Can GPS signals be scrambled?

[wkwalrond]

Here is my short story.... I rarely use the internal antenna but on a recent trip to Washington D.C. and Atlanta GA I used it extensively. It was great to find places to eat! I know that two more people are going to become iQue owners after they saw mine in action (your welcome Garmin).
Now I am in Iraq and it won't pick up any satellites. Basically, as soon as I got off the plane in Kuwait it would not work. I figured I would try it out once I arrived in my final destination in Iraq and it is still a no go.
My question is this- Can the US Gov't scramble GPS signals to prevent the recreational user from acquiring satellites on their GPS? I'm not involved with the military so I don't know if this is a possible reason for my iQue not to work.

Thanks!

[JMckie]

First eliminate the most obvious answer. Does the external antenna work?

[rwsmith123]

Probably.

Also since you traveled a large distance since your last gps acquistion it can take longer to lock on. You can help it out by setting your location manually. Also be sure to adjust the timezone.

[wkwalrond]

I didn't bring the external antenna. It's hardwired in my car back in the UK. :(

[wkwalrond]

Originally posted by rwsmith123
Probably.

Also since you traveled a large distance since your last gps acquistion it can take longer to lock on. You can help it out by setting your location manually. Also be sure to adjust the timezone.

I guess I should have been more specific with what I have done so far.... I did set my location manually and I waited up to five minutes for the iQue to acquire. Maybe I should try again and wait longer.

I wonder if my antenna decided to crap out? At least it is under warranty until November.

[jonasolof]

What about the time setting? The iQue won't work if time is way off.

[kokopeli123]

Originally posted by wkwalrond
My question is this- Can the US Gov't scramble GPS signals to prevent the recreational user from acquiring satellites on their GPS? I'm not involved with the military so I don't know if this is a possible reason for my iQue not to work.

Thanks!

1) The GPS satellites can be set to degrade the accuracy of GPS signals (it's called selective availability but would effect the entire world - see http://geography.about.com/library/weekly/aa050400a.htm);
2) GPS jammers are available on the open market and can effect the satellite signals (since they can also effect military GPS receivers they are usually destroyed as quickly as possible - see http://www.computerworld.com/securitytopics/security/story/0,10801,77702,00.html);
3) There is a standing US Presidental directive that the US will not degrade the signals from GPS satellites (too many commercial industries depend on the GPS timing signal to synch their hardware/software and for navigation - see http://www.igeb.gov/sa/benefits.shtml).

Having written all that, I concur with rwsmith123's assessment. Last time I went to Kuwait it took about 30-minutes to get the updated almanac and get a position plot.

If time doesn't solve your problem then you're most likely looking at a failed internal antenna RMA.

kokopeli123

[wkwalrond]

Originally posted by jonasolof
What about the time setting? The iQue won't work if time is way off.

I had the time zone set to Moscow +3.00 hrs, but I went ahead and changed it it Saudi Arabia +3.00 hrs. No difference after trying to acquired for about 15 minutes. No hollow bars, nothing. One interesting thing was that on the "acquiring satellites" screen, the satellites were moving all over the place. One second a satellite would be in the SW then the same satellite would be in the NE. I can only guess that the iQue is trying to determine what region of the world I am in and trying to find the satellites in different positions of the sky.

I have a feeling that I lost my internal antenna....

[jdcrowley]

I have read that the military has the capacity to (and in Iraq surely would) degrade a GPS signal locally.

Until a few years ago this was done worldwide so that terrorists and military adversaries wouldn't be able to use GPS. During this time the military alone retained the ability to descramble the signal and get accurate readings. The development of the ability to scramble the signal in select areas was probably more important in leading the military to stop scrambling the worldwide signal than was pressure from businesses.

[jonasolof]

On the other hand there is mapping software available for Iraq made by US companies recently. Nothing said about need for military grade receivers. It is marketed to journalists, contractors, NGOs etc.

[zos]

I don't know if this will work, but I had a similar problem earlier this month. I was all set to RMA my iQue until later along on my trip I tried to acquire again. This time I went to set my new location, but instead of choosing by the map, I hit the "Automatic" button. Within seconds I was beginning to acquire satellites again, and I have not had any trouble since. Actually, I've hit that automatic button again several times and it actually seems to speed up acquisition for me. Call me crazy, but I stand by this information.

[kokopeli123]

Originally posted by jdcrowley
I have read that the military has the capacity to (and in Iraq surely would) degrade a GPS signal locally.

Here's an excerpt discussing localized SA:

I heard that SA will be left on in certain parts of the world. Is it still on in my country?
No. You have been misinformed. Selective Availability was a global degradation of the GPS service. It could not be applied on a regional basis. By turning it off, the President immediately improved GPS accuracy for the entire world. The United States has no intention of reactivating SA ever again.

In times of military conflict or crisis, the U.S. Department of Defense has demonstrated the capability to deny non-NATO access to GPS in a localized theater of operations without affecting anyone outside that area. This is accomplished through means other than SA.

Users in the U.S. and the rest of the world should now be experiencing the same basic GPS accuracy of 10-20 meters or better.

kokopeli123

[ragman]

Selective Availability was not a matter of gaining or denying access but a degradation of accuracy by dickering with the clock among other things. You still received the signal from the satellites but the info was wrong enough to give errors of +/- 100 meters. When Dubya's daddy sent our boys over there, not enough military GPS units were available so they bought civilian units and turned SA off. Us old fart civilians enjoyed the benefits. SA became less useful as differential GPS become more common. When Clinton issued the Executive Order to turn off SA you can rest assured that the military (it IS their system) was comfortable with that decision because they had the ability to control things when and where they needed to.

All that being said, I doubt the US military is giving or allowing to be purchased military units. Civilian contractors and NGO's need to find there way to and fro. So, the first thought is your iQue.

Ragman

PS. A forum search on the keyword Iraq will return posts that will lead you to think it is your unit.

[Tinker]

It may be relevant:-

There has been a topic"GPS and military bases" on the forum at
globalpositiongsystems.co.uk recently.

I have not had chance to travel near a base, and I felt it was mostly "hot air". Will check it if/when I go near to a couple of major radar sites.

Comments please.

[II00I00I]

Apparently your GPS goes 'tilt' when passing by the Russian embassy in Brussels. It looks like they are using a GPS scrambler. Can anyone confirm/test this?

[jonasolof]

Originally posted by II00I00I
Apparently your GPS goes 'tilt' when passing by the Russian embassy in Brussels. It looks like they are using a GPS scrambler. Can anyone confirm/test this?

No. The belgian foreign office wouldn't let them. The use of transmittors on embassies is probably regulated in diplomatic protocol.

[II00I00I]

Perhaps the foreign office should test it again, because someone let me know they experience this on 2 different occasions.

[jonasolof]

Here:

Ambassade de Russie en Belgique
66, avenue de Fre - 1180 Bruxelles
Tél.: (02) 375.91.21, 374.35.69


I could test next time I go for the wine tasting club meeting which is just nearby. Last sunday my wife drove home and I looked at the iQue. But I didn't wait for a satellite fix before we took off, so there is no track until further down the street.

Then, if there is a disturbance I could just nock on the door and ask them to please shut it down, because I need my GPS to find my way home after the wine tasting.... Sounds like a good reason for enquirey, doesn't it? Nazdarovye!(skål)

[coop]

3) There is a standing US Presidental directive that the US will not degrade the signals from GPS satellites (too many commercial industries depend on the GPS timing signal to synch their hardware/software and for navigation - see http://www.igeb.gov/sa/benefits.shtml).

Oh yes, and a Presidential directive has never been ignored in a time (or location) of conflict?

Ha.

If you're in a sensitive location, I'm sure that the military has very good reasons, and the ability to mess with the signals in a local area. This would even enable them to "sort of" comply with the directive.

coop

[cancellier]

Originally posted by coop
If you're in a sensitive location, I'm sure that the military has very good reasons, and the ability to mess with the signals in a local area. This would even enable them to "sort of" comply with the directive.

coop

OK Folks, let's think about this. Why would the military scramble signals in an area of military operations? They are dependent on GPS for everything from radio synchronization to weapon guidance. You have heard of the handy dandy Joint Direct Attack Munition (JDAM)? It needs GPS for an accuracy update after it comes off the aircraft. If you degrade GPS over the area you are using one, you degrade the accuracy of the bomb.

Take a look at this article to see what they are REALLY doing...

http://www.peterson.af.mil/hqafspc/News/News_asp/nws_tmp.asp?storyid=04-043

Have a good one,

Mike

[coop]

From the referenced article:

“As navigation analysts, we do a lot of thinking outside the box to refine GPS support to the warfighter while minimizing harm to global (civil) users ,” said Captain Mendicki. “We continually probe the edges of the envelope to find the next level of improvement. At the same time, we provide 24-7 support to the on-duty payload officer for any on-orbit or system level problems. The world relies on GPS. It’s a highly complex system that takes time and dedication to understand. Working with such a highly dynamic system makes the job both challenging and rewarding.”

(Italics mine.)

Exactly.

They can and do whatever they need to do to get the job done. I have no doubt that that could mess with the signals in a local area if they needed that for a particular reason. They would be able to define the size of that area (local jamming, whatever) as required. Could be long term, would probably be short term, based on operational requirements. And they're not gonna worry if someone can't get a fix on their commercial grade GPS while in a war zone! There are more inportant fish to fry!

coop

[cancellier]

Originally posted by coop
They can and do whatever they need to do to get the job done. I have no doubt that that could mess with the signals in a local area if they needed that for a particular reason. They would be able to define the size of that area (local jamming, whatever) as required. Could be long term, would probably be short term, based on operational requirements. And they're not gonna worry if someone can't get a fix on their commercial grade GPS while in a war zone! There are more inportant fish to fry!

coop

Actually the C/A code (Coarse Acquisition code or 'commercial' version) user is just as important. Remember the big flap about the military having trouble getting equipment over to the war? Well one of the problems was in getting enough military GPS receivers over there for soldiers on the ground to use. So, many went out and bought their own. Of course you can't go out and buy a military-grade GPS at your local outdoor store. Most of them bought the same stuff we have and used them for navigating around Iraq. So, the GPS flyers need to be very careful how they affect the signal.

Taken from an Army guy's Lessons Learned in Iraq page:

Commercial GPS: As is widely known, many soldiers purchase their own GPS systems rather than use the PLGR. The Rhino was provided to the 82d <Airborne Division> as part of the rapid fielding initiative. Overall, soldiers were very appreciative of this addition to their MTOE. The Rhino was a vast improvement over the PLGR because of the weight, volume, power consumption and performance – the Rhino consistently acquired satellites faster than the PLGR. However, the soldiers stated they did not use the communications capabilities of the Rhino, at least not extensively, because it was not secure and consumed batteries too quickly in this mode.

http://www.rkba.org/guns/lessons_iraqi_freedom.htm

Now if you want to jam signals in a localized area, try this:

http://www.acig.org/phpBB/viewtopic.php?topic=2379&forum=5&1

I've played with these things. They are pretty neat. Dr. Antonov has quite a little racket going on there...

Mike