# Internal Lasing: An Alternative to GPS?



## Kirkhill (10 Nov 2007)

This has been a flea in my bonnet for a while now.

What happens when the GPS goes down?  Is there something better than reverting to map, compass and VPs to maintain situational awareness?  I don't know what is already in the system but it has occured to me that using laser range finders, which seem to be pretty much ubiquitous these days,  to constantly maintain contact with platforms in Line of Sight might be an alternative?  Is this already being done?

If not what would be the disadvantages of using the LRFs to lase ALL contacts - both friend and foe, as well as aerial, maritime and terrestrial as well as fixed terrain.  That would permit station-keeping (vehicle to vehicle distance and formation), positioning (on station with respect to other platforms that know where they are as well as with respect to terrain that is never going to change) and identification (any contact is yellow on the SA screen until it is confirmed as red or blue - if your grid reference pops up on the screen make yourself known to prevent being designated "red")

Aerial platforms like JWACs or Global Hawks, orbiting at high altitudes, would maintain LOS comms over a very large area and the larger the area the harder it is for the enemy to effectively disrupt the radio frequency comms that GPS relies on.  With 3 or more orbiting aircraft of UAVs that know where they are, and that can see and lase ground contacts (and which could consequently be "seen" by the contact even if the commander couldn't actually see an aircraft 100 miles away), and that could communicate with the contacts using the laser, and a the LRF on the contact.

Is this in the works? On the horizon? Unnecessary? Impractical?


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## Franko (10 Nov 2007)

First question: You fall back on basic navigation skills, VP and SA.

Second question: When you lase, you give away any sort of tactical advantage you may have had. Not a good thing. When  you lase, there had better be a round following shortly after.

As for the system you are proposing, how would the information be disseminated? By more lasers? How would any vehicle that is equipped with a laser warning receiver keep up with them all and figure out friend or foe emissions?

Impractical IMHO.

Regards


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## Shamrock (10 Nov 2007)

One problem is that laser is a singly emitted ray.  To maintain 6400 mils of emissions coverage would require a lot of lasers per callsign.  This would also require fairly complicated receiving units -- basically, a third radio with a watermellon sized antenna.  Given the steady flow of lasers to and from each vehicle, this would negate any benefits gained by a laser warning receiver (I'll leave my opinion on that nugget of technology out of this).

Next problem is atmospherics.  Too much water content, smoke, or dust in the air would negate or seriously hamper the effectiveness of the network.


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## Kirkhill (10 Nov 2007)

If you go back to 1916 communications and land-lines as a model, rather than 1940s broadcasting or current multi-node comms - and consider this as fall-back position when the GPS is down, could you not consider a hierarchical, linear model?

TC lases own tp to determine their locstate. Sqn Lases TCs or flanking vehicles or whoever is in sight to get a fix on her/his tps, etc. CO lases Aerostat floating over base and or UAV floating overhead.

Laser Warning Receivers used to determine the direction from which the ranging is being done.

Pulsed lasers used to indicate whether it is a friendly laser or not.  

I can see if everybody is "communicating" indiscriminately using direct LOS comms how signal processing would become a problem, not to mention that the area would be lit up like a Rock Concert.

But is there some way to ensure that if the GPS system goes down you are not forced back to 1940s or even 1916 SA, in which case you are fighting on the same level as your opponents?


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## SeaKingTacco (10 Nov 2007)

You would be better off putting a Ring Laser Gyro in each vehicle as part of an onboard Inertial Naviagtion System... Of course, it would be just cheaper to rely on map reading and compasses.


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## Michael OLeary (10 Nov 2007)

Kirkhill said:
			
		

> What happens when the GPS goes down?



Can you define this better?  Are we talking about a conflict scenario with a belligerent capable of bringing down the satellite network?  Or one that can sufficiently disrupt the comms component to compromise the effectiveness of GPS within an AOR?

At what point does an element, individual or organizational, switch to your proposed backup?  What happens if not all are affected by the GPS blackout, how do you perceive integration between the systems?

If the hypothetical belligerent can interrupt GPS technology, wouldn't a complicated laser based alternative, with complex information sharing built into the pulses, be equally susceptible to technology attack?  Your 'solution' is likely to be more complicated and more expensive than the system it would be the back up for.

Sometimes, being prepared to fall back on the simple proven lower-tech methods is the best first alternative.


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## a_majoor (10 Nov 2007)

This seems to be pile on Kirkhill day. 

Sorry, Kirkhill, but an even simpler objection than the ones already raised is the extreme line of sight nature of lasers. Even light vegetation would stop lasers, so anyone behind a bush, sitting in the low ground or behind or inside a building would e cut off from the system. The only partial work around would be to have some sort of system in the sky; a sort of AWACS sending laser pulses from the air to the ground and reading people's reflections to get their position (Assuming they are in line of sight and not protected by overhead cover or concealment).

Of course you would need a real AWACS to handle the laser emitter and receiver array, process all the data and send it in encrypted format to the end users, and a constant CAP to protect it, and clear weather so the laser actually works, etc. It would probably be much simpler and cheaper to have a ring laser gyro "inertial platform" on every piece of equipment to get the same effect.


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## Kirkhill (11 Nov 2007)

a_majoor said:
			
		

> This seems to be pile on Kirkhill day.



No worries....every now and then fingers run ahead of brain.  

As to all the salient points brought up by all concerned... WOW.  Running 2 for 2 just now considering the MGS-FOO calamity.  Oh well

However, regardless of the specific issues, which I am clear on now, I can't help but feel that you are exceptionally vulnerable to a GPS takedown.  And that there should be some sort of viable alternative other than reverting to "steamboat" drills.

Without knowing all the details of the system it seems to me that GPS is ultimately an RF beacon based system that can be countered by either taking out the "beacon", the satellite, or by blocking the RF transmission.  While there aren't many states that can organize a long-lasting takedown of the beacons and disrupting the system globally, couldn't a local tactical or operational advantage be achieved by jamming?

If the issue is that the system is being jammed then aren't other means of communications likely to be jammed as well?  We used to keep landlines on hand because they were likely to work even when the radios didn't, even if it reduced the timeliness of information transfer because you effectively had to run to find a telephone and then wait for the information to percolate up the pyramid and back down.  

I am wondering if the laser, and maybe not the same lasers as the Range Finders, couldn't be used partly the way the old heliograph was used, or the way the Aldis Lamp  was used, effectively they transmit the dots and dashes of Morse Code to relay messages.  I am not sure, but I believe the Navy may still use the Aldis Lamp for Ship to Ship comms in periods of radio silence or for evolutions like Jackstay transfers and Replenishment At Sea.  I understand that there might be atmospheric conditions, and vegetation conditions that would limit or preclude their use, and therefore they would not be a replacement, they may only be a poor second cousin to the all-singing all-dancing comms currently available when all is functioning properly.  But do they offer an alternative to jammed radios and GPS systems, landlines and runners?

Also, with respect to location using LRFs it seems to me that they offer great opportunities for developing back-bearings and triangulating own position from known features.  GPS was particularly valuable in Iraq and Kuwait because features were few and far between.  The GPS beacons effectively became the features on which the triangulation occured.

The Navy has used "station-keeping", maintaining distance and bearing, as a means of keeping track of its charges so that while everybody SHOULD be independently navigating, not everybody HAS to independently navigate.  The same goes for the Air Force moving formations.  Only one central unit needs to know where it is and everybody else keys in on it.

My thought is that if the GPS goes down then the list of "features" available for triangulation in the field would include not just physical features but UAVs, Aerostats, Aircraft, Ships at Sea or even other vehicles.  If even one vehicle/platform/feature is known with any certainty then that provides a fixed reference for double-checking the individual navigation of everybody else.

But....presumably this isn't a problem....

Regards and Cheers, Chris. 

PS - here's one company offering a Line of Sight Laser Communications Network  --- http://www.advantex.uk.com/index.asp?id=32

PPS - WRT the need for an AWACS signal processor - not really - Don't you just need a giant mirror in the sky with known position that guys on the ground could lase on in order to get a fix on their position?  Pretty much like taking back-bearings on the mountain tops round Bragg Creek to fix your locstate.


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## rz350 (21 Nov 2007)

Kirkhill said:
			
		

> PPS - WRT the need for an AWACS signal processor - not really - Don't you just need a giant mirror in the sky with known position that guys on the ground could lase on in order to get a fix on their position?  Pretty much like taking back-bearings on the mountain tops round Bragg Creek to fix your locstate.



Why not issue a sextant then? Have them use their last known elevation. (from before the GPS broke down) and just take readings from the navigational stars. You would need to know your elevation to use a hovering mirror and a laser as well. The sextant has perfect EMCON. (since its pure passive) and is very difficult to jam. (unless your God)


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## I_am_John_Galt (21 Nov 2007)

SeaKingTacco said:
			
		

> You would be better off putting a Ring Laser Gyro in each vehicle as part of an onboard Inertial Naviagtion System... Of course, it would be just cheaper to rely on map reading and compasses.



+1 (to both parts) ... although I'd bet that they aren't THAT expensive ...


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## Matt_Fisher (6 Dec 2007)

On the dismounted side of things, this issue is being looked at through the use of 'Dead Reckoning Modules' 
http://www.ssec.honeywell.com/magnetic/datasheets/drm5.pdf


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## Kirkhill (6 Dec 2007)

Matt: from the Honeywell data

Typical accuracy 1% to 2% distance traveled
Digital compass azimuth accuracy better than 1°

After a 10km march that would equate to 100-200m off target  and 18 mils off line.

Is that close enough?

While we are pondering that I wonder if rz350 might not have a point.   But I am not sure that we need to issue sextants.  With all the dialed in range-finders and gun-sights out there do you need to issue sextants? Or is it possible to use the, for example, the CROWS, to get a Sun-Sight, Moon-Sight, Polaris, Venus etc?  After all most celestial navigation is about calculation and comparison to charts.  Most of that can be embedded in a chip can't it?  

It might give a whole new meaning to "shooting the sun".


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## X-mo-1979 (6 Dec 2007)

Matt_Fisher said:
			
		

> On the dismounted side of things, this issue is being looked at through the use of 'Dead Reckoning Modules'
> http://www.ssec.honeywell.com/magnetic/datasheets/drm5.pdf



The standard issued GPS does dead reckoning as well.

kirkhill,
Your basing your argument for your idea,(as it seems to me anyway)on the GPS being the sole navigator of the btln,platoon,c/s,dismount.Which it never will be.Nothing takes the place of resorting back to the tried and tested map recce,paying attention to your surroundings,and then referring to you map from time to time.No soldier should have their map in their face ,or they are totally inneffective at what ever they are doing.
If you do a proper map recce you can stick the map away for reference later.

Also the multiburst laser would make using the tacnav quite difficult.How would we know if it was EN lazing or not.True the system pics up three types (target des,eye safe,non eye safe)however when a laser hits my vehicle I'm looking for who's engaging me tout quick. 

If I ever see another stupid box put into my already crammed crew compartment...I'll know who came up with the idea anyway.

Not effective.

Maybe we should save the millions and take the 20 minutes to teach soldiers how to commit a leg/trace to memory.
"...after the wooline bordered by a stream theres a steep incline where I will make a fireposition,from there..."


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## Kirkhill (6 Dec 2007)

X-mo-1979

You don't need to worry about me supplying the box  ;D   I am an uninformed civilian through and through.

I understand what you are saying about using the GPS as an adjunct to conventional navigation.   My concern was based on two things: one was the successful conduct of operations in a "featureless" landscape like Kuwait and Southern Iraq which was largely possible due to the GPS; and the other was a tendency that I have noted amongst the younger generation to look for buttons to push rather than relying on their own capabilities.


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## a_majoor (6 Dec 2007)

Kirkhill said:
			
		

> a tendency that I have noted amongst the younger generation to look for buttons to push rather than relying on their own capabilities.



Put some entertaining map and compass orienteering on Youtube and we will probably see millions of people learning the art.......


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## X-mo-1979 (7 Dec 2007)

Kirkhill said:
			
		

> X-mo-1979
> 
> You don't need to worry about me supplying the box  ;D   I am an uninformed civilian through and through.



And thats usually who develops it  and installs it. ;D


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## chrisf (7 Dec 2007)

A thought...

Anything jamming a GPS signal over a wide enough area to make it a viable threat is going to be VERY noticable to EW. And will in short order be the victim of either an artillery or air strike. No problem if you've got air superiority...

If you're on par with the enemy for air capability, then anything jamming a GPS signal would still obviously be a high priority target, but so would your alternative to GPS... so it would have to be well defended.

If your enemy has air superiority, you want to eliminate your electronic signature. SAS being run over a radio net is out of the question.

EW is a terrifying thing that everyone forgets about... but for a few bucks at rat shack, you could easily build a simple yet effective EW suite. For a few more bucks (And not even that much more) you could build an extremely effective EW suite.


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## Harry Potter (23 Jan 2008)

silver said:
			
		

> We can lase bad guys pretty indiscriminately because we don't care what we do to them physically.



Actually, no you can't.  At least the indiscriminate part.  A bit off topic but lawyers are all over that one, LOAC implications and all.  It is one of the main issues regarding the use of laser dazzlers.

Back to the main topic.  WRT using EW against GPS, keep in mind that GPS functions on a frequency band that is very directional.  It makes it quite challenging to jam a single GPS receiver and nearly impossible to jam them all within a footprint that would make it worthwhile for the enemy.  If the capability exists, it will be reserved to confuse the guidance system of a GPS guided weapon, not against ground troops.


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## Old and Tired (30 Jan 2008)

I've been following the discussion for a awhile.  Here are a couple of things that might help.

(MODS - ALL INFO is from open source)

Kirkhill

Your fears/worries are very, very well founded.  GPS is not the end all be all of navigation.  It is susceptable all kinds of nafarious activities.  Contrary to popular belief, the Time signal transmitters on GPS satelites are not directional.  That's what makes the system work in the first place.  Your GPS receiver reads these signals from multiple point sources, it knows where the satilites are by the embedded ID data that they send.  The GPS receiver compares the the receive signal time stamp with it it's own internal clock and those of the other sats that it has received.  It calculates some basic trig and presto here I am at GRIP such and such.

Can GPS be JAMMED.  Simple answer is yes. Over a Wide area, probably not.  Too resource and energy intesive and as has been pointed out, you would light yourself up like a Christmas tree.  Over short distances or areas, yes it can and has been done.  There are many commercial devices currently on the market that will achieve this.  RADIO SHACK, as mentioned carries most if not all that is required.  Any technologically knowledgable advisary can do this on a low level.

A bigger threat is Spoofing or MEACONing.  I won't explain these here, Google is your friend on that one.  Bottom line is that these ideas are not new (Think WW2 and the Wizard War as Churchill called it)

LASER system. BAD BAD idea.  A great many reasons have already been made, difficulty, cost etc, etc.  Two more to pile on.  1  Autonomus or Semi-Autonomus Vehicle defence systems that are currently employed by many nations.  Last thing I'd want to do is LASE a Callsign to my flank and have him light me up in return.  2.  Power requirements versus power avalaible in most vehicles.


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## Theweatherman (30 Sep 2008)

Personally I can't speak from experience with military gps and frankly I don't know what the difference would be between that and the gps I have had experience with while working at my current job. I didn't see this mentioned yet so I think it is worth bringing up; solar storms can also disrupt the gps network. Also we have also had problems before because another gps base station's radio was set up within range of our rover and was on the same channel as our radio was.


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