Quoted: GPS recievers are cheap and readily available 'consumer' electronics in the EU now… Garmin eTrex @ $140

Now, yes....how about in 1997?

But, now, it's all a moot point anyway, as handheld units here don't have the built-in skew anymore.

Which reminds me, I need to tell the person I gave my old GPS to, that it's for shit..

Quoted: How on earth are they going to prevent broadcasts (BROADCASTS..note this word) over a certain part of the world from a sattelite? What, are they going to line the USA with tinfoil and bounce the signal away? Can't be done. Someone else also posted the GPS sats use two signals... They send one signal, and one signal alone, for GPS usage. American GPS units, up until 2k, had a built-in fuction in them to deliberatly skew the clock on the handheld by up to several seconds each way of the actual time. This was why on old units your position would randomly jump anywhere from inches to meters different...if you're standing still and not moving at all. Used to drive me nuts on the GPS I had. You could easily defeat this..by going to Europe (or Canada, I believe) and buying a "foreign" GPS...problem was it was prohibitivily expensive. (Not that it wasn't expensive here to begin with, but units outside the USA cost a lot more, if you could find them) We're not talking brain surgery on dumbing down GPS's; it was all in the consumer handheld. The sats just sat above, broadcasting their time signals. The handhelds took the signal and skewed it. The only thing they can possibly do is shut down the whole system...but that'd wreak chaos globally. Imagine a supertanker who's relying on GPS locations to navigate the ship through some serious shoals..losing his GPS. Imagine far more serious events, happening all the time, and then just shutting GPS off....we can't quite do that, either.

I am not really sure what your saying about the GPS?  The Navistar satellites have always transmitted 2 signal (I actually think it is 3 now, with the addition of M band transmissions, but may be wrong).  The non-encrypted CA code and the encrypted P (Y) code. Other than military ones, GPS receivers only received the CA signal because there was no reason to get the P (Y) code because it was encrypted.  When SA was turned on, the accuracy would be within 100 meters, 95 percent of the time with the CA code alone.  The P (Y) or precision code allowed for accuracy with a  good Dilution of Position (satellite overhead position) to around 3 or so meters, although a good fix was normally around 7.5 meters without differential augmentation.  With SA turned off you get close too, but not up to P(Y) code accuracy, unless your willing to spend around 20,000 or more dollars for a survey set.  Survey sers used a few different algorithms and a form of positioning averaging in order to get submeter accuracy.

Differential augmentation like, WAAS etc solves for allot of the random noise that degrades accuracy.

SA or Selective Availability was the "built in skew" but it was built into the signal, not the receiver.  My old Mag 315 became allot more accurate once SA was turned off, it was normally within a few meters of the military AN/PSN-11 PLGR.  

However since the skew is in the signal, the government can turn that skew on at anytime.

Quoted: I am not really sure what your saying about the GPS?  The Navistar satellites have always transmitted 2 signal (I actually think it is 3 now, with the addition of M band transmissions, but may be wrong).  The non-encrypted CA code and the encrypted P (Y) code. Other than military ones, GPS receivers only received the CA signal because there was no reason to get the P (Y) code because it was encrypted.  When SA was turned on, the accuracy would be within 100 meters, 95 percent of the time with the CA code alone.  The P (Y) or precision code allowed for accuracy with a  good Dilution of Position (satellite overhead position) to around 3 or so meters, although a good fix was normally around 7.5 meters without differential augmentation.  With SA turned off you get close too, but not up to P(Y) code accuracy, unless your willing to spend around 20,000 or more dollars for a survey set.  Survey sers used a few different algorithms and a form of positioning averaging in order to get submeter accuracy. Differential augmentation like, WAAS etc solves for allot of the random noise that degrades accuracy.

I could have sworn I read years and years ago that the military GPS units and the civilan ones use the same GPS band/signal, and that the only differences between them was the handheld chipset (which would skew on the civvie units). Then again I read it on the internet so it must be true

Well, even if I did bite the bag on that part...there's still no way to stop transmissions over one small part of the globe

Quoted: Quoted: What will they ban next, sextons? You mean sextants?  Different thing entirely. 1911fan

Ban Sextons! Do it for the altar boys!

... Some of you forget, GPS was developed as a military requirement. Only after deciding to induce some error was it made available to civvies in peacetime. This doesn't surprise me one bit. I could damn near build my own cruise missile but I would have to rely of "off the shelf" guidance technology to steer it, and use Tannerite® for a warhead

Quoted: I could have sworn I read years and years ago that the military GPS units and the civilan ones use the same GPS band/signal, and that the only differences between them was the handheld chipset (which would skew on the civvie units). Then again I read it on the internet so it must be true Well, even if I did bite the bag on that part...there's still no way to stop transmissions over one small part of the globe

They do recieve the same CA signal, but with the SA turned on the civilian set was still only good to around 100 meters.  With SA turned off they are around 10 or so meters (some a little less, some allot more accurate if using WAAS).  SA can be turned on regions and off in others.

All you need:

This isnt anything new at all. There has always been a plan to instantly degrade or turn off regions.


Winston Time and money thats all.

Wanst there a thread about 6 months ago about a kid who had already made a small cruise missle? It was outside of the states but I cant recall ?

EDITED : found it

aardvark.co.nz/pjet/cruise.shtml

You Can Already Buy All The Bits Cruise missiles such as the Raytheon Tomahawk have proven themselves as an extremely cost-effective method of delivering a wide range of ordinance with pin-point accuracy against targets that may be up to 1,000 miles from the launch point. By using mil-spec GPS, highly sophisticated terrain recognition systems and a raft of other previously top-secret technologies, the cruise missile allows its owner to deliver a powerful offensive strike against an enemy with no risk to its own troops or vehicles. However, during the past decade, huge strides have been made in commercializing much of the technology on which the cruise missile is based and it is my firm belief that building a low-cost, autonomous, self-guided, air-breathing missile with a significant payload capability is now well within the reach of almost any person or small group of persons with the necessary knowledge and skills. Targeting/Guidance As mentioned above, one of the key components of a cruise missile's guidance system is a mil-spec satellite-based GPS system. Today, compact, high quality, high accuracy GPS receivers are readily available for just a few hundred dollars. The inclusion of an easily used computer interface in many of these units makes them well suited for use in a low-cost cruise missile (LCCM). While the GPS provides information necessary for tracking waypoints and identifying the final destination, smaller course corrections (for stability) can be provided by the solid-state gyro systems now readily available for use in model helicopters and aircraft. ..................................... More on site ....................................

Quoted: What will they ban next, sextons?

They're going to ban the nice guy that cleans my church?

Quoted: All you need: fwie.fw.vt.edu/vnhs/douthat%20state%20park%20topo%20map.JPG www.briski.us/Backpacking/gear/compass.jpg

Is that topo from Bath and Alleghany VA?

Quoted: Back when Pres Clinton turedn SA off, the FA school wrote a position paper than it was a bad idea because a terrorist was going to take an aircraft and turn it into a cheap cruise missle

Turning on SA wouldn't have made any difference on 9/11. Several hundred meters of uncertainty is still plenty to get the terrorists within visual range of the WTC or Pentagon. After that, it's just a matter of lining up the plane with the target.

Quoted: Quoted: What will they ban next, sextons? They're going to ban the nice guy that cleans my church?

No, no, no... The Mariner's new First basemen is the one who will be banned...

Quoted: You cannot turn off the non-encrypted signal and still use the encrypted, you can only degrade non encrypted.  The CA (Course and Acquisition) is required by P (Y) code receivers (Precision, encrypted).  In order for the P(Y) signal to be used the receiver has to first get the CA code, it than switches to the P(Y) code once it has its approximate location.

OK thanks.......Now I have to go and buy the GPS for dummies book!

What in the hell did you just say?

Essentially the satellites trasmit 2 signals L1 & L2.  L2 is the full-time encrypted signal with a higher-accuracy timing signal.  L1 is both an encrypted and unencrypted signal of lesser quality.  The latter is what civilian GPS uses.  Basically to be able to use the encrypted GPS, one has to acquire the L1 signal to get a ballpark area and then the L2 signal to get more precision.  

If, during a period of national emergency, the DoD turned on selective availability over the US, then the unencrypted L1 signal is skewed to the point of unusability or it is simply blanked out altogether.  That would leave the Encrypted L1 and Encrypted L2 (of higher accuracy) still being broadcast from the satellites.  This can be done system wide or in specific locations throughout the constellation.

Quoted: Turning on SA wouldn't have made any difference on 9/11. Several hundred meters of uncertainty is still plenty to get the terrorists within visual range of the WTC or Pentagon. After that, it's just a matter of lining up the plane with the target.

The fear was not the manned aircraft with GPS to get them close to the target; kamikazes proved that a human guided weapon even prior to GPS was more than adequate.  But the unmanned, GPS enhanced, auto pilot guided cruise missiles on the cheap.  

We wouldn't have to go to such measures if we simply KILLED ALL OF THEM!


Simple

Quoted: ... Winston Time and money thats all. Wanst there a thread about 6 months ago about a kid who had already made a small cruise missle? It was outside of the states but I cant recall ? EDITED : found it aardvark.co.nz/pjet/cruise.shtml

... Is that a job offer u-baddog?

Quoted: Quoted: I am not really sure what your saying about the GPS?  The Navistar satellites have always transmitted 2 signal (I actually think it is 3 now, with the addition of M band transmissions, but may be wrong).  The non-encrypted CA code and the encrypted P (Y) code. Other than military ones, GPS receivers only received the CA signal because there was no reason to get the P (Y) code because it was encrypted.  When SA was turned on, the accuracy would be within 100 meters, 95 percent of the time with the CA code alone.  The P (Y) or precision code allowed for accuracy with a  good Dilution of Position (satellite overhead position) to around 3 or so meters, although a good fix was normally around 7.5 meters without differential augmentation.  With SA turned off you get close too, but not up to P(Y) code accuracy, unless your willing to spend around 20,000 or more dollars for a survey set.  Survey sers used a few different algorithms and a form of positioning averaging in order to get submeter accuracy. Differential augmentation like, WAAS etc solves for allot of the random noise that degrades accuracy. I could have sworn I read years and years ago that the military GPS units and the civilan ones use the same GPS band/signal, and that the only differences between them was the handheld chipset (which would skew on the civvie units). Then again I read it on the internet so it must be true Well, even if I did bite the bag on that part...there's still no way to stop transmissions over one small part of the globe

STLRN is right.  You are wrong -- on all counts.  You can put away your BS flag now.

And selective availability had nothing to do with the chipset or the receiver (aka "user segment").  It is a pseudo-random error introduced into the transmissions of the various satellites.  It's controlled by the ground stations (aka "control segment").  It can be turned on or off and adjusted on short notice.  There is also some capability to apply selective availability only to certain parts of the globe.  The satellites (aka "space segment") are not geostationary.  They circle the globe in six separate orbits with at least four satellites in each orbit.  If the US wants to deny or degrade the civilian signal (C/A) in the Middle East, they simply make adjustments to the transmissions of whatever satellites are in view of that region for the duration of their observability.

By the way, errors in GPS positioning errors can be filtered by comparison to ground-based reference stations and/or by employing the signals broadcast by the FAA's WAAS (Wide Area Augmentation Service) satellites.  This is called differential GPS (DGPS) and has the potential for very high accuracy.  Other techniques can achieve millimeter accuracy.

In addition, Russia's GLOSNASS constellation works similarly to GPS, although without quite as much accuracy.  The GLOSNASS system is totally outside the US's control and can serve the same purpose as GPS for enemy targeting.  In fact, there are OEM boards out there that are very easy to use that integrate both GPS and GLOSNASS to achieve higher accuracy than either system alone.

The President can give the order to shut down GPS entirely if he wants, but a sufficiently sophisticated enemy could still easily and inexpensively direct ICBM's or missiles anywhere in the world they want.

CDMA cellphone networks rely on GPS timing signals for signal synchonization. What will happen to everyone with a Sprint or Verizon phone? The analog towers (where they still exist and for customers whose phones still support it) will not support that kind of load.

Maybe they'll ban 'em.  Anyone want a preban Garmin eTrex??

Interesting- I was already reading another thread here where several people on the West
coast confirmed GPS outtages at the same time this week.

As stated earlier- alot of our guys are carrying civilian units now, though there is a smaller
version of the PLGR that the military uses, I don't think they're in wide circulation yet.

Break out the compass, Sextant, maps and the good old Astrolabe!

Quoted: What will soccer moms use to find the closest mall in their GPS enabled mini-vans

I think the GM On-star system also uses the GPS system. I guess these people will have to look it up in a real map for a change to get from point A to point B.

If there is a terrorist organization out there that has the capability to build, support and launch a cruise missile with a 1,000 mile range believe me, the president has a hell of a lot more to worry about than whether or not to turn off the GPS constellation.

-Gator

Quoted: What will they ban next, sextons?

And instructors of the science of "dead reckoning" will be subject to mandatory licenceing.

Websites such as this will be shutdown.

Quoted: Quoted: Quoted: I'm sure the terrorists can't use a map and compass.  Terrorists know how to teach missiles to follow a map and compass with accuracy??? They are called smart bombs.

Which use GPS.

Quoted: CDMA cellphone networks rely on GPS timing signals for signal synchonization. What will happen to everyone with a Sprint or Verizon phone? The analog towers (where they still exist and for customers whose phones still support it) will not support that kind of load.

They use rubidium clocks as a backup timebase...no worries...

Quoted: If there is a terrorist organization out there that has the capability to build, support and launch a cruise missile with a 1,000 mile range believe me, the president has a hell of a lot more to worry about than whether or not to turn off the GPS constellation. -Gator

+1

Quoted: CDMA cellphone networks rely on GPS timing signals for signal synchonization. What will happen to everyone with a Sprint or Verizon phone? The analog towers (where they still exist and for customers whose phones still support it) will not support that kind of load.

The cell sites would free run for awhile.  Then they would time off the MTX (the main switch) after a certain threshold is met.

Quoted: Hmmm...will this just disable the WAAS features...or the whole shebang? Might be time to unload GRMN

Sweet. Time to look for a Buy opportunity when the herd stampedes away from GRMN in fear.

well, back to:

www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&productId=145677&catalogId=10001&classNum=267&subdeptNum=137&storeNum=14