Back in , I believe it was the 1990s Chrysler had a V-6 in a new line of
cars. (Cab forward?) The computers in those cars from a block distant
could over power our repeater just 2 miles distant. I was interested in
purchasing one, but discovered the computer signal on a test drive. The
dealer worked with me to pinpoint the problem. He was very helpful. It
turned out to only be on the high performance configuration of cars with
that engine. However the response from Chrysler was basically. Tough!
Live with it. Two years later they still had the same problem, but it
was eventually fixed. In the mean time I purchased a Trans Am.
Industry is learning, but I believe the learning process still is
ongoing with new RFI sources constantly showing up.
Had it not been for the ARRL, BPL would have become a reality. I
believe it took many hours (over years?) for that process which Ed
should be able verify. Thanks for the hard work Ed.
Having been an instrument rated pilot and heavily involved, I'm quite
familiar with the following about 5 to 6 years ago.
The same is true with LightSquared and their ground based wireless
augmentation system which would have placed many ( I believe it was to
be 40,000.) 40 KW ground based transmitters next to the GPS satellite
down link frequencies. Based on their information provided to the FCC
that there would be no interference, the FCC granted temporary approval
for the installation of ground transmitters even though the satellite
industry and aviation groups provided information that these
transmitters would (not could) create dangerous interference to aircraft
using GPS navigation, particularly in high density traffic areas around
major airports and cities. I believe you will find that the FCC
violated their own rules in the case of authorizing (even on a trial
basis) of LightSquared's ground based transmitters. They went so far as
to provide the FCC with what was basically false information. Only
the massive input from other Federal departments, industry, and
individuals finally stopped the implementation. There were likely to be
Billions of dollars at stake in the future. The whole story including
reason, makes for interesting reading, but not here.
How it was done: Quote from "The Left Seat": " the FCC issued the
wavier for a ground based system in the satellite bands against the
concerns and recommendations of the Department of Defense,
Transportation, and Homeland Security AND its own guidelines. The NPRM
was issued in such a manner that the comment period was far shorter than
normal. On top of that the accelerated test schedule, LightSquared is
the only one who will present the data to the FCC, and they are required
to have equipment in place “IF” the OK is given." Links were provided
in the blog.
That it went away quietly with no fanfare raises questions. You almost
have to go to the pilot groups to find out the real details.
"LightSquared ground based transmitters to interfere with GPS" as search
criteria did produce results, but much of the drama is no longer there,
although I did not follow all of the links. The "Left Seat" blog
should provide some interesting background.
In these instances Industry was anything but proactive. There will
always be companies like LightSquared pushing the limits.
Off shore companies producing these little switching power supplies
aren't worried as the FCC can go after the importers and chains selling
their products. Even prevent the importation of their products, but they
can easily change their name or names. Until the FCC tests random
samples of every one of these products on a continuing basis, they will
be imported by the millions. I don't think the FCC has near the
required manpower to even think about undertaking such a job, or the
money to hire it done. Hence the "Case by case" approach. We are few in
relative numbers, so the numbers without complaints and happy customers
keep these RFI generators coming in and raising the noise floor ever so
slowly. Eventually you will need to move well into the country to even
think about weak signal work on HF, or even higher. Hopefully things
will change for the better.
I have worked quite a few AU signals on six that were so weak they
didn't even show on the scope which was a straight line with the noise
being barely visible. I could only hear a slight change in the
background noise (AU buzz) with CW. Even raising the noise floor a db
would likely make that impossible. But what do we do when the RFI is
caused by thousands, or more of these devices? It's like trying to find
a single blade of grass in an over grown pasture. Removing the one is
quickly over shadowed by the thousands that take its place.
I never noted light pollution until we lived way out in the country. One
night I stepped out on the front porch, looked up at the night sky and
was astounded by the mass of stars, yet it was so dark, I almost fell
off the porch. Like the noise floor slowly creeping up, I never noticed
the light pollution until I had something with out it for comparison.
In many ham cases we only have our old memories on which to rely.
We can provide RFI data for individual items, but when produced by a
cottage industry spread over a very wide area, there is likely to be
little consistency, even between light bulbs on the same shelf. So how
can we as individuals, or a group provide meaningful information when
it's quite possible a test lab could end up with a case of perfectly
quiet samples? Again, we are back to the case by case problem.
Eventually, the sheer volume will make automated, mass production
cheaper than the cottage industry. Then we will see consistency but who
On 8/3/2015 2:50 PM, Hare, Ed W1RFI wrote:
A billion dollar corporation is going to stand silent while the FCC either
forces their product to be
removed or re-engineered at great expense?
The automotive industry also has been very pro-active about avoiding EMI
problems involving Amateur Radio, developing standards for the installation of
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