From: Glen Closson (glen_closson@earthlink.net)
Date: Wed Dec 21 2005 - 15:09:58 PST
Peoples,
Please take a look at http://www.trimble.com/gps/
for a great, easy to understand discussion about GPS, differential GPS and more.
It should answer many of our questions.
Glen
-----Original Message-----
>From: Bill Kealey <cwkealey@atlanticbb.net>
>Sent: Dec 21, 2005 4:42 PM
>To: Military Vehicles Mailing List <mil-veh@mil-veh.org>
>Subject: Re: [MV] speaking of GPS.....
>
>
>
>>I sure would like to know where you all are getting the high speed stuff to
>>give such good coordinates........in the military (as I am and have been
>>for 18 years) we can only get as close as 10 feet. If you all can send the
>>updated codes I would gladly use them ........then again I am a Marine and
>>should probably check with the AF or the Navy to get the good
>>stuff......ours will probably come to age when you all get the "new" stuff.
>>
>> ......but still wondering how you all get to 1 foot?????
>>
>>
>>
>> SSGT SMITH CN
>> USMC MITT, 1ST BN, 3RD BDE, 7TH DIV
>> NUMANIYAH
>> APO AE 09331
>>
>> M880, M274A5, 6K GenSet
>
>
>
>Cliff,
>
>I was always told that the best my unit could expect to do on a good day was
>about 3' or 1 meter. Playing around in the police boats and pilings that
>are usually considered "fixed objects" I found that the accuracy was, as you
>said more like 10' to 12' or approximately 3 meters.
>
>My GPS altitude readings are so far off that I have never found them to be
>useful to me. When I lived near and worked on Chesapeake Bay, altitude was
>never an issue. We didn't get any tsunamis that I recall so basically the
>tidal difference was all I had to adjust for and did not need GPS for that.
>
>I am now with the local fire department in the mountains and the altitude
>readings could be very helpful with Search and Rescue here with the use of
>topo maps. Again, the unit that I use shows it is rarely more accurate
>then within +/- 185 feet or so. I am situated in a valley between two small
>mountains with a third splitting them about a half mile or so from my home.
>
>I know that our engineering division used to have to hook up two antennas to
>the GPS and separate the antennas about 4 or 5 feet to get accuracy good
>enough to be useful in court and it did work. They were using the same
>Garmin 45 at that time that I use now. Again, that was at least 10 years
>ago so I know that the technology has improved quite a bit.
>
>I certainly would not want to use my GPS unit to do an accurate survey of my
>property line (or say, a mine field) but would have no problem using it as a
>reference tool.
>
>And, to put the accuracy in a different perspective, how much compensation
>does one allow for the width of a pencil point when locating your position
>on a map/chart? This can certainly open another can of worms as pencil
>points vary quite a bit depending on many factors such as, the sharpener
>used, how long between sharpenings you have been using it, diameter of lead
>used if a mechanical pencil and other things. We also have to compensate
>for the proportional size of the map/chart being used.
>
>So, IMHO, unless the GPS units are that much more accurate than what I have
>been using all these years I personally doubt that the units are normally as
>accurate as advertised. However, anything is possible.
>
>
>Have a great day.
>
>Bill K.
>
>
>
>
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