Local Police Want Right to Jam Wireless Signals

Local Police Want Right to Jam Wireless Signals

By Spencer S. Hsu Washington Post Staff Writer Sunday, February 1, 2009; A02

As President Obama's motorcade rolled down Pennsylvania Avenue on Inauguration Day, federal authorities deployed a closely held law enforcement tool: equipment that can jam cellphones and other wireless devices to foil remote-controlled bombs, sources said.

It is an increasingly common technology, with federal agencies expanding its use as state and local agencies are pushing for permission to do the same. Police and others say it could stop terrorists from coordinating during an attack, prevent suspects from erasing evidence on wireless devices, simplify arrests and keep inmates from using contraband phones.

But jamming remains strictly illegal for state and local agencies. Federal officials barely acknowledge that they use it inside the United States, and the few federal agencies that can jam signals usually must seek a legal waiver first.


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And of course there are a mutlitude of other frequencies which you can use to set off a bomb. For example a tone sent over a FRS/GMRS radio.. Put a directional antenna on the recieving device and have the transmitter in the directional antennas path. There's next to no way of jamming that.


Reply to
Tony Toews [MVP]

Not to mention the CB band, Amateur radio bands, et al. Hell, you could even use a 49MHz baby monitor for the purposes at hand.

And not for anything but aren't the miraculous trunked radio systems up in the 800MHz band? And isn't some cell service right around that same band?

Should be interesting as this flies afoul of FCC regulation.

***** Moderator's Note *****

I assume that the Secret Service has considered all the possibilities, but it's true that there are a lot of things other than cell phones which pose a risk.

Bomb makers are not usually expert technicians. Hollywood stereotypes to the contrary, the typical bomber is, above all, a creature of habit: he knows one design and sticks to it. If a bomber learned a design that uses a cell phone, he'll stay with it.

There's another factor, which is that cell phones are not, in and of themselves, suspicious. It may be convenient to use a cell phone as part of a triggering mechanism, but that's not what makes cell phones per se attractive to bombers. A bomber's biggest concern is how to blend into the crowd after planting a bomb: a cell phone in a bomber's pocket is just a cell phone until he dials the fatal number, but any other kind of transmitter would single him out.

If I had to guess at which frequencies the Secret Service would be most likely to jam, other than the cellular channels, it would be the ones used for remote control of model aircraft and other toys. Not only are the transmitters and receiver easy to obtain, small, and designed to work on low power - they're also designed to operate remote actuators, e.g., the electromechanical linkages between an r/c receiver and a model aircraft's control surfaces. That capability is, of course, tailor made for use in triggering a bomb.

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I think this is another case of someone in government making a decision without understand anything about the technology being used. When I went through training dealing with potential bombs one of the most important rules was to turn off all transmitting devices including cell phones, two-way radios, two-ways pagers, wifi devices, etc. The RF could potentially set off the bomb. I can't even fathom wanting to come in with a jammer.

I think "T", "hancock4", and Bill all have valid points. On one hand you would have to block off the entire spectrum because any RF device could be used as a trigger. While cell phones have moved away from the 800 MHz band, pagers haven't. And VHF pagers are still used and there are law enforcement agencies still on VHF.

But I understand Bill's point too. Bombers aren't all mad geniuses. They're going to use what worked before and a cell phone is less conspicuous than, say, a scanner or two-way radio. So perhaps jamming the cell phone band would nullify 99% of the bombs out there, assuming the jammer itself doesn't set the bomb off. While it's true someone could design a bomb that responded to a code and not the RF energy itself, I am reminded of a friend who set his GSM phone on his paper shredder and when the network polled his phone it turned on the shredder.

I'm also of the mindset that 9/11 was a fluke and we're jumping at our own shadows. Jamming cell phones isn't going to help public safety, all it'll do is let the cat out of the bag cell phone use will become the next smoking/non-smoking battle, more than it already is.


Reply to
John Mayson

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