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Military GPSr's


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I know the military has more accuracy then civilian GPS. How accurate does a military GPSr get?

What kind of unit do ground troops use? Say like a special forces unit. Do they have a sooped up Etrex or what?

 

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Not sure exactly what they get, but I saw a photo of a military vehicle (in Iraq) in the NY Times a few weeks ago and there was an eTrex Vista sitting on the dashboard.

 

"It has been my experience that folks who have no vices have very few virtues" -Abraham Lincoln

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Red Team,Blue Team....Good Guys, Bad Guys...I think thats how it works.The Units they use are specially built to withstand Combat Conditions.GPS is GPS the math is all the same it who has the Technology and patience can get the same results.I could go into more detail on how the good guys can lead the bad guys right into a trap (S.A.)And GPSR detector ,detectors and and and and .....

 

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This has been discussed before, but I don't want to Markwell you. The satellites send two signals--the signal you can pick up with a civilian GPS unit, and a second signal that is used to correct for ionospheric intereference, and only military GPSs (known as PLGRs, for Portable (?) Light (?) GPS Receivers) can receive the second signal. I don't know how accurate the current generation of PLGR is compared to a civilian GPS-R--I've used three different systems that have a PLGR with them, but the PLGR is used just for the time hack.

 

"People think it must be fun to be a super genius, but they don't realize how hard it is to put up with all the idiots in the world."--Calvin

 

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When the most recent war started, I saw a TV show talking about the "tools" of the modern military. One of the items they showed was an off-the-shelf Garmin Rino120. They like the peer-to-peer positioning capability so they know exactly where each other is.

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The main difference between one system and another is what is done with the received signals. In other words, the depth that is gone to, to check quality of the result between one fix and the next, how many fix cycles are considered in the 'weighting' that is applied to a particular fix, the 'health' of each satelite and a whole host of other things. Then there is 'differential corrections' - all adds up to more computing power being required to achieve the result. If one wants the best accuracy then one pays more for the unit and it's likely going to be bigger than a hand held.

In this way, probably, some units in use by the millitary will be better than we use in our application. I mean, who has the bigger budget and the Hummers to drag the kit around in?

Wish I did!

 

Only nuts eat squirrels,

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I've heard/read that it also has to do with the grade of materials used in manufacturing, most important, the time-keeping aspects of the devices.

 

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First of all,,, as far as I knew, the military GPS accuracy is the same as civilian, as far as the handheld units. Im sure they have a couple GPSr that are better, especially the ones built into the vehicals. When WAAS came out, they were going to make it strictly for military use. But they figured that if they let civilian companies use it, that they could help improve it. That way everyone wins. The government reseives the EXACT same signals from the EXACT some satillites.

When Operation Iraqi Freedom was on the news,,, guess what the #1 GPSr I saw over and over? Yep, my trusty Garmin etrex Vista. I saw at least 3 troops with in clipped to the front of their vest, and one news and jornalist crew with it on the dash of their truck.

Im sure they probably have a few units that can take alittle more punishment physically,,, but Im pretty sure that as far as accuracy goes,,, their handhelds are no better than the best civilian ones.

 

[This message was edited by jtice on May 08, 2003 at 10:49 AM.]

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15Tango........

 

We seem to have different information on the signals I see. Id like to see some information on your view of it. (not saying your wrong, just want to know). When I first got my Vista, I read information on Garmins site, and then a few others I found on Googgle. They all said the sats send out the same signal to everyone. It was my understanding that only the GPSr could make the difference by recieving the signal better, and keeping better time.

The main thing that told me that the military and civilian signal is the same,,, is when they desided to let civilians use WAAS also. That way everyone was on a level playing field, and all the civilian companies could pore thier money into developing better products as well. That way, the civilans would actually be helping out the military. And visa versa,,, but they are more interested in us helping them. icon_wink.gif

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I've used the military pluggers quite a bit. They're much more accurate than civilian GPS when it's been unlocked. In the plain Jane setting it's about the same as civilian GPS. But when the coding is unlocked it's very accurate; however, it then becomes a classified piece of equipment. How accurate? We use to play a game (pre-Geocaching days) where we'd hide ammo cans in the desert, then go tactical at night (absolutely no lights) and go looking for the cans. With the unlocked plugger it would take you where you'd step on the can. It isn't like the civilian GPS where you'd be within 15, 20, 30, whatever feet. It would take you exactly to the location. They were that accurate.

The pluggers also had attachments which made them very very kewl toys.

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quote:
Originally posted by oregonature:

I know the military has more accuracy then civilian GPS. How accurate does a military GPSr get?

What kind of unit do ground troops use? Say like a special forces unit. Do they have a sooped up Etrex or what?


 

In my limited exposure military IT and Communications system I can tell you this with some certainty: You will only know the accurate answer to your question if you get a top secret clearance and a need to know, or you wait a few years for the current crop to be declassified and released to the public.

 

I actually interviewed for transfer to another Navy unit recently, and the interview went something like this:

 

Me: So, what projects will I be working on?

Them: I can't tell you.

Me: What type of equipment will we be working with?

Them: I can't tell you.

Me: Can you give me an idea of what the job will involve?

Them: No. Interested?

Me. Hell yes.

 

ApK

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Some of this PLGR accuracy stuff really needs to be put into context as PPS receivers have other capabilities to improve accuracy apart from C/A, P and encrypted P(Y) codes.

 

Any receiever (each and every individual one) with a PPS module (in use or not) is classified and must have written approval from JPO, USAF.

 

Prior to SDGPS PLGR's used Wide Area GPS Enhancement (WAGE), which is spec'd at <4mCEP as the first PLGR's couldn't use differential because PPS is not based on pseudo-ranges, so SDGPS wasn't an option. The newer PLGR's with SDGPS capability, the accuracy is less than 1m but none of this type of accuracy is possible without augmentation of some sort.

 

If PLGR's were as accurate as some claim then there'd be no reason in spending the $$'s developing some of the other military real-time systems, which are accuracy critical.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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First experience with military gps was called a slugger. It was large, heavy and i hardly ever used it. I have used the PLugger and it works outstanding. We used it for coordinates marking danger areas, they were dead on. But they were still large and heavy and chewed up the special lithium batteries. Currently you will see allot of soldiers who opted to buy there own. Most widely owned are Garmin Etrex and some emaps. That is my expereince anyway. i am sure others have seen different

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quote:
Originally posted by oregonature:

I know the military has more accuracy then civilian GPS. How accurate does a military GPSr get?

What kind of unit do ground troops use? Say like a special forces unit. Do they have a sooped up Etrex or what?

 

Did you know that the base of my wine glass fits perfectly into a family size tomato soup can?


 

The one I used was a Canadian Military one that when you didn't have the crypto (secret stuff) in it, It was well useless. It took a 2 to 3 day course to use it and it was the size two bricks side by side and about the same weigh icon_biggrin.gif. What I found funny was that we have this new high tech stuff (GPS and raidos) but I saw the 1st and 3rd Battalion Royal Canadian Regiment (Infantry) useing etrex's and FRS radios in the field all the time icon_smile.gif

 

Work Smarter, Not Harder!

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My former unit flew F-16s. We issued our pilots Garmin 12. Our sister unit issued their pilots Garmin III+. Not sure why they went to the extra expense of the III+. Joke was in case they had to punch out, with the roadmaps in the III+, they could more easily find their way to the nearest bar.

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I trusted my life to a Garmin Etrex Vista during Iraqi Freedom. The only time the PLGR came out was when we were...... never mind. The PLGR was the heat when it came out but just like all military equipment the procurement cycle makes it obsolete a year or two after it hits the team. S/A not withstanding, the Vista, or any other modern GPSR blows the doors off of the PLGR for ease of use, functionality, and size. Hell the Vista does MFF calc now.

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I forget what the GPS unit was named, but during the first Gulf War my SFC was showing around a GPS. It looked pretty interesting but he wouldn't let anyone touch it. I thought it was pretty cool. We couldn't put some to good use out there. It's too easy to get lost out in the desert.

 

[This message was edited by Shychief on May 14, 2003 at 08:40 AM.]

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In a nutshell -- the more accurate the internal clock the more accurate the unit. Off-the-shelf survey grade civilian units are now sub-millimeter accuracy, but you pay for that accuracy.

 

I read an article some time ago about the newest survival radios for pilots. Combined radio and GPS with a twist. Just a push of a button transmitted the coordinates in an encrypted burst so the bad guys could not intercept the signal and get to you first. Pushing another set of buttons 'fried' the internal electronics (in case of imminent capture).

 

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quote:
Originally posted by Dave54:

.... the more accurate the internal clock the more accurate the unit.


 

What? the internal clock in the GPS receiver (I assume that's what you mean). Apart from basically telling the time it doesn't do anything for accuracy.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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I have used the Plugger some with the USDA. Agency bought them and had access to the codes. I had my own Magellan 4000 at the time. The accuracy of the plugger was better when SA was active. I still used the 4000 most of the time unless I needed the accuracy, since it is smaller and more user-friendly. After the SA was turned off I could not tell the difference. Since then we have gotten rid of the pluggers and have Garmin gpsmap 76. I like them so well I bought one for myself.

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quote:
Originally posted by Kerry:

quote:
Originally posted by Dave54:

.... the more accurate the internal clock the more accurate the unit.


 

What? the internal clock in the GPS receiver (I assume that's what you mean). Apart from basically telling the time it doesn't do anything for accuracy.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif


 

Wasn't there a SciAm article recently that explained how a super-accurate clock in a GPSr would allow for more accuracy...something to do with being able to detect time errors better?

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One more link...

http://www.zyfer.com/research/whitepapers/pdf/SAASM_White_Paper_April_2002.PDF

 

Excellent white paper from a military developer of PPS systems...illustrates the differences between military/civilian GPS/PPS...there IS a unique military signal. Most of the sophisticated military uses are for weapon systems/aviation nav systems...reading the latest on Differential GPS...nextgen...the target is for 20 CM accuracy...Wayne

 

Never say Never...Never say Always!

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PLGR stands for Precision Lightweight GPS Receiver. It was the standard GPS device for the Army and Marines in 1999-2000, but it may

now be updated for AD component soldiers.

 

It is true when SA was lifted, off the shelf

GPS devices could be as accurate a PLGR. There

was no scrambled signal that you needed a secure variable to descamble, as with a PLGR.

 

But PlGR's as noted, also served as a very accurate clock for other military devices

such as the SINCGARS radio and ANCD's. That time, as common knowledge is available on it, keeps

the radio net in sync. PlGR's also did other

useful things, but as direction finders, they

are not that special now.

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I work part time at a Gander Mountain store here in this area....a few months ago I had a fella from England visit the store...he was visiting relatives. He was with the "Territorials" (like our National Guard). He (like many of our troops) wanted a GPS....and ended up with a Garmin Legend. Many of our troops don't have access to the military units......and are carrying their own...

 

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The Plugger (PLGR) was only a single frequency unit and if one looks back at the spec in 1998 the horizontal accuracy @95% was 22m, vertical 27.7m and time 100 nanoseconds. Back then similar SPS accuracy (with SA) was horizontal 100m, vertical 156m and time 340 nanoseconds.

 

The current 95% SPS SIS spec of horizontal 13m, vertical 22m and time 40 nanoseconds, however these are Signal-In-Space parameters but still very competitive.

 

The replacement for the PLGR is the DAGR, which is a dual freq receiver and handles real-time systems as well, which the PLGR simply couldn't.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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