Slashdot Mirror
Military Tech: GPS and Networking
king of birds writes "The New York Times has an interesting article on the present military use of GPS. While some units have rather modern system that can graphically display locations of other troops, others rely on 10-year-old 5 channel receivers. Kind of odd when I can 12 channels on my civilian model (with admittedly lower spatial accuracy)." aaronvegh writes "From the Canadian Press, a story about how a US infantry division uses a system of transponders and servers to track friendly and enemy units, from the headquarters to inside individual tanks. Talk about total information awareness! No friendlies were harmed in the making of this story."
Public Key Infrastructure & Cryptography
Among a host of other military technologies that are in place to guarantee the authenticity of a user
WW II: 21,000 (16%)
Vietnam war: 8,000 (14%)
Gulf War: 35 (23%)
Afghanistan (2002): 4 (13%)
The difference today is instant communications. And the small number of total casualties allows the media to focus on each death.
Many military radios can do frequency hopping - changing frequencies many times a second. So unless you have a similar device AND you know the algorithm, AND you know the starting frequency, AND you know when the radios were turned on...
Come on, I know someone works in a Comm MOS and can 'splain it better ;-)
A pilot, in those days, was the only unfettered and entirely independent human being that lived in the earth.-Mark Twain
A big focus of the project is open hardware and software - something that's sorely lacking in APRS. Take the MIM, for example. It's a pretty clever little telemetry transmitter, but it sells for $79. Seems pretty excessive for a circuit board with a PIC and some support circuitry. No source code is provided, either. I'm working on something similar, but it'll be completely open source, provided under the BSD license. Source, CAD drawings, foil patterns, and all that stuff will be published for anyone to duplicate or modify.
Many military radios can do frequency hopping - changing frequencies many times a second. So unless you have a similar device AND you know the algorithm, AND you know the starting frequency, AND you know when the radios were turned on...
I use to work on military communications. The version I worked on switched frequencies about 10,000 times a second. That was ten years ago. Not only is this harder to track, but even more importantly it's harder to jam. Keys were changed daily.
From the article:
The new system will also track all 12 G.P.S. satellites in each hemisphere at once. The old units can only track five satellites at once, and signals from four satellites are required to establish a three-dimensional position. In addition, current G.P.S. receivers are somewhat vulnerable to enemy equipment that beams false G.P.S. signals to indicate the wrong location, a technique known as spoofing.
Here's the thing: the article is correct about the PLGR needing four locked satellites to establish a three-dimensional position. However, a PLGR can also establish a two-dimensional position with two locked signals and one intermittent one. The important part here is that the PLGR's most common use (determining position for individual soldiers and vehicles) doesn't need a 3D position. Your position (including elevation) can be plotted on any map using only two coordinates. 3D positions are only important for aircraft, air defense, and artillery. And for the most part, those guys aren't using PLGRs. Oh, and PLGRs can track up to 10 satellites.
This corrective post brought to you by a US Army Cavalry Scout. (None of this information, by the way, is classified or restricted. The reporter just didn't check sources very well.)
Arr! The laws of physics be a harsh mistress!
Plus the old ones [fas.org] have such a crappy user interface that you accidentally drop bombs on your own troops. Apparently, its a 14 step process to replace the battery, and in the confusion of battle mistakes are made. The same display for "current" location is used for "target" location, and in Afghanistan they dropped some on themselves.
Okay, let me dispel several fallacies here. First, the user interface, like any other, is only crappy if you don't learn how to use the device. Once you know how the device works, you don't have to think to use it. Second, it's a four step process to replace the battery: turn the unit off, replace the battery, turn the unit on, re-sync. Six button presses in total. If you know how to use the unit. Third, PLGRs report THEIR OWN POSITION. If you want to call arty or air support on a target you have to PLOT THE POSITION OF THE TARGET ON YOUR MAP MANUALLY. Anybody dumb enough to give their own position as target coordinates for an air strike deserves to have a bomb dropped on them.
Arr! The laws of physics be a harsh mistress!
we have a 'civ' model of Germen Summit GPS. It has survived over a year of constant abuse in our tool box, and has been dropped off 3 different towers that were over 100' tall. Then we dropped it off our main tower, 500'. The batteries popped out and went somewhere but it still works! Made a big THUD and slight crater in the ground....
I love working with a wISP, its sooo much cooler than boring old regular ISP work...!
Slow? resource intensive?
GPS uses triangulation, essentially, although it's a lot easier since it sends out a timestamp. To triangulate a unit, you would have to have 3 stations be time-synchronized and all would have to know they heard the same signal -- which is undoubtedly coded making it EASIER to know it was the same.
In other words, tank A sends out an encrypted digital message of "here is my location". If 3 stations hear the signal and timestamp it to the nanosecond, they can them compare the signal--without knowing what it actually broadcast--and tell it was the same broadcast. Using the time data and and the exact location of each station, it's a simple matter to plot the location of the transmission. The farther apart the 3 stations, the better the accuracy. More stations would lead to more accuracy, plus you'd couldn't shut it down by bombing a single tower as long as 3 remained.
This would essentially be a reverse-gps. It's only resource-intensive and slow if you have a single unit driving around with a directional antenna, like the FCC did to locate pirate stations. If you can synchronize the clocks and timestamp signals accurately, it's almost trivial to pinpoint the location.
I have used both military and civ models.
Civilian models are designed to be lightweight, waterproof, and reasonably accurate. Some will average selective availability to get a statistically more accurate reading. A 12-channel chip is the size of a dime. The newer ones with integrated map data are excellent.
Military models have decryption software (basically a 3DES chip, I believe) which can listen to the encrypted channels broadcast by the birds but from what I understand, the MAIN DIFFERENCE is that military models have a more accurate clock than the civilian models. Because of this, even with SA disabled, they get triple the accuracy with 7 fewer channels.
Sorry about not formatting this link.
http://www.shai.com/papers/IITSEC-02-FBCB2.pdf
Interestingly enough, the Army's most powerful tanks, the M1A2, don't run FBCB2, they run the older and incompatible system which I believe is called IFIS. The 3rd Division in Iraq had M1A2s with IFIS and the recently deployed 4th is outfitted with FBCB2. The 4th is considered the Army's most "wired" division.
this sig deleted by another sig
Most of these things are designed with LPI (low probability of intercept) in mind - they are nearly impossible to detect with even the best equipment - now consider the technology that our opponents have and it comes out to be 0 risk. The benefit of knowing where your forces are, to prevent fratricide, far outweigh the astronomical odds of having your transponder tracked.