Author Topic: GPS - Trust / Don't Trust  (Read 26790 times)

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aesop081

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Re: GPS - Trust / Don't Trust
« Reply #25 on: September 06, 2010, 19:05:46 »
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.

Offline George Wallace

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Re: GPS - Trust / Don't Trust
« Reply #26 on: September 06, 2010, 19:11:47 »
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.   

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Offline Petamocto

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Re: GPS - Trust / Don't Trust
« Reply #27 on: September 06, 2010, 19:14:10 »
...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.
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Offline George Wallace

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Re: GPS - Trust / Don't Trust
« Reply #28 on: September 06, 2010, 19:18:18 »
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.
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Offline BulletMagnet

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Re: GPS - Trust / Don't Trust
« Reply #29 on: September 06, 2010, 19:27:46 »
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.




« Last Edit: September 06, 2010, 19:34:35 by BulletMagnet »
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aesop081

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Re: GPS - Trust / Don't Trust
« Reply #30 on: September 06, 2010, 19:40:01 »
It's hard to get into on an open forum....


It is unfortunately so.

Offline BulletMagnet

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Re: GPS - Trust / Don't Trust
« Reply #31 on: September 06, 2010, 19:47:34 »
CDN

PM to you where we can talk more
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Offline stealthylizard

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Re: GPS - Trust / Don't Trust
« Reply #32 on: September 08, 2010, 21:01:34 »
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.

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Re: GPS - Trust / Don't Trust
« Reply #33 on: September 09, 2010, 05:46:32 »
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.
So, there I was....

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Re: GPS - Trust / Don't Trust
« Reply #34 on: September 09, 2010, 22:37:43 »
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.

Offline Tango18A

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Re: GPS - Trust / Don't Trust
« Reply #35 on: September 10, 2010, 00:07:19 »
And the last time i checked, a map didn't need 2-4 AA batteries.

aesop081

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Re: GPS - Trust / Don't Trust
« Reply #36 on: September 10, 2010, 00:41:20 »
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......

Offline Petamocto

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Re: GPS - Trust / Don't Trust
« Reply #37 on: September 10, 2010, 07:03:27 »
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.
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Offline Tango18A

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Re: GPS - Trust / Don't Trust
« Reply #38 on: September 10, 2010, 08:26:53 »
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.

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Re: GPS - Trust / Don't Trust
« Reply #39 on: September 10, 2010, 11:31:36 »
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].
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Offline Tango18A

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Re: GPS - Trust / Don't Trust
« Reply #40 on: September 10, 2010, 16:50:36 »
And how many airlines are looking for Ex-Soviet fighter pilots to fly their passengers around??? The navigational equivalent to a bow and arrow would be a Sextant. Which for some reason is still used by Air Navs. Satellites can fall from the sky, but that big piece of iron floating inside the earth... well when it fails it just won't matter.

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Re: GPS - Trust / Don't Trust
« Reply #41 on: September 10, 2010, 17:35:58 »
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.

Even though I have a GPS for my car, I always do a map recce. It's a certain source of amusement for my wife, and wonderment for my civilian friends.

I suppose the wise thing to do is to never trust a single source of information.
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Offline Petamocto

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Re: GPS - Trust / Don't Trust
« Reply #42 on: September 10, 2010, 17:42:59 »
Even though I have a GPS for my car, I always do a map recce.

Mike,

And I think you've hit a perfect point there.  I'm as much of a GPS believer as a person can be, but still not silly enough to rely entirely on it.

The key fault with the civilian versions is that if a person only cares about how far until their next turn, they risk not being able to visualize where they actually are on the ground.  Numerous times I have entered an address on my Garmin Nuvi only to get there and have it be nothing at all like what it's supposed to be, but due to understanding what roads are where I can find it.

A person who doesn't do that map recce and doesn't have a built in compass is just going to stop at the side of the road and cry, or have to start making cellphone calls and embarrassing himself.
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Re: GPS - Trust / Don't Trust
« Reply #43 on: September 10, 2010, 19:57:22 »

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. 


Navigating in close complex terrain, especially thick forest or jungle, where GPS signals may be attenuated to the point they're not useable, and there is no line of sight to see much of any contours or landmarks, I'd say a compass is very useful.
And for supported arm call for fire a compass is a very easy thing to use to get a a bearing to adjust off of

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Re: GPS - Trust / Don't Trust
« Reply #44 on: September 10, 2010, 21:20:23 »
But what you are discussing is a very specific arc of employment, and yes I still carry my compass for just such an occasion (or sitting in a trench and wanting a static bearing).

That is the same as having a knife for doing something and a gun for doing something else.
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aesop081

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Re: GPS - Trust / Don't Trust
« Reply #45 on: September 10, 2010, 22:33:13 »
Which for some reason is still used by Air Navs.

Stellar navigation is no longer taught at the school in Winnipeg and has not been for years. GPS and INS.........

Offline Oldgateboatdriver

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Re: GPS - Trust / Don't Trust
« Reply #46 on: September 11, 2010, 07:56:29 »
Simple truth is never trust a single source for any information needed to carry out a task.

Many moons ago, there was a picture on the walls of the DC/FF school in Halifax of one of the big ferries that cross the English Channel high and dry on the beaches near Calais. Now the mariners that run those things are like bus drivers: they know their route by heart. So how did it happen? Simply, the input wire that connected the GPS feed to the electronic map got loose - and the map automatically went into dead reckoning mode. It just forgot to compensate for the five knots currents found in the area. By the time the captain felt a "weird" vibration, made his way to the bridge, looked at the radar screen and figured out where he really was, it was too late.

That is why naval captains insist to this day: never two fixes in a row using the same source in coastal waters - check each source against the others all the time. And why the pilots on warships still try to put in a good astro-fix once a day in mid ocean - just to feel comfortable with the GPS data.

Offline Jungle

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Re: GPS - Trust / Don't Trust
« Reply #47 on: September 11, 2010, 08:18:30 »
Navigating in close complex terrain, especially thick forest or jungle, where GPS signals may be attenuated to the point they're not useable, and there is no line of sight to see much of any contours or landmarks, I'd say a compass is very useful.
And for supported arm call for fire a compass is a very easy thing to use to get a a bearing to adjust off of

I'm a fan of the GPS, but I was well-trained in the use of the map and compass; some good ways to train people to work with a map is to give them a bearing and a one-grid square map of the destination. We did this at night in France; reading the map (the destination-only grid square) and everybody's SA IOT find the TGT become extremely important.

During jungle warfare trg, we were sent out with no map, but a set of bearings, distances and destination landmarks for the route. Pacing rapidly becomes your best friend...

Modern GPSs are much more effective in complex terrain. I use the Garmin Oregon, and I rarely have reception problems with it.
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Re: GPS - Trust / Don't Trust
« Reply #48 on: September 11, 2010, 22:03:02 »
Simple truth is never trust a single source for any information needed to carry out a task.


And that, gentlemen, is the best line of this entire topic.

What's that old quote about guns, comms, flashlights and riflemen....? Oh yeah:

"2 is 1. 1 might as well be none."

"Return with your shield, or upon it."

Offline Petamocto

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Re: GPS - Trust / Don't Trust
« Reply #49 on: September 12, 2010, 07:12:22 »
The quote "2 is 1 and 1 is none" is I believe better attributed to one of the awesome instructors in GI Jane.
"Do what you feel in your heart to be right - for you'll be criticized anyway." - Roosevelt