Thanks for the posting. As an incidental comment, many keyless vehicle
entry systems use 315 MHz, another "military" frequency.
BTW: The situation cited in the article also happened a number of years ago
in the San Diego area when several ships from the Pacific Fleet returned to
port. I suspect that at least some of the radio systems referred to in the
article are using the new generation SDRs - Software Defined Radios - the
most notable being the JTRS system. Those radios have a basic hardware
design that allows them to operate on ANY frequency in the range of 2 MHz
to 2000 MHz, but software is used to define the actual operating range of
any given system. Thus, I think we can expect to read about more of the
same for quite awhile.
73, Dale
WA9ENA
> [Original Message]
> From: Steve Sacco NN4X <nn4x@embarqmail.com>
> To: <rfi@contesting.com>
> Date: 12/11/2010 7:16:27
> Subject: [RFI] Crossed Signals (news story)
>
> RFI is everywhere.
>
> 73,
> Steve
> NN4X
>
> <http://www.strategypage.com/htmw/htecm/articles/20101209.aspx>
>
> Crossed Signals
>
> December 9, 2010: Recently residents of Bremerton, Washington State
> (northwest U.S.) were warned they may have problems with wireless
> electronics (especially garage door openers and keyless care remotes) as
> the U.S. Navy tests electronic systems on the carrier USS Stennis. The
> ship has undergone some refurbishment recently at a Bremerton shipyard,
> and the electronic systems need some testing before the ship puts to sea.
>
> This is not a new problem, which is why the navy put out a warning this
> time. Six months ago, the U.S. held naval exercises off Hawaii. But
> first, many of the ships involved tested electronics while docked,
> before going to sea. That?s when all the reports came in about garage
> door openers in the area not working. It was interference from the
> military electronics. But no prior warning was put out. Someone should
> have known better. Even new civilian broadcasting equipment can be a
> problem. Late last year, U.S. military personnel and their families in
> Japan were warned not to use a number of American wireless devices (baby
> monitors, cordless phones and so on), because they use frequencies too
> close to those allocated to cell phone service in Japan.
>
> But it?s military electronics, which usually don?t operate near a lot of
> civilians, that cause the most difficulties. This sort of thing can be
> traced back to decisions made years ago, that have only recently turned
> into a problem. For over half a century, one of the radio frequencies
> reserved for military use in the United States (380-400 megahertz band),
> was also used for some consumer electronics. Starting in the 1980s,
> manufacturers of garage door openers were allowed to use the 390
> megahertz frequency, because the openers were very short range (low
> power) and unlikely to interfere with military radios (or vice versa).
> But a new generation of military radios has changed all that, by sending
> out a very powerful 390 megahertz signals. Six years ago, garage door
> openers were sudden being activated by the new military radios in the
> United States.
>
> The problem first showed up as new military radios, using the 390
> megahertz frequency, were installed on military bases. By now, most
> bases are using the new radio system. While the Department of Defense
> believed that the new radios only made garage door remote control
> systems inoperable, thousands of users reported seeing garage doors open
> and close by themselves. While the garage door system manufacturers were
> using the 390 megahertz frequency unofficially (but with the knowledge
> of the government), they had to change their equipment to use another
> frequency. But before the gear using the military frequencies could be
> replaced. Over 50 million garage door systems (those within 80
> kilometers of a military base), were involved in the mysterious
> malfunctions.
>
> There are increasing problems like this, as more wireless equipment
> comes into use, and the military makes more use of frequencies they have
> long ?owned? but not really worked hard. It's an old problem, and was
> first noted on a large scale during the 1991 Gulf War. Here, there was a
> large concentration of military equipment from all the American military
> services, and foreign armed forces as well. There were several
> unexpected incidents where frequencies collided in unexpected ways.
> There was some of this again in Iraq after 2003. There will be more
> conflicts like this, and some of it will be in combat, with deadly
results.
>
>
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