Distinguishing RF from IR [was Re: What is the highest radio frequencyused for radio astronomy?]

[Green Xenon [Radium]]

On Aug 30, 4:33 am, gwatts <gwa...@frontiernet.net> wrote in
http://groups.google.com/group/sci.a...7b6c89acacf15d :









There difference between IR communication and RF communication is that
while both can be wireless, the former can only be used for point to
point communication while the latter doesn’t have that restriction.

Think about it.

Using a remote control for your TV. If your remote is IR you must aim
the remote at the TV in order to make the changes you want [such as
changing the channel or turning the TV on/off]. If the remote is RF,
then you make those desired changes to the TV regardless of what
direction you point the remote at -- you even control the TV from a
different room provided that are no metals blocking the radio signals
between the TV and the RF remote.

Using the above definition, what is the highest-frequency of
electromagnetic spectrum that is considered “radio” and not IR?

Equally interesting -- what is the highest-frequency of radio that is
not opaque to the earth’s atmosphere?


Thanks,

Radium

[Odysseus]

In article <46f9ba12$0$7459$4c368faf@roadrunner.com>,
"Green Xenon [Radium]" <glucegen1@excite.com> wrote:

<snip>

I think that's a gross oversimplification, an attempt to make
black-and-white a question that encompasses shades of grey.


Radio/microwaves penetrate more substances than IR, but they're no more
or less directed. Substitute a radio-opaque obstacle (e.g. a Faraday
cage) for the wall or body that blocks your IR remote, and the situation
is pretty well the same. Have you never heard a car radio lose its
signal when the vehicle passes under a reinforced-concrete structure?

Take your remote out of its casing and I bet the IR emission becomes
nearly omnidirectional ... OTOH masers emit coherent beams of RF energy.

--
Odysseus

[jimp@specsol.spam.sux.com]

In rec.radio.amateur.space Green Xenon [Radium] <glucegen1@excite.com> wrote:










Babbling nonsense.

The directivity of RF and light sources is determined by the emitting
structure, the antenna if you will.

RF at low megahertz can be "point to point" with a sufficiently
directive antenna and light can be omnidirectional.

Ever seen a light bulb or candle?


I suggest you do.

<snip remaining nonsense>


--
Jim Pennino

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[Sjouke Burry]

jimp@specsol.spam.sux.com wrote:


You are trying to educate a troll.
Trust me, its better to leave them under a bridge.
Look at the list of groups, and google for his name.

[jimp@specsol.spam.sux.com]

In rec.radio.amateur.space Sjouke Burry <burrynulnulfour@ppllaanneett.nnlll> wrote:



I'm well aware he's a babbling idiot.

I just like to rub his nose in it once and a while.

--
Jim Pennino

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