"Telamon" wrote
Yes that is true that the fundamental by itself will not produce
harmonics of lower frequency but the fundamental is being modulated by
data so mixed products of variable data transmitted mixing with the
carrier will produce frequency energy above and below the fundamental.
If you have long strings of ones or zeros the mixed frequencies will be
as low as the inverse of the period of low frequency data rates.
____________

The spectrum occupied by a data pulse is dependent on the rise and fall
times of the pulse, not on the pulse duration. If the rise and fall times
are constant, spectral bandwidth also will be constant. Only the
distribution of energy within that spectrum will vary for pulses of
different lengths (half-amplitude durations).

A familiar example of this is the "click" created in radios when a nearby
electric light is switched on or off. When the switch contacts make and
break, they create a current transition across a short time interval --
which generates a wideband RF spectrum. This RF energy is radiated by the
AC wiring, and some of it is received and detected by the radio.

RF

Visit http://rfry.org for FM transmission system papers.

In addition, most homes are now wired for
cable, which is much better shielded than your basic HF antenna.

not true. My radio scanner proves that the cable companies are not shielded.

Even when driving to the next county over, which is a different cable company,
I still pick up the cable tv transmissions on my scanner, through the air.

And even driving to the next city over, which is a third cable company, I still
pick up the transmissions through the air.

NOne of them are shielded.

It ruins trying to listen to the communications bands on a bunch of frequencies
above 30 MHZ.

Reporting it doesn't do any good, as all of the cable companies refuse to fix
it.

HF, and 1000uV for television). In addition, most homes are now wired for
cable, which is much better shielded than your basic HF antenna.

In addition to the cable leak interfering with listening to communications
above 30 MHZ, it also interferes with listening to AM broadcast and shortwave
bands even worse because of all of the buzzing caused by it on AM and
shortwave.

Just to make s ure that the problem wasn't in my radio, I also checked my other
radios (AM and FM bands).

The buzzing was still present on the AM radio on every radio I have. So the
problem was definitely not in my radio.

When I do get far enough out oif the area, the buzzing stops and AM can be
picked up mnormally.

However, I normally don't drive out of the area that far.

I usually stay either at home or within the area.

I just remembered when the cable leak interference started here at my home.

Early last year, I still recieved AM and shortwave as normal,from home, without
any of that type of interference, no buzzing.

Then later last year, the cable company came and switced all of their wires
around to fiber-optic cable to improve reception.

Well, that's what the cable guys working on the lines said they were doing,
switching the cable to fiber-optic cable.

And that was right when I started having the cable leakage problems, from home.

Ever since they switched to fiber-optic cable is when I started having all of
the interference problems of buzzing on AM and shortwave radio when listening
from home, making the bands almost totally useless.

I'm guessing the other cable companies in the area are also using "fiber-optic
cable".

"Stereophile22" wrote in message
...
In addition, most homes are now wired for
cable, which is much better shielded than your basic HF antenna.

not true. My radio scanner proves that the cable companies are not
shielded.

Even when driving to the next county over, which is a different
cable company,
I still pick up the cable tv transmissions on my scanner, through
the air.

And even driving to the next city over, which is a third cable
company, I still
pick up the transmissions through the air.

NOne of them are shielded.

It ruins trying to listen to the communications bands on a bunch of
frequencies
above 30 MHZ.

Reporting it doesn't do any good, as all of the cable companies
refuse to fix
it.

Tell them you're getting their programming for free because
they have leaky systems. That'll change their tune real
fast. Time Warner locally has been well known for being
exceptionally greedy about that sort of thing.

--Mike L.

In article ,
"Richard Fry" wrote:

"Telamon" wrote
Yes that is true that the fundamental by itself will not produce
harmonics of lower frequency but the fundamental is being modulated by
data so mixed products of variable data transmitted mixing with the
carrier will produce frequency energy above and below the fundamental.
If you have long strings of ones or zeros the mixed frequencies will be
as low as the inverse of the period of low frequency data rates.
____________

The spectrum occupied by a data pulse is dependent on the rise and fall
times of the pulse, not on the pulse duration. If the rise and fall times
are constant, spectral bandwidth also will be constant. Only the
distribution of energy within that spectrum will vary for pulses of
different lengths (half-amplitude durations).

Snip

Yes and that would be the case for NRZ data or non return to zero data.

--
Telamon
Ventura, California

On Mon, 15 Nov 2004 16:40:42 -0500, "Michael Lawson"
wrote:

Tell them you're getting their programming for free because
they have leaky systems. That'll change their tune real
fast. Time Warner locally has been well known for being
exceptionally greedy about that sort of thing.

More likely they'll threaten to sue your ass for "theft of
services".

"Telamon" wrote

Yes and that would be the case for NRZ data or
non return to zero data.
___________

Once past the pulse transition, NRZ "data" is nothing but a different value
of DC -- the bandwidth of which is infinitely small.

If NRZ data is amplitude modulated onto a carrier via a DC-coupled
modulator, then the effect is to change the amplitude of the carrier from
one steady-state value to another. The occupied spectrum is infinitely
small for steady-state carriers.

For frequency modulation, DC-coupled NRZ data will change the carrier from
one frequency to another, each of which will be infinitely small during
steady-state conditions.

RF

"dxAce" wrote in message
...


Brenda Ann Dyer wrote:

"Frank Dresser" wrote in message
...

" Radio Flyer" wrote in message
.. .


It's true, It will cover the tv bands up to 80 MHZ except for
74.8-75.3


Gee, that's something to think about, isn't it? I mean ABC, CBS, NBC
and
FOX aren't in a big panic about BPL, are they? Why the hell should
SWLs
worry more than the networks?

BPL looks like another Y2K crisis, to me.

TV stations aren't concerned (yet) about BPL because the signal levels
needed to receive snow free television are on the order of 50 times
higher
than those to receive a listenable signal on a good HF receiver (20uV for
HF, and 1000uV for television). In addition, most homes are now wired for
cable, which is much better shielded than your basic HF antenna.

Well of course. Why would one want a HF antenna to be shielded?

dxAce
Michigan
USA

You may want it to be shielded when BPL is nationwide

Brenda Ann Dyer wrote:

In addition, most homes are now wired for
cable, which is much better shielded than your basic HF antenna.


I shielded all my antennas two years ago. As a very strange
coincidence, I haven't received a signal since..I mean, just what are
the odds of THAT happening??

Now you tell me that cable is even BETTER shielded. Just what are they
paying for? Is there some sort of trick 3-D effect if you stare at the
screen long enough? Whatever it is, it sure doesn't work for me...and
yes, I've tried squinting.





mike (..i think i'm going snow blind..) II