In rec.radio.amateur.antenna Jeff Liebermann wrote:
On Sat, 7 Jul 2007 14:44:28 -0600, "Bob Myers"
wrote:

"Jeff Liebermann" wrote in message
.. .
Digital is nothing more than an analog device with too much gain and
hysteresis, where the output is stuck at either high or low. Dig deep
enough into any digital contrivance, and you'll find analog devices
operating in this way. The real world is analog. (Just ask any
analog engineer).

We've been here before, too. The real world is the real world
- it is neither "digital" nor "analog," which are terms used (at
least when used correctly) to refer to two methods of encoding
information about (or describing) the real world or some specific
real-world parameter.

In college, the senior electrical engineering class was polarized into
two camps, analog and ditital, largely by their choice of senior
projects. I made the mistake of designing a project that straddled
both camps (Secode Selector using RTL and DCL). Life was hell. The
debate came to a grinding halt when someone noticed that DNA sequences
were digital. So, if you dig deep enough into an analog world, you
eventually hit a digital bottom. I'll call it a win for whichever
side pays better this week.

And in case it makes you feel better about the answer, yes, I am
(or at least have been) an "analog engineer." (Or rather, an
engineer involved in the design of "analog" circuits and systems.)

Ditto. I did RF design for various companies, which in the 70's and
80's was mostly analog (FM, AM, SSB). For obvious reasons, I tend to
favor the analog view of reality. Now daze, it's all conglomerations
of analog and digital techniques and infested by longer acronyms.

Until the graviton is proven, the world is analog, at which point
I will switch positions.

--
Jim Pennino, analog engineer until proven otherwise

Remove .spam.sux to reply.

wrote in message
...
Until the graviton is proven, the world is analog, at which point
I will switch positions.

OK, so if the world is "analog" - it's an analog of
what, exactly?

Bob M.

So, I should start investing in all the analog am/fm/tv/etc. stations
which appear doomed ...


Never bet against new technology...

denny / k8do

On Fri, 06 Jul 2007 01:25:02 GMT, wrote:

In rec.radio.amateur.antenna Radium wrote:

snip

Agreed, static magnetic fields tend to decay rapidly as you move away
from them. However, alternating magnetic fields continue to propogate
by generating alternating electric fields of the same frequency. These
alternating electric fields, in turn, generate alternating magnetic
fields. The cycle keeps repeating.

Nonsense as stated.

No, it's just a qualitative restatement of Maxwell's theorems.
Changing e-field makes H-field, changing H-field makes e-field, and
they toodle off into the sunset at the speed of light.

John

On Thu, 12 Jul 2007 08:52:24 -0700, John Larkin wrote:
On Fri, 06 Jul 2007 01:25:02 GMT, wrote:
In rec.radio.amateur.antenna Radium wrote:

snip

Agreed, static magnetic fields tend to decay rapidly as you move away
from them. However, alternating magnetic fields continue to propogate
by generating alternating electric fields of the same frequency. These
alternating electric fields, in turn, generate alternating magnetic
fields. The cycle keeps repeating.

Nonsense as stated.

No, it's just a qualitative restatement of Maxwell's theorems. Changing
e-field makes H-field, changing H-field makes e-field, and they toodle off
into the sunset at the speed of light.

Exactly. The Yin calls forth the Yang, and in their cosmic dance, they
create Manifestation. ;-)

Cheers!
Rich
--
For more information, please feel free to visit http://www.godchannel.com

On Thu, 05 Jul 2007 18:07:22 -0700, Radium
wrote:

On Jul 5, 3:19 am, "Mike Kaliski" wrote:
"Radium" wrote in message

oups.com... Hi:

Can the Spin Exchange Relaxation Free Magnetometer be used to receiver
distant AM radio signals in which the carrier frequency is 150 KHz?
What if the carrier frequency is 44.1 KHz [for the same reason CDs use
a 44.1 KHz sample rate]? 40 KHz?

Thanks a bunch,

Radium

Radium,

The simplest answer is no. The reason is that you specify 'distant'. The
strength of a magnetic field decays rapidly with distance and for most
practical purposes, 800 metres would be a maximum typical detection range
for man made magnetic fields as opposed to natural fields like the earth's
magnetic field.

A radio signal has an H-field component that doesn't decay like a
near-field magnetic effect. That's why AM radios use loop or rod
antennas that pick off the magnetic component of the em wave.


Radio waves are made up of electric and magnetic fields.

Yes.


Couldn't the Spin Exchange Relaxation Free Magnetometer receive the
magnetic portions of AM radio waves at the carrier frequencies I
described? If not, why?

This might be made to work, but gaseous resonances like this are
usually very low bandwidth detectors, often sub-Hz, so sensitivity at
tens of KHz would be pitiful.

RF Reception in this frequency range is dominated by atmospheric
noise, so a super-sensitive detector doesn't help. A simple tuned loop
antenna and a decent front-end amp, a jfet maybe, is as good as you
can do.

John