RF through water question

[Jan Panteltje]

On a sunny day (Thu, 13 May 2004 19:28:39 -0700) it happened DarkMatter
<DarkMatter@thebarattheendoftheuniverse.org> wrote in
<5mb8a0tae3aq17kuds9k6mv6mk58rlrsgv@4ax.com>:

On Thu, 13 May 2004 06:17:53 GMT, Repeating Rifle
SalmonEgg@sbcglobal.net> Gave us:



This use of a marker is a new one for me, but makes reasonable sense. The
use of the green marker that was publicized over five years ago was to
improve the fidelity over that of the digital sound as extracted from the
unmarked CD. That is what I consider to be koo-koo.


It is.
Electronically and mechanically and optically and physically yes.

But the psychological effect is real.
man goes out and buys green marker, spends money, talks with people
how he will use that marker, people say: 'OOOOWW I did not know that'
No man feels good, sits down, marks CD or DVD and is more relaxed.
As his muscles are more relaxed, and the grinding sound of the teeth has
stopped a bit, the signal to noise has increased dramatically, and he
can really enjoy.
I have green CD safe marker for sale, starting at 750$ a piece (ex tax).
The blue ones are already available to, for blue light DVD it is already
here.
Those need to be listened to with orange glasses btw, to avoid visual
feedback.
JP

 

[Carl D. Smith]

On Wed, 12 May 2004 04:36:27 GMT, "The other John Smith"
<jocjo-john@yooha.com> wrote:

Yes. About 10 or so years ago, when I worked for a company who made variable
speed motor controllers, an engineer with Continental Electronics called and
asked about our 250 kW inverters. During the question/answer process, it
came out that he wanted an output of about 250 kW with frequency variation
of something less than 60 Hz to near 100 Hz to communicate with submarines.
Huh? I said, you can't pass any information with a carrier at that
frequency. He said it all depends on how it's modulated and how much time
you take to decode it. That shut me up.

I'll never forget that phone call.

This reminds me of another example of the extreme end of
communications theory. A couple years ago I interviewed with a
company that makes remote readable electric meters. They put a
module in the bottom of the meter that reads and counts the
rotation of the disk and sends a signal back to equipment placed
at certain places around the power grid to collect meter
readings.

The signals were sent over the power grid in a band of something
like 10 or 20 Hz centered around 60 Hz so it could get through
transformers. They crammed thousands of parallel data channels
hundredths of a Hz apart into that band. Time to transmit ONE
BIT was something like 20 minutes.

They claimed in testing they had received the signal up to 100
miles away.

 

[John Gilmer]

This reminds me of another example of the extreme end of
communications theory.

About 30 years ago I worked with a fellow who joked: "There are just as
many octaves BELOW one hertz as there are ABOVE one hertz."