User Panel
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.. |
|
|
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. |
|
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 |
|
|
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
|
|
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. |
|
|
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
|
|
|
They're going to ban the nice guy that cleans my church? |
|
|
Is that topo from Bath and Alleghany VA? |
|
|
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. |
|
|
No, no, no... The Mariner's new First basemen is the one who will be banned... |
||
|
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. |
|
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 |
|
... Is that a job offer u-baddog? |
|
|
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.
|
|
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!
|
|
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 |
|
And instructors of the science of "dead reckoning" will be subject to mandatory licenceing. Websites such as this will be shutdown. |
|
|
Which use GPS. |
|||
|
They use rubidium clocks as a backup timebase...no worries... |
|
|
+1 |
|
|
The cell sites would free run for awhile. Then they would time off the MTX (the main switch) after a certain threshold is met. |
|
|
|
|
|
|
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.