I almost missed this message for some reason but
discovered it when moving messages from one folder to another.
"Mrs. Lynnette Annabel Smith" writes:
> Ah yes, memories! I still remember our old monochrome TV, we didn't go
> colour until about 1969 because our antenna system wasn't compatible.
I would almost bet money that was the 405-line system.
There would have still been a huge number of them around in 1969
what with color only 2 years old. Your antenna would have been
rather large compared with the almost tiny antenna needed for
UHF reception.
> When BBC2 started transmitting they put it on UHF as I remember and the
> old VHF antennas had to be replaced. Also, my parents objected to paying
> the higher license fee for a colour TV. Eventually they were pushed into
> it by their children's rebellious and persistent complaining. But colour
> TV was a revolution to us in those days.
Of course, American children would never have pressured
their parents to spend more money on a color TV. And, if you
believe that, I have a certain bridge in New York City which can
be yours for an amazingly low price.
> What I do remember seeing from time to time is interference from European
> TV channels when conditions were right, usually in the Summer. Gordon
> tells me that he used to enjoy those times because it meant that the FM
> broadcast band became a very interesting place to listen and also his VHF
> and UHF amateur radio adventures became fun as well. He's telling me that
> in August 1985 there was a massive massive lift and he was working
> American stations on 144.300 MHZ single sideband and right down at the
> bottom end of the band on CW. He says he even worked a couple of stations
> from California and one from somewhere in Canada on FM at the top end of
> the European band. He thinks that in the states the 2m band goes from
> 144.00 to 148.00 MHZ.
That is Correct.
> Over here it's only 144 to 146 MHZ. Anyway, that's
> got him talking about something I never knew. :)
Oh yes! All of us radio amateurs live for something like
this.
Don't worry about all the little details, but our
atmosphere is like a layered cake. We live in the troposphere
which extends to about ten miles above our heads and is
responsible for what we call surface weather such as clouds,
rain and snow, and thunderstorms. It doesn't normally do much to
radio except for the static in lightning storms, but there is an
effect called tropospheric ducting which occurs when there is a
hard boundary between warm, moist air and cold dry air. This can
bend radio signals the same way that glass and water bend light
and it effects signals in VHF, UHF and even microwaves, causing
them to travel for sometimes over a thousand miles instead of
just shooting off in to space as they normally would.
Here in the middle US, we don't get many tropo openings
as they are called, but we still do get them and they are
spectacular. You might hear signals on VHF and UHF from 4 or
5-hundred miles away or more. The UHF television channels
suddenly fill up with signals from surrounding states and
two-way radio systems began to experience strong and usually
un-wanted neighbors they weren't supposed to have.
Above the troposphere and stratosphere, we begin the
ionosphere or what some refer to as the magnetosphere. It starts
about 60 miles above us and extends outward to maybe 300 or 400
miles or 600 or 700 KM. By this point, the air is almost
nonexistent and is mostly stray molecules of oxygen, nitrogen
and other air gases. The sky is pitch black all the time and you
are in near space but those atoms and occasional molecules
become ionized or charged by the Sun and begin reflecting radio
signals back to Earth.
The AM radio broadcast band plus HF amateur and short
wave frequencies can travel around the world due strictly to
this ionization in that very thin air.
If the Sun is active, one particular portion of the
outer-most ionosphere can reflect signals up to and including
the lowest VHF amateur band known as 6-meters. That's how we
used to be able to hear BBC1 television here in the United
States.
That same layer of the ionosphere is normally not quite
that active, but on any day, it probably will bounce signals
back to Earth up to 18 or 25 MHZ. It is totally variable so I
could say just about anything about the ionosphere and be right
or wrong at any time.
Another layer, the one starting about 60 miles above us
is called the E layer and normally is what lets us hear far-off
stations on the AM radio after dark. On occasion and nobody
knows just why yet, it really becomes tremendously active around
the times of the Summer and Winter Solstices. It begins to
reflect signals in VHF with stunning strength. The FM broadcast
band suddenly fills up with strong signals from hundreds of
miles away, maybe even over a thousand miles on occasion.
Then, like the mythical town of Brigadoon, the party
dies out and everything returns to normal.
You mentioned Closed-Captions. I think that warrants a
separate message.
Take care,
Martin
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