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U.S. Government Sometimes Jams Keyless Car Locks?
PizzaFace writes "The Washington Post reports that in certain towns (generally near military bases), on certain days (such as the day an aircraft carrier returns to port), keyless car entry systems and remote garage door openers mysteriously fail. While some frustrated motorists blame aliens, the FCC says the jammed frequencies belong to the U.S. military. The good ol' Post even tracks down a government contractor who all-but-confirms the source of the interference."
This is one of the reasons medical devices have to go through some rigorous testing and use approved frequencies. Even so, mistakes do occur.
When a pacemaker fails, it tends to get noticed. Early pacemakers had trouble with improperly shielded microwave ovens - mostly because the pacemaker itself was improperly shielded. Pacemakers that used a magnetic sensor for the on/off function ran into trouble if a strong magnet was waved over the patient's chest. Some of the early AV sequential pacemakers with the ability to change heart rate based on activity sensors would, if incorrectly programmed, suddenly throw the patient into an artificial 2nd degree heart block when the patient's heart rate exceeded a specific amount.
Urban legends contribute to percieved problems. Notice all the hospitals with "No Cell Phone" signs. Then notice all the cell phones in use by the doctors and the EMS personnel walking around with Handi-Talkies. Oops....
This sig seemed like a good idea at the time....
You don't need to delve into urban legend. Back in 1998, a dozen wireless heart monitors went offline at a major Dallas-area hospital when WFAA-TV turned on its HDTV transmitter for the first time.
I write in my journal
The interference is in the Military A-Band, which covers 233-403 Mhz. This is used for shipboard radars, as well as radar at airfields. You don't have to use Ghz frequencies for radar, in fact the first WWII radars used were around 100 Mhz, IIRC.
My buddy has the exciter from a shipboard radar as his "Ham Radio" rig. This item generates 1000W CW and about 100 KW in pulse mode, which is what the radars use. It has 4 sections that each handle 1/4 of the band from 10 Khz to 1 GHz. That was then fed to a 10KW Power Amplifier and out. Just the exciter part sits in 3, 6-foot rack cabinets!
The average pulse power in the radars is around 100,000 Watts, and can be pumped up several orders of magnitude to "burn through" jamming if necessary (peak pulse power levels around 1 GWatt!) That field is being constantly swept around the area looking for threats using phased array panels, much faster than the old "Battlezone" radars, so the RF field is effectively everywhere.
Key fobs, RF remotes and Garage door openers are using the 330 Mhz junk band and are right in the middle of the Military A-Band. Doh! Unfortunately, they are also Part 15 users of the spectrum there, and are secondary users of those frequencies - they must not interfere and must accept any interference they experience. Double Doh!!
-- You are in a maze of little, twisty passages, all different... --
Key fobs, RF remotes and Garage door openers are using the 330 Mhz junk band and are right in the middle of the Military A-Band
We had rock bands come to us (near a Canadian base).
About 3-4 miles from the hotel was a NORAD RADAR. The pulse from the RADAR would manifest itself as a "BZZT" in the band's amplifiers (If was funny seeing the band try to locate the source.....). Heck, you could hear it on your car radio.
Big wattage is NO joke. The spill-over into other freqiencies is a fact of life (anyone with a CB will know it as cross-talk).
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I am a programmer. I am paid to produce syntax not grammar. Deal with it.
In the Navy they use a system called a Red Tag systems. When you are working on equipment and you must kill the power to it you put a Red Tag on it and anyone who violates a red tag suffers severe consequences (up to court martial) So if your dad did not tag the fuse box and decided to work on the radar system (live radar will kill you if you stand in front of the dish) he was not following navy procedure.
I've seen the outcome when the Red Tag procedure is not followed, it cost a friend of mine his hand.
Sorry, teleporters just kill you and then make a copy. A perfect, soul-less copy.
I work for Chamberlain who makes the Liftmaster and Chamberlain garage door openers. Our newest units just started using 420MHz. I had an old 330MHz unit and my range sucked, so I installed a 420MHz logic board and my range more than doubled. I live right next to Davis Monthan AFB which gives me all kinds of RF interference. I suggest to anyone who has trouble with their Chamberlain, Liftmaster, or Sears GDOs then call Chamberlain and find out if you can upgrade to the 420MHz boards on your model. The price of the boards is crazy expensive ($70), but we here at Chamberlain can give discounts at our leisure. We sometimes will give one out for free if the conditions are right. (WHINE, WHINE, WHINE, "But I can't afford THAT!", "$70?!, The whole unit was $150!", etc)
A lot of posts to reply to, but basically, Naval Ship radars function on lots of bands, not exluding the A Band, mentioned above.
Aircraft carriers have a good deal more power than one would think, and certainly more than a Tico, which is about medium size. One thing to note is that there is no "Medium" size for Navy ships, there are small guys, and big guys. CVN, LHD and LHA are going to have more power because they are bigger...the LHD I served on had 5 primary generators rated at 2500kW a piece, plus another 2 backups at 2000kW each. LHAs are similar, but CVNs have even more, mainly because they have fuel to burn, being nuclear.
Oddly, in the radar category, its only the smaller ships in the Cruiser Destroyer community that have phased array radars, which have higher output than those found on other ships. On carriers, the primary high output radar is the SPS-48E (a rotating radar, as all are, with the exception of the SPY-1 series), and has such power because it is an Air Search radar that scans in 3-D. There are ranges at which we are required to turn off our radars in vicinity of land, but this is soley at the attentiveness of the watchstander, and we frequently got reports during Operation Iraqi Freedom thaty our 48E was jamming the airport radars in Kuwait, and we were requested to lower the power output.
Anyway, a carrier pulling into town running a 48E could certainly jam such devices, but more frequently we get reports that devices start *operating* without warning (garage doors opening, etc.) Certainly you'd see these things more often if you worked on a Naval Base, since lots of ships tend to pull in and out there.