newer cheaper (I paid $900 for the older Magellan) Magellan and Garmin).The newer handhelds can be found for about $100 and they are good to about 30 feet. This is dependant on the satillite positions. If you live in an area that has differantial beacons you can get an additional feature on some models to get to the three meter accuracy. Although most of the beacons I'm aware of are on the coast.

competentone

Thanks for all the replies!The input you've all given is EXACTLY what I'm looking for.Thank-you.Joe

gunnut505

Like the L.S. from California said, your handheld will only get you close- the units used by my organization are Trimble 5700's with internal modems for RTK, or Real Time Kinematic Surveying where you utilize a known point for the base, and the "rover" receives corrections every 1/2 second. when we use 2 bases; we are able to receive positional corrections from 2 known positions, and therefore are able to resolve positional tolerances to around one part in 5,000,000. But that's after calibrating our Datums and Projections with several nearby known points.Garmin is good, Motorola is ok, trimble's is the best.