Speaking of interference (BPL)

On 07 Nov 2003 23:14:56 GMT, (Teacherjh)
wrote:


Should we as pilots be concerned as to what this can
do to our nav radios?


Yeah, I think so. More benign stuff (cable TV lines) messes up my car radio,

You need to get a few hams to drive around running 2-meter mobiles.
It wouldn't be long and the cable leakage would get cleaned up.
I've only seen a few cases of bad cable leakage. When it leaks that
bad it usually bothers reception as well and customers complain.

On occasion I listen on 145.25 MHz which is an amateur frequency. It
also happens to be the audio subcarrier for cable channel 18. I did a
demonstration over in the city of Alma MI for the cable company. With
my HT I could blank all their monitors in the distribution center
which of course blanked everything to their customer base as well.
They remarked that it was only because I was so close. So I went out
to my car which was well over a 100 yards to the west. The HT was
still bothering a little, but when I keyed my mobile station their
whole system went blank. When I came back into town the next day
nearly all the leaks were fixed. The following day I could not find a
one.

One thing that bothers them is customers who hook up an outside
antenna without using a switch. It leaves the antenna tied to the
cable and it does a really good job of picking up amateur radio on
2-meters which then gets fed to all customers down the line.

sometimes to the point I can't use it and would be forced into a satellite
radio subscription if I weren't against it on principle, let alone against
being forced into it by the same forces that benefit.

I'd complain to the FCC. They are pretty good at coming down on cable
companies who are reluctant to keep things fixed.


BPL makes no sense to me - power lines are filtered to get rid of the HF stuff,
and that's exactly what broadband needs.

Maybe five miles up it's no biggie, but on approach, when you -really- need it,
that's when it'll bite you. I think this is a far bigger problem than
cellphones on airlines.

That's the part that worries me. They may be able to filter out the
FM and aviation bands. The cut off is *supposed* to be below the FM
broadcast band, but high speed data with steep rise and fall times
develops some pretty strong harmonics, even if it is spread spectrum.

OTOH, I'm assuming if they use the same HF frequencies as the ham
bands it will only take one or two running high power to cause
problems to BPL. (again, even if it is spread spectrum)

In a number of states the State Police still use some frequencies
around the 40 to 50 MHz range.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Jose