News

5.9k · October 15, 2002

News

If your house catches afire, and there aint no water around,

Throw your jelly out the window; let the dog-gone shack burn down.

**Huddie Ledbetter**

October 15, 2002

So

I just need a fix!

October 15, 2002

So, am I the only one that can't open that link?

It's a MIL site, so maybe we regular humans don't have access?

Thanks,

Tim

KB5OGH

=============================

I just need a fix!

5.9k · October 15, 2002

Oh crap, forgot about that, sorry. Here's the whole thing pasted in:

U.S. News & World Report

October 21, 2002

Keeping Our Bearings

The coming war over the global positioning system

By David Whitman

The war against the Taliban made heroes of soldiers and pilots–and of 24 small satellites, broadcasting feeble navigation signals from thousands of miles up. The global positioning system, or GPS, guided bombs to their targets with stunning accuracy and helped ground forces get their bearings and call in airstrikes in unfamiliar terrain. Now planners for a possible war in Iraq anticipate that Saddam Hussein's forces will try to neutralize that advantage by jamming the GPS signals, potentially sending bombs astray and disorienting soldiers.

A 2001 report from a commission chaired by Donald Rumsfeld before he became defense secretary concluded that the Iraqi military has jamming technology, and foreign news accounts suggest that Baghdad has already tried to jam air patrols in Iraq's no-fly zones. Last month the Wall Street Journal reported that a $39.99 jammer available on the Internet might be enough to make U.S. precision-guided bombs and missiles miss their targets. Military analyst James Zumwalt has even predicted GPS jammers could soon "have the same impact as did the stone used by David to slay Goliath."

Most military experts, however, think that GPS jamming may prove less deadly in practice than David's slingshot. Thanks in part to existing antijam features, new technology, and some simple tactical maneuvers, the military may be able to protect its alleged Achilles heel. Even successful jamming wouldn't necessarily hobble U.S. forces, say officials. "You can't buy a $40 jammer and send a JDAM [a GPS-aided bomb] awry,'' says Col. Douglas Loverro, the Air Force's Navstar GPS systems program director in El Segundo, Calif. "Just because the GPS is jammed, the bomb still falls–all we are arguing about is how close [it hits]."

Swamped. GPS, perhaps the biggest advance in navigation since the compass, is easy to jam because the signals from the distant satellites are so weak–akin, say, to a 25-watt bulb from 11,000 miles away. A more powerful local source easily swamps them. Mario Casabona of Electro-Radiation Inc. in Fairfield, N.J., a company that builds low-cost antijamming devices, says his "rule of thumb is that if a country has a RadioShack, it will have a jammer. You can build a jammer for about $500." A low-power 4-watt jammer built by the Russian firm Aviaconversia can, with a clear line of sight, block a receiver from picking up GPS signals for up to 124 miles away. The U.S. military, meanwhile, has become far more dependent on GPS since the Gulf War in 1991, when troops used GPS receivers to navigate the trackless Iraqi desert. Today, the armed services have more than 500,000 GPS receivers, most of them on precision-guided missiles, bombs, and other munitions.

Many GPS-equipped weapons have some built-in protection. GPS satellites broadcast on both a military frequency and a commercial frequency used by civilians. And while military GPS receivers usually use the civil code to acquire the military "P" frequency, it is much harder to jam a military receiver once it has locked into P code, because that signal is more robust. "It is probably 1,000 times harder to knock you off signal than to block you from acquiring GPS," says Colonel Loverro, which means that a jammer that can block GPS acquisition for 100 miles can jam the military signal for a few miles at most. Typically, planes carrying JDAMs lock on to the military frequency well outside of jamming range.

Even if the Iraqis did succeed in jamming the military signal, the JDAM has a backup inertial navigation system that doesn't rely on GPS. Guided by inertial navigation alone, a JDAM's accuracy decreases from an average of about 40 feet to about 100 feet. In Baghdad, 60 feet might make a tragic difference between bombing a school and blowing up a military installation. But for targets that require a surgical strike, other precision weapons that don't depend on GPS, such as laser-guided bombs, could be used.

Null and void. Besides these backup technologies, the military has ways to actively thwart jammers. One might be to track the source of the jamming signal and destroy it. Another is a technology added to many planes since the Gulf War: "nulling" antenna arrays. The antenna arrays can block reception of signals from the direction of the jammer, allowing the receiver to "hear" GPS signals from other directions.

Lockheed Martin and Rockwell Collins have developed an even more powerful countermeasure called G-STAR, which will be installed in one missile type starting next year. The G-STAR, which sounds like something fresh out of Star Wars, partly or fully blocks the signal from a jammer and then redirects the GPS receiver through "beam steering" to look for other nonjammed satellites. In the coming decade, the military will also field a new generation of more powerful GPS satellites, which will reduce the jamming threat.

For now, GPS jamming may hamper ground troops more than pilots. Soldiers lugging hand-held GPS receivers or maneuvering GPS-guided artillery and tanks won't have the luxury of locking on to the military signal before they come into jamming range. In most cases, though, a jammed GPS receiver simply won't work, alerting the troops not to trust it. Soldiers are also trained to practice crude versions of high-tech antijamming measures. They can crawl behind a jeep or humvee, using its body to partly block the signal coming from a jammer on the other side. Or they can stick their GPS receiver in a coffee can so they can "beam steer" toward satellites away from the jammer.

As Colonel Loverro points out, "ground troops did maneuvers for years without GPS," relying on visual clues, scouts, photographs, maps, and military intelligence. With no foolproof means to prevent jamming, either on the battlefield or in the sky, troops may sometimes have to improvise.

If your house catches afire, and there aint no water around,

Throw your jelly out the window; let the dog-gone shack burn down.

**Huddie Ledbetter**

October 15, 2002

Thanks for the post!

What with all the dependency that many weapons have on GPS it's nice to know that the affect of jamming is counterable....

Tim

KB5OGH

====================

I just need a fix!

October 15, 2002

This is quite the news service you have! The article is dated October 21st... it's the 15th today! DOes it have lottery numbers from next week as well?

Ian

Mobile Cache Command

1k · October 15, 2002

quote:
...the military has ways to actively thwart jammers. One might be to track the source of the jamming signal and destroy it...

What do they mean "might"? Like SAM sites, these or any other sites emitting hostile radio signals will surely be on the short list of first targets.

Worldtraveler

October 15, 2002

quote:
Originally posted by servman:
This is quite the news service you have! The article is dated October 21st... it's the 15th today! DOes it have lottery numbers from next week as well?

Ian

Mobile Cache Command

LOL! Good catch!

1.4k · October 15, 2002

Being retired military, I have some good idea of just what might happen, on both sides.

HOWEVER......

I am not sure that us civilians need worry. If that Wacky Iraqi does jam the GPS system, he will more likely target the mil freqs, and will he have enough left to do the civ freqs too? Dunno the answer for sure, but I doubt it.

Mike. KD9KC.

El Paso, Texas.

Citizens of this land may own guns. Not to threaten their neighbors, but to ensure themselves of liberty and freedom.

They are not assault weapons anymore... they are HOMELAND DEFENSE WEAPONS!

1.6k · October 15, 2002

Good article! Thanks for posting it.

KD9KC, we won't have to worry about any jamming here in the U.S. Jammers are local.

Terrorist here might try to use jammers, but for what purpose? We have signs on every corner.

CR

October 16, 2002

Can we focus on the important thing here- Could they make it even more difficult to find the elusive cache?

October 16, 2002

I have no doubt that our very capable military can overcome any countermeasures that come into play...the real issue is if we can jam our commander-in-chief from doing anything stoopid.

It sure would be cool to put together an inexpensive *VERY* localized jamming device (solar powered?) that could be deployed near a cache site...that would be pretty funny. Under the encrypted clues, you could say "deploy radio-seeking missile before getting close to the cache site".

October 16, 2002

i like your idea infosponge but i think it would be a violation of fcc regulations.

on another note, the way i read the article the jammimg devices have a limited range so if sadaam did jam signals in our part of the world wouldnt we have more to worry about than caching?

another thing, the article refered to two signals bases, civilan and defense, are these signal independent and what signals do airlines, engineers and the like use? can civilans possibly access the 'defense' signals?

October 16, 2002

Jamming!!!! That's it!

Whenever I turn on the cruise control in my car and duct tape my GPSr to the steering wheel, it always ends up in the ditch. It must be the jamming.

V7L

October 16, 2002

I don't think the FCC cares about things below a certain power level...I could be wrong. I sure wouldn't bring one onto an airplane or anything, but out in the woods miles from any potential harm to infrastructure, it would be funny to have a cache in "cloaking mode". :-)

I remember making a spark-gap generator to disrupt TV signals in my house to annoy a relative, and that ran off a single AA battery.

October 16, 2002

The military signal is available to authorized users, but it is encrypted and therefore useless even if you could recieve it.

quote:
another thing, the article refered to two signals bases, civilan and defense, are these signal independent and what signals do airlines, engineers and the like use? can civilans possibly access the 'defense' signals?

October 16, 2002

The FCC doesn't notice signals weaker than a given whatever, but if you were to make a jammer, you would indeed be running afoul of the regs. There's a company that's been trying to get FCC approval for a cell phone jammer for theaters and such, and the FCC's basically been telling them that any intentional jamming is illegal. (It's that old "can't cause interference; must accept interference" or whatever thing from those fine print sheets with all the electronics.)

October 16, 2002

I guess that makes sense ClayJar...as annoying as cell phones in theaters are, I can imagine there's a safety concern with jamming them altogether. And something that can jam a cell phone probably does nifty things to pacemakers too.

I'm guessing my chances of being hauled in by the FCC for putting a GPS jammer with a 60-foot radius out in the middle of the forest is going to be next to nil, though.

October 16, 2002

quote:
In most cases, though, a jammed GPS receiver simply won't work, alerting the troops not to trust it.

Just how far do you trust the military?

------

O God, I could be bounded in a nutshell, and count myself a king of infinite space, were it not that I have bad dreams.

Hamlet, II.2 252-253

October 16, 2002

It's my understanding that sportsbooks in casinos actually have working cellphone jammers. They're allowed because it's illegal to use any sort of two way communications device whilst in a sportsbook.

Perhaps it's just the interferance from all of the video and audio equipment. Perhaps it's like that "don't pee in the water" chemical.

I'll ask the Mirage's Hotel Sound and Video guru the next time I see him. Since he's also a ham, he'd know how such a devise could get FCC approval.

October 16, 2002

Just out of curiosity . . .

The orginal link in this thread was to a .mil url. Did that page have a copyrighted US News & World Report article on it? If so, how does the government justify that?

Fro.

________________________________________

Geocaching . . . hiking with a purpose

October 16, 2002

quote:
Originally posted by CreagerStone Family:
It's my understanding that sportsbooks in casinos actually have working cellphone jammers. They're allowed because it's illegal to use _any_ sort of two way communications device whilst in a sportsbook.

Perhaps it's just the interferance from all of the video and audio equipment. Perhaps it's like that "don't pee in the water" chemical.

I'll ask the Mirage's Hotel Sound and Video guru the next time I see him. Since he's also a ham, he'd know how such a devise could get FCC approval.

Even with all of the lobbyists that the gaming industry can afford, jammers still aren't legal, even in a sportsbook. Most of the time that a cell or such doesn't work in such a place it is from all of the other electronics in the area, and that you're in a dense, large building.

I have used a cellphone from just outside a sports book, but the signal wasn't all that great. Also, I am on call a large portion of the time, and I monitor my pager in such areas to make sure that I am getting a signal. Any jamming device in such an area would probably also knock out my pager, which it hasn't yet.

Now, this isn't to say that some casinos aren't using "illegal" equipment. After all, they could afford the fine if the unlikely event that they get caught.

VegasCacheHounds

1k · October 16, 2002

I read recently of some new construction material (wall & ceiling tiles, I think) being marketed to theaters that will shield the enclosure against cell phone signals. Accomplishes the intent without the legal hassles of jamming.

Worldtraveler

October 16, 2002

Wow...I guess it doesn't take much of a signal to jam a (consumer-grade) GPS receiver. Taking this web site at it's word, it claims a 0.01 watt jammer could be effective at a 10 km range, and a 10 watt jammer could be effective at a 320 km range!

Jamming Vulnerability Table

I found a (US military) web site that actually shows the theory behind how to construct a jamming device, but I won't post that one...you can google it out yourself if you're interested.

I'm assuming that cruise missiles use a combination of GPS and inertial navigation, so how effective something like this could be against a hardened weapon is up for debate.

October 16, 2002

would it be sporting to put one of these in a cache?

>Personally Responsible for the Recovery of .00244% of the Benchmark Database!<--watch this number!

1k · October 17, 2002

quote:
Originally posted by Raouljan:
would it be sporting to put one of these in a cache?

Save your money and find a hiding place with heavy tree cover or other obstacles to block/bounce the signals. Very low-tech, but the result is the same.

Worldtraveler

January 18, 2003

For those who don't read slashdot...

GPS Jamming Article

Mentions a build it at home jammer...

1.6k · January 18, 2003

I read that article about building your own jammer. It'd be easy if you were a very experienced builder.

But what caught my eye is the author mentioned you could build one and then practice your anti-jamming techniques. You really only need a shield to defeat the jammer because of the frequncies it uses. The very mechanics that causes problems with the signal can be used to defeat the jammers. It could be as simple as hunkering down on the lee side of your APC. Airborne GPS could use shields to block signals from the ground--and you know the Iraqi will not have anything in the air.

Not only that, but the Wild Weasels will have something to say about any jammers.

Nah, I don't think we have anything to worry about in regards to jammers.

CR

1.6k · January 18, 2003

i want to buy a jammer for the next TEAM KFWB GPS cache

zuuk

January 18, 2003

I would like to remind everyone in this thread, that geocachers are not the only users of the GPS system in the United States, or anywhere for that matter. In fact Geocachers are only playing a very cheap game with with a multi-billion dollar satellite system, designed by our government. Aside from the obvious uses by the military, There are any number of other mission critical uses of the GPS system, which are being used everyday by other civilian and public entities. Some mission critical examples include:

Many aircraft, including Airliners and private airplane are coming to relie on GPS system for primary navigation. Imagine what would happen if a geocacher placed a jammer near a cache on some mountian top,trying to foil other geocachers, and jammed the GPS reciever on a airliner while it was making an instrument approach to an airport 20 or 30 miles away. Remember that the GPS system was designed as a navigation system, and it is a felony federal offense to knowingly and willfully disrupt or obstruct or interfere with the navigation of aircraft or vessels at sea.

I believe that in this type of situation, the goverment would track town and destroy any such jamming device as rapidly and swiftly as any one that Saddam Hussien might deploy.

In addition to the above scenario, consider that 911 centers track the location of police and emergency vehicles with GPS systems, and will be tracking the location of 911 cellphone calls in the near future.

And surveyors, On-Star vehicle locating systems, search and rescue teams, etc...

I think we ought consider the consequences of what we ponder in fun?

January 18, 2003

quote:
Imagine what would happen if a geocacher ... jammed the GPS reciever on a airliner while it was making an instrument approach to an airport 20 or 30 miles away

The airliner would merely revert to another navigation system. There's no need to exagerate the seriousness of any system vulnerability. No life critical system is ever designed with the kind of brittlenes you imply. Currently all GPS approaches are nothing more than overlays onto older non-precision approaches, all of which are still in operation.

Besides, the jammer described in the article has the capability of disrupting the operation of a consumer grade GPSr at a range of a few hundred feet under ideal conditions, no more.

January 18, 2003

"In the coming decade, the military will also field a new generation of more powerful GPS satellites, which will reduce the jamming threat"

Does this mean that my eTrex will be able to work under tree cover?

I'm hopng that the cavers don't get a hod of these jammers

Mickey

Max Entropy

More than just a name, a lifestyle.

January 18, 2003

This month's SA has an article about GPS guided weapons.

Personally, as an EE, I don't think there's much the military has to worry about. It can be as simple as ignoring signals from the ground or horizion.

Or just targeting the source of the interference...no big deal.

George

January 18, 2003

quote:
Originally posted by kevman42:
For those who don't read slashdot...

http://computerworld.com/securitytopics/security/story/0,10801,77702,00.html

Mentions a build it at home jammer...

And here's the actual article of how to do it.

January 21, 2003

quote:
Originally posted by canadazuuk:
i want to buy a jammer for the next TEAM KFWB GPS cache

zuuk

Or one could just give coordinates that are close but not exact. Leave out the thousandths value (48.34X), for example...

Ron/yumitori

January 22, 2003

This article from GPS World is interesting for those of us who use the civilian signals. http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=43404

1.4k · January 23, 2003

Long before I retired, we had something on our missiles called TOJ, or Track On Jam. Isn't it nice that the target can provide a beacon for the misslie to home in on? Since I have been out nearly 8 years now (since I couldn't stomach serving under Klinton any longer) I am out of touch with the latest stuff. But one thing I am certain of... it has only gotten better. And being a ham since I was 8 years old, I know it is only local at that freq. So most of us are not likely to see it. Cache on!!!

Mike. Desert_Warrior (aka KD9KC).

El Paso, Texas.

Citizens of this land may own guns. Not to threaten their neighbors, but to ensure themselves of liberty and freedom.

They are not assault weapons anymore... they are HOMELAND DEFENSE WEAPONS!

January 23, 2003

I understand that they now have a non-nuclear EMP cruise missile now.

So, the first order in battle will be to send in the EMP before the GPS-guided JDAM munitions arrive to take out the jammers, radar, computers, Game Boys and radios.

Mickey

Max Entropy

More than just a name, a lifestyle.

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