GPS - Trust / Don't Trust

[SeanNewman]

Bullet Magnet,

The old me would have gone on a rant about a military GPS being different than a store-bought Garmin, and any error in the grids being because the user entered the wrong system like MGRS, etc (similar to a compass being "right" but the user having the wrong magnetic declaration set), but I am actually curious about your answer.

So before I discount it, can you please tell me what you meant by spoofing my PLGR/DAGR? 

 

[George Wallace]

They key pont is that people are the point of failiure in navigation. It is people who do not carry sufficient batteries for the task. It is people who do not update stored digital maps. it is people that cant read what a GPS is telling them and it is people who cant be bothered to learn how to use them properly.

Automobile GPS.......well they are a beast on their own but even then, updating your maps goes a long way.

I think I alluded to this a little earlier:

Then again, there are those who would be lost no matter what they had as a navigation aid.  ;D

And as far as the land/air GPS argument goes, i have been in both environment using GPS so i am not entirely clueless.

Great.  Has anyone questioned that?  I feel comfortable doing Recce or Tanks.  Most have a problem with one or the other.  So what?  So you feel comfortable doing both.  As we know some don't/can't; and some can't do either. 

Yes.  Ultimately it is the person who will be at fault.  Then again there are extenuating circumstances, such as the many editions of CFB Gagetown maps where MCE placed a road on the map that was at the top of Headline Hill south at an intersection above Bell Bridge.  I think it is only recently that that curved tank track off the Lawfield into WTP has been placed at the correct grid.  The old maps had it going through where an old house used to be at Bell Bridge/Ford.  Oh well.

 

[SeanNewman]

As long as the sh!tters at the Nerepis Biv are still at grid 123456 I know my map/compass/GPS are zeroized.

 

[George Wallace]

As long as the sh!tters at the Nerepis Biv are still at grid 123456 I know my map/compass/GPS are zeroized.

Once upon a time there used to be a house at that location.  I used to use that grid when teaching map using at the School.  Can't use that anymore, as when they did the rejigging of Grid Lines in the mid '90s, when they started correcting old surveys with GPS and Satellite imagery Grids have moved a one or two hundred meters.  The house is probably a ruin today anyway; and hopefully the basement plowed in.

 

[Jarnhamar]

Edit: question answered in PM thanks

 

[aesop081]

I use the GPS in my iPhone regularly to measure my runs and walks. i drove the routes to compare and the GPS is bang on.

 

[George Wallace]

Your GPS is more accurate if you "move".  If you have some sort of software ( I use GPS Photolink) and download your Track onto your computer or input into Google Earth, or if you have the patience to sit in one place for a while (a long while) you will see that a stationary GPS will bounce your position around up to 50, and occassionally 100 m.  (Civi GPS)  Once you move, you will see that your location more closely resembles you position on the ground.    I have not experimented with PLGR, so I will not make the same comments on it.

I have had some problems with my personal GPS due to loss of satellites, or low battery power.  Other problems occured due to being stationary for too long and under too much overhead cover (again loss of satellites). 


Love my GPS for marking distance, time and average speed, etc. of ruck marches. 

 

[SeanNewman]

...The house is probably a ruin today anyway; and hopefully the basement plowed in.

Any remnants of any houses that existed in the 50s have now been essentially destroyed.  At first they were not and they were just left abandoned, but of course over time the troops would end up going in them when on Exs and all it takes is some garbage like a used IMP being left in there and it was mice and insect central, so they were all destroyed.  There may be the odd rubble left but nothing resembling a house.

 

[George Wallace]

I remember whole villages out there into the mid '70s.  However, troops on Winter Exercises/Trg often took shelter in them, and quite often burnt them to the ground with fires (cooking or for warmth) or through the use of munitions in assaults.  Later, the unfilled basements offered many a Tanker a bad day when they suddenly found themselves in one.

 

[HItorMiss]

It's hard to get into on an open forum....

However What I can say is there is technology out there that will grad your GPS signal and from there people behind computers can subtly or not so subtly change all your grids.

For instance my GPS should read 18T UR 3456 0987..... My GPS is grab by the techno geeks so My GPS now reads 18T UR 3462 0976.... and from there everything is slowly and subtly changed to move me where they want me.... It doesn;t take much really. Or if they don;t care my GPS could read 19Z IR 0987 5678. I know damn well I am no where near that but if I was stupid and didn't bring my Map and Compass I truly screwed.


PM trust me on this Crypto means SFA when it comes to this....No seriously Trust me!



EDIT: CDN My faith in Spoofing is very very well founded. Is it flawless NO nothing is, is it damn dangerous.....Yes yes it is. I have done some testing with it and have come to know it for the threat it is if you are in the vacinity of a ground station that can do it. That being said I have no knowledge of what it takes to to that to an Aircraft so I can't comment. But I have first hand knowledge of what it can do to ground based GPS system.

 

[aesop081]

It's hard to get into on an open forum....

It is unfortunately so.

 

[HItorMiss]

CDN

PM to you where we can talk more

 

[stealthylizard]

Used both GPS, and map and compass as a seismic surveyor and in seismic exploration.  I trust both to a degree.  We found that we would lose sattelites between 2-4pm almost daily which made the job tedious when recording positions down to 5 millimetres (don't ask me why such accuracy was needed, I just operated the pack).  The compass has limitations.  In some mountain areas, especially around mining operations, the needle would actually spin.  The biggest problem with maps were how current they were (logging roads and cat cut lines really screwed with that).  Even with LIDAR maps, the location of water bodies would sometimes be off a hundred meters.  Great thing about compasses, you never need batteries, and they are fairly easy to learn how to use, but as with any skill, you need to actually use it on a regular basis, or skill fade rapidly sets in.

 

[vonGarvin]

The biggest problem with maps were how current they were (logging roads and cat cut lines really screwed with that). 

True to a point.  Roads, treelines and even some waterways alter over time; however, contour lines rarely do.

 

[Petard]

True to a point.  Roads, treelines and even some waterways alter over time; however, contour lines rarely do.

Agreed, and vital in doing a common sense check I'd say
"Trusting" ones' instruments without a common sense check, usually by using  hard copy map, can cause your mileage to unexpectedly vary.

An instrument slaved to a GPS (e.g. Vector 21 with DAGR) can produce elevation errors (false altitude) relative to those contour lines used in the map data base to compute firing solutions, whether air or ground delvered, resulting in the munitions going long or short depending on the error.

This link helps explain one of devices, called PSS SOF,  used to mitigate this "false" altitude problem, and how this information can be shared jointly.
http://www.dtic.mil/ndia/2007psa_winter/winnefeld.pdf

Another article on how important that is given the increasing number of precision guided weapons becoming available
http://sill-www.army.mil/firesbulletin/2009/Jan_Feb_2009/Jan_Feb_2009_Pages22_27.pdf

Another deadly error can occur if the users don't do a gross error check and too hurriedly just read the GPS data because its always right.
The typical scenario I'm getting at, is with some GPS that resort back to their own last known location if its goes into a dormant or hibernation stage to conserve power. If that same GPS had been used to produce a target grid earlier, and the user prompts the GPS for that target grid, forgetting that it had gone dormant, they might mistakenly read their own grid as the target location. A quick common sense check against a map, preferably by someone that isn't using the GPS, would eliminate that potential.

Wikipedia's explanation covers a number of errors
http://en.wikipedia.org/wiki/Global_Positioning_System

But one that isn't very clear in there, is the error that can come out of the user trying to assist  a system by forcing a grid into their navigation system, possibly because of perceived spoofing or satellite dead zones, or even just as part of rushing initial set up. This possibly could make things worse, if the nav system has a Kalman filter  that may use this location as correct, and include any user induced errors as it resolves the systems location when the GPS signal does become available..


To me, the point of all that is I agree with the the mantracker, you really do need to know how to read map, if for no other reason then as a gross error check of your instruments, or for the inevitable time when you don't have them.

 

[REDinstaller]

And the last time i checked, a map didn't need 2-4 AA batteries.

 

[aesop081]

And the last time i checked, a map didn't need 2-4 AA batteries.

Thats like saying fist fighting the enemy is better because it doesnt require ammunition.

Why dont we just go back to cans and string for communications too......

 

[SeanNewman]

And the last time i checked, a map didn't need 2-4 AA batteries.

Last time I checked, a dismounted soldier didn't require tens of thousands of litres of fuel to go on an op.  Or a fighter jet.

NVGs and flashlights use batteries too, but just like a GPS the benefit you get from them is worth the weight.

 

[REDinstaller]

True, but at least our troops should walk before they run and use a map proficiently before moving on to a DAGR or other GPS device. Then they can fully understand how to navigate when their device of choice fails them in any way.

 

[SeanNewman]

True, but at least our troops should walk before they run and use a map proficiently before moving on to a DAGR or other GPS device. Then they can fully understand how to navigate when their device of choice fails them in any way.

I'm not convinced on the compass and I don't think you need it in order to learn Nav anymore than you need to learn a bow and arrow in order to use a rifle.

As per one of my original posts, it's the fundamentals of navigation that people need to understand, not the compass.

I agree that a map is the basic building block though, and that is the one item that is critical.  If you have a map and navigation fundamentals you don't really need anything else because you understand what direction you're going, you can read the contours/roads, and you can measure distance.

After you have the map and fundamentals though, IMO a compass was last millennium's tool.  That doesn't mean it has no use any more than saying you don't need a knife anymore, but I do not see a compass as mandatory before moving on to a GPS. 

Another analogy would be a fighter pilot.  Is it critical that they learn to fly in a Cessna, or is the basic building block understanding the basics of flight, instrumentation, etc?  I have met ex-Soviet pilots who thought it was silly for a fighter pilot to learn on anything that wasn't a jet...a simpler jet yes but not a prop plane [/tangent].