AM Radio Receiver based on Spin Exchange Relaxation Free mechanism

[Warren Oates]

Well, the WWVB transmitters are in Colorado. I'm in California. The
signals did not arrive via bus, truck, airplane, train, or carrier
pigeon. Lacking any other obvious transportation methods, I suspect
they arrived by electromagnetic propagation.

Someone should put together a digest of some of your more pithy sayings.
I'm still chuckling over the one about "time is nature's way of making
sure things don't all happen at once" (that's from memory, I'm way too
lazy to actually look it up).

This swarm thing, is this connected to some modern (or maybe not)
theories about "nothing is really analogue, everything is digital in its
own way"?

 

[Jeff Liebermann]

Someone should put together a digest of some of your more pithy sayings.

It's been done. One of my surviving former friends assembled such a
collection under the title of "Quotations of Chairman Jeff". It was
presented to me in manuscript form at a ceremonial roast (long story,
don't ask).

I assembled some of my early computah support horror stories and tech
poetry at:
<http://www.LearnByDestroying.com/nooze/support.txt>
<http://www.LearnByDestroying.com/poetry/poetry.htm>
I've stopped collecting such stories and writing poetry for fear that
I might stop, think, wake up, and immediately abandon the business for
something more sane.

I'm still chuckling over the one about "time is nature's way of making
sure things don't all happen at once" (that's from memory, I'm way too
lazy to actually look it up).

It's not original. "Time is natures way of keeping everything from
happening at once." I stole that from an engineer friend that worked
on Cesium clocks for HP. It was hanging on the wall in his cubicle.
Someone had scribbled under it "Take your time, but leave mine alone".
I believe the original quote was from Woody Allen, but there may have
been earlier versions.

This swarm thing, is this connected to some modern (or maybe not)
theories about "nothing is really analogue, everything is digital in its
own way"?

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).

 

[Bob Myers]

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.

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.)

Bob M.

 

[Jeff Liebermann]

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.

 

[Bob Myers]

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.

I've tended to take a slightly different approach, which I hinted
at in my earlier response. It generally gets me some odd looks and
a "no, that can't be right" sort of reply, but I find it IS a helpful way
to look at things - at the very least, a different perspective that can
give you some new insights into how all this stuff "really" works.

As I'd said, I tend to think of the "real world" as just that - it is
neither
"analog" nor "digital." From this perspective, those two terms simply
point to different means of encoding information for communication or
storage. I find that, all too often (again, at least from this
perspective),
we tend to use the words "analog" and "digital" when what we really
mean to say are things like "linear," "continuous," "discrete," "quantized,"
and so forth. Fundamentally, I tend to see "analog" as simply meaning
" a system whereby information about a given parameter is encoded
by causing some other parameter (voltage, for instance) to vary in an
analogous manner." It doesn't necessarily mean "linear" or even
"continuous." Similarly, "digital" winds up with an even simpler
definition - "information encoded in the form of digits (numerical
values." I've never found a situation where I couldn't use these words
with those interpretations. And like I said, it IS often helpful - for one
thing, you wind up with a much better feeling for the real advantages
and disadvantages of "digital" and "analog" systems. (And you also
wind up not worrying about certain sillinesses, like whether power
systems are "analog" or "digital" - since the world no longer has to
be divided up exclusively as one or the other.)

Some people can't seem to wrap their minds around such things, but
then, I'm not really going to worry about that.

Bob M.

 

[Jeff Liebermann]

I've tended to take a slightly different approach, which I hinted
at in my earlier response. It generally gets me some odd looks and
a "no, that can't be right" sort of reply, but I find it IS a helpful way
to look at things - at the very least, a different perspective that can
give you some new insights into how all this stuff "really" works.

That would be nice, but that's not the way engineering works these
days. At some point, most designers end up being either analog or
digital. Except in systems design, it's a rare engineer that can
function well in both camps. The result is usually microprocessor
acting as a marginal replacement for an op amp, or an analog circuit
that can't work in the real world because the tolerances and error
accumulation far exceed what could be done with digital. If you only
have a hammer, everything looks like a nail.

As I'd said, I tend to think of the "real world" as just that - it is
neither
"analog" nor "digital." From this perspective, those two terms simply
point to different means of encoding information for communication or
storage. I find that, all too often (again, at least from this
perspective),
we tend to use the words "analog" and "digital" when what we really
mean to say are things like "linear," "continuous," "discrete," "quantized,"
and so forth.

I just hate to agree with anyone, but you're correct. Analog/Digital
have become so vague that more specific terminology is required.
Still, the terms will not go away and must be dealt with as they
appear. Try searching Google for "analog engineering" and "digital
engineering" with the quotes. It's going to take a while for all
those hits to go away and be replaced by something more specific.

Fundamentally, I tend to see "analog" as simply meaning
" a system whereby information about a given parameter is encoded
by causing some other parameter (voltage, for instance) to vary in an
analogous manner." It doesn't necessarily mean "linear" or even
"continuous." Similarly, "digital" winds up with an even simpler
definition - "information encoded in the form of digits (numerical
values."
Agreed.

I've never found a situation where I couldn't use these words
with those interpretations.

Now you've done it. I'll be spending most of the day dreaming up
situations where the type of information encoding is ambiguous.
Offhand, quantum mechanics doesn't it either world, but then it
doesn't really fit any sane world, so that's not a good example.

And like I said, it IS often helpful - for one
thing, you wind up with a much better feeling for the real advantages
and disadvantages of "digital" and "analog" systems. (And you also
wind up not worrying about certain sillinesses, like whether power
systems are "analog" or "digital" - since the world no longer has to
be divided up exclusively as one or the other.)
Agreed.

Some people can't seem to wrap their minds around such things, but
then, I'm not really going to worry about that.

There's always a way to misinterpret something, no matter how clearly
it is stated. Besides, I like my illusions, even if they're wrong.

 

[John Smith I]

[stuff]

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

Then wait for analog to make a big comeback? Like the horse and buggy,
err, well, that never did quite make the comeback, did it?

Naaa, someone else can use "risk investment money!"

JS

 

[[email protected]]

On Sat, 7 Jul 2007 14:44:28 -0600, "Bob Myers"

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.

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.

 

[Bob Myers]

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.

 

[Denny]

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

Never bet against new technology...

denny / k8do

 

[John Larkin]

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

 

[Rich the Philosophizer]

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

 

[John Larkin]

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