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Us Military Tests Jamming Of Gps?


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cruise missles and drones and such use gps, as do military units trying to find their way in unfamiliar territory. Being able to jam the signals would be a significant capability. Of course, there already is SA, which can be turned on whenever they like. Military grade GPSs can receive a signal that is accurate even when SA is turned on.

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Really something that's not new but this time it's being done on a much larger basis and test like this are needed to determine actual outcomes and issues if ever the system was lost or closed down for all the wrong reasons.

 

Basically looking at the affects and deriving continency plans if ever things became real.

 

One of the reasons why SA was discontinued was that there is now a capability to regionalize a SA type of inaccuracy. Also in the past SA was required to cloud the C/A code as C/A was required to acquire the P/Y code, so simply turning of C/A (depriving civil users) also basically deprived the military signals. As part of discontinuing SA they worked out a way to acquire the P/Y code without even needing the C/A code.

 

Cheers, Kerry.

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Really something that's not new but this time it's being done on a much larger basis and test like this are needed to determine actual outcomes and issues if ever the system was lost or closed down for all the wrong reasons.

 

Basically looking at the affects and deriving continency plans if ever things became real.

 

One of the reasons why SA was discontinued was that there is now a capability to regionalize a SA type of inaccuracy. Also in the past SA was required to cloud the C/A code as C/A was required to acquire the P/Y code, so simply turning of C/A (depriving civil users) also basically deprived the military signals. As part of discontinuing SA they worked out a way to acquire the P/Y code without even needing the C/A code.

 

Cheers, Kerry.

Does that come in english??? :blink:

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"Come in english" :blink: think it would make a difference :o

 

Maybe "appliance" langauge might have been better, much like say the way electric toaster or electric tootbrush instructions are worded.

 

Maybe some should be simply limited to pushing buttons, some of the "real" answers might be a shock.

 

Cheers, Kerry.

Edited by Kerry.
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"Come in english" :o think it would make a difference :blink:

 

Maybe "appliance" langauge might have been better, much like say the way electric toaster or electric tootbrush instructions are worded.

 

Maybe some should be simply limited to pushing buttons, some of the "real" answers might be a shock.

 

Cheers, Kerry.

Ummm yah for us laymen it would make a difference. Not only was that terse (and it looks like it was toned down by your edit) but not all of us speak tech geek at that level and would still like to understand it at a level more easily digestible.

 

This is not an engineer's forum.

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Smartest thing we Americans did was to do away with SA. Now the whole world is getting "free" very accurate position fixing. It's like a pusher giving away free drugs. They're not going to spend the money to put up satellites. But we can turn off at any time when we want during a war and use it for our own arms. What more can you ask for?

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"Come in english"  :D think it would make a difference  :o

 

Maybe "appliance" langauge might have been better, much like say the way electric toaster or electric tootbrush instructions are worded.

 

Maybe some should be simply limited to pushing buttons, some of the "real" answers might be a shock.

 

Cheers, Kerry.

Ummm yah for us laymen it would make a difference. Not only was that terse (and it looks like it was toned down by your edit) but not all of us speak tech geek at that level and would still like to understand it at a level more easily digestible.

 

This is not an engineer's forum.

Half of kerry's posts are filled with techno babble and usually no usable information. Leaving you wondering if he said anything at all. :o The other half are condescending spiteful quips of self-promotion. Well maybe more than half. :blink:

 

 

He probably copies and pastes most of the techno stuff anyway. ?!Plagiarism!?

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Maybe leatherman would like to translate then :blink:, really quite a basic function of the system but if not then go back to reading the toaster instructions, might be more constructive.

 

So do you want to be button pushers or try and understand why the signal you now use can be flicked without affecting the other side. Now that hasn't always been possible but leaterman here is going to tell us why :o

 

Cheers, Kerry.

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Maybe leatherman would like to translate then :o, really quite a basic function of the system but if not then go back to reading the toaster instructions, might be more constructive.

 

So do you want to be button pushers or try and understand why the signal you now use can be flicked without affecting the other side. Now that hasn't always been possible but leaterman here is going to tell us why :o

 

Cheers, Kerry.

You must think you're witty. A legend in your own mind. I didn't suggest that I would translate for you. You should be able to do that. :blink:

However you have not provided any useful information. When others ask for a layman explanation you respond with sarcasm. Which, logically, leads us to believe that you don't understand what you're posting. Copying and pasting?! :D

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Maybe leatherman would like to translate then :blink:, really quite a basic function of the system but if not then go back to reading the toaster instructions, might be more constructive.

 

So do you want to be button pushers or try and understand why the signal you now use can be flicked without affecting the other side. Now that hasn't always been possible but leaterman here is going to tell us why :o

 

Cheers, Kerry.

Yes; as noted by GEO*Trailblazer 1's link with no thanks to you.

The real point between myself and Leatherman, was your answer was a no answer to laymen. It was however, designed to elicit a response of "Huh?", with the followup smackdown when people can't seem to keep up with you.

 

You were asked in a humorous way to flesh out your answer and you responded back with sarcasm. Not only was your back-handed slap about button pushers and toaster instructions unappreciated, you lost some credibility to be helpful as well.

 

Perhaps you can use this as a guideline:

If you can't be part of the solution, don't be part of the problem.

 

Regards,

TL

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Really something that's not new but this time it's being done on a much larger basis and test like this are needed to determine actual outcomes and issues if ever the system was lost or closed down for all the wrong reasons.

 

Basically looking at the affects and deriving continency plans if ever things became real.

 

One of the reasons why SA was discontinued was that there is now a capability to regionalize a SA type of inaccuracy. Also in the past SA was required to cloud the C/A code as C/A was required to acquire the P/Y code, so simply turning of C/A (depriving civil users) also basically deprived the military signals. As part of discontinuing SA they worked out a way to acquire the P/Y code without even needing the C/A code.

 

Cheers, Kerry.

Having read your posts in this thread, I can now say that I totally agree with and understand your sig line.

 

Still somwhat techincal, but a little more toaster-like, an explanation of P/Y and other GPS details can be found here.

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Considering I have spent 20 of my 27 years in various forms of schooling, I'd like to comment that there are a few classes of people in this world when it comes to education.

 

The first and easiest to get out of the way is the doofus. They don't want education, they don't need education, they simply want things to work (dadgum the cost or consequences). They simply go on what they find and sometimes it suprises them to discover something (that someone could have taught them half a lifetime ago if they'd only listened). Sufficed to say, they couldn't teach anything to anyone if their life depended on it.

 

The second is the layperson. Their expertise is often limited to a single topic of interest to them, but they still have a much broader understanding of the world around them than the doofus. They are interested in learning enough to understand things, but only concern their expertise of a topic to a specific area of scrutiny. They can often relay their expertise to someone else, but it may come out confusing to another layperson of highly different expertise.

 

The third is the worldly student. This person is a jack-of-all-subjects. They may or may not have a specific expertise, but they have a better grasp than the layperson on more subjects at a deeper level. Because they are so varied in their knowledge base, they can often visualize a discussion or topic from various other angles. One of those angles is more likely to be closer to the expertise of the person trying to understand and as such, they can relate to many other worldly students, laypersons, professors, but not doofuses.

 

The final is the professor. Professors delve deeper (and often broader) than wordly students but because they get a little too involved in the minutia, they begin to lose touch with reality. Their ability to teach their level of understanding often requires being very close to the professors own level in the subject to begin with. Their ability to relate their topic by simile or some other means of approaching the topic is almost non-existant. Worldly students may pick up on the professor's teachings, but few laymen can relate.

 

Ok, now, Kerry. obviously might fall into the latter category. He's not "cut'n'paste", because certain other aspects of his comments (using the word "affect" = "feeling" instead of "effect" = "result") are consistently in his posts. His obnoxiousness about his posts is a personality flaw not related to his rank above.

 

I like to think of myself in the "worldly student" area. As such, here's my translation of what Kerry. was saying earlier that no one could understand:

 

One of the reasons why SA was discontinued was that there is now a capability to regionalize a SA type of inaccuracy. Also in the past SA was required to cloud the C/A code as C/A was required to acquire the P/Y code, so simply turning of C/A (depriving civil users) also basically deprived the military signals. As part of discontinuing SA they worked out a way to acquire the P/Y code without even needing the C/A code.

 

GPSrs need to find the "start" of every time signal message that comes in from the satellites. There are 2 kinds of GPS signals: a signal that can be synchronized very quickly (C/A) and a very long and slower to synchronize signal (P-code). If you then encrypt P-code, you get Y-code...so Kerry. just calls that (P/Y). We use C/A in our non-military GPSrs.

 

SA introduced glitches in the broadcast of the C/A signal, so it was harder for your GPSr to understand the "starts" and therefore harder to get a clean lock of the satellites necessary to pinpoint your position (Meanwhile P/Y signals were unaffected). It's as if you were driving down the road blinking your eyes...you get a general picture of the road, but you will probably cross all over the lines doing so. Either way, SA is off now because the uses of GPS for emergency and commerce far outweigh the military need and at the same time the military had created a localized C/A signal jammer.

 

Now, as I said before, P/Y is a long, slow signal to find the "start" of, so that you can use it. BUT, if you listen to both the C/A and P/Y at the same time, you can cheat and jump into the middle of the P/Y signal and begin using it for navigation. *Most* military GPSrs use this technique. Newer military receivers (new = 9/2002 and on) have advanced software that can understand the P/Y code in the middle without the aid of the C/A code (there are also new technology that can ignore a ground-based C/A jammer). Neither of these are the norm yet, though, so for now SA will definitely stay off and local jamming will probably not be used (because of the C/A reliance from the older military GPSrs).

 

Hope that helps.

 

PS - Most of my info came from here:

http://gge.unb.ca/Resources/Iraq_and_GPS.html

Edited by ju66l3r
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Excellent explanation. Thanks!

You're welcome. But I guess I should fix something. SA is more of a shift in the C/A signal (not like blinking, but like someone else turning the wheel a little bit on you repeatedly).

 

For example, if you were supposed to get a specific number from the satellite, say 10. Without SA, you get:

 

10, 10, 10, 10, 10, 10...

 

Then SA added into it might send you:

 

10, 9, 10, 7, 7, 8, 11, 10...

 

which if anyone using a GPSr before SA was off might recognize as the jittery walk or "jumpiness" of the resulting coordinates. It didn't mess with the start of the C/A signal so much as the content.

 

Just a correction, either way the rest still stands, since SA is now off, it doesn't now matter much what it was doing to interfere.

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I grabbed the following from an older website:

 

Military Use: Precise Positioning Service (PPS) Receivers are for military use. They are military equipment and require encryption keys to operate at their full level of accuracy. PPS receivers track the precise (P) code on two frequencies in order to correct for delay of the signal through the upper atmosphere (ionosphere) 

 

Civilian Use: Standard Positioning Service (SPS) Receivers are for civilian use. they are designed to track the coarse-acquisition (C/A) code broadcast by the satellites. The SPS receivers provide 100 metre accuracy under good satellite geometry. 

 

Military uses at least 2 frequencies, whereas Civilian uses only one very jammable frequency.

 

The military could have a setup within senitive areas, that can jam or modify signals of civilian GPS units that are too close. Terrorists are less likey to jam the military P-code, but i guess they could generate alot of noise in those frequency ranges that the military uses, to make it hard for military GPS units to work, like in guided missles.

 

There has been a problem in the past where alot of the military people, have had to buy Over The Counter civilian GPS units, because there were not enough military GPS units, and these are effected by military jamming also.

 

---------------------------------------------------

 

I have been interested in how GPS works for many years, and I know some electronics.

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Oh, one other thing...to the original question and some of the answers:

 

The point was brought up that you could jam a GPS-guided missle. Well, the military has already thought of that. All GPS-guided missles also have inertial sensors. Their on-board electronics know how high and how far they were supposed to go even without GPS guidance. Regardless of jamming, we wouldn't want our missles to stray just because the weather made them drop a satellite lock. :blink:

 

GPS jamming of the C/A band is more to keep troops/movement/intel reporting disoriented. It's harder to point a long-distance non-GPS missle/mortar correctly when the guy giving you the enemy position has to go back to compass readings and map legends.

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Thanks to all that took the time to give a simple civil answer.

 

Please remember the guidelines state:

 

Respect: Respect the guidelines for forum usage, and site usage. Respect Groundspeak, its employees, volunteers, yourself, fellow community members, and guests on these boards. Whether a community member has one post or 5,000 posts, they deserve the same respect.

 

Personal Attacks and Flames will not be tolerated. If you want to praise or criticize, give examples as to why it is good or bad, general attacks on a person or idea will not be tolerated.

Edited by CO Admin
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Frankly some do need to practice what they preach especially those have have some problems in understanding what's basically a simplistic outline. If some really want a story then asking for it in "english" isn't the way to go about it.

 

Hindsight is a wonderfull thing but don't change smart arse remarks after the fact and call them toungue in cheek, don't work.

 

And if characters like little leatherman here wanst to drag his irrelvance and crap into things then really that does highlight many things.

 

Anyway no point in correcting some of the comments as obviously who gives a rats bt at least some had the incentive to look and think for themselves.

 

Cheers, Kerry.

Edited by Kerry.
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