Revisiting the Power Explanation
 

Cecil Moore wrote:

Keith Dysart wrote:

And just for greater certainty, I forgot to mention that the
reflection coefficient from the line to the generator is 0 in
my experiment (generator impedance is equal to the line
characteristic impedance) so using the reflection coefficient,
there are no reflections.

Because it is an active source, not a passive resistor,
your reflection coefficient is wrong.

He will completely ignore this and keep insisting on his truth. Me
thinks he is trolling......

Revisiting the Power Explanation
 

Cecil Moore wrote in
et:

Owen Duffy wrote:
Cecil Moore wrote in news:ZbBOh.19326$uo3.18213
@newssvr14.news.prodigy.net:

Remember, the magnitude of energy in a transmission line
is *EXACTLY* the amount of energy needed to support
the forward joules/sec and the reflected joules/sec.

If you go beyond your (unqualified) average view of the world and
drilled down on the fields in the line as a function of time and
position, and their relationship with steady state real and reactive
energy flow at each end of the line in the general case, it may
provide you with a more correct view of the tranmission line and its
load and source in your favoured energy context.

I have done that, Owen, and let's see if your experience is
different from mine. Please go to the following Florida State
University web page:

http://micro.magnet.fsu.edu/primer/j...terference/wav
einteractions/index.html

Cecil, I am talking about the way in the steady state in which energy is
stored in E and H fields within the transmission line when standing waves
exist, and the way in which energy is exchanged between E and H fields
within the line, and the load and the source at each end of the line, and
the net energy flow averaged over time (power).

Your analysis of energy waves or power waves doesn't give you the
information to see that level of detail.

Owen

Revisiting the Power Explanation
 

On Mar 28, 10:20 pm, Cecil Moore wrote:
Keith Dysart wrote:
Can you demonstrate that without changing the configuration of
the experiment? Only then will your demonstration be convincing.

Anyone can demonstrate that by setting it up on the bench.
Guaranteed, you would see ghosting where you deny they exist.

So you find no flaws in my analysis but insist that the results
are incorrect. Hhhmmmmm.

And just for greater certainty, I forgot to mention that the
reflection coefficient from the line to the generator is 0 in
my experiment (generator impedance is equal to the line
characteristic impedance) so using the reflection coefficient,
there are no reflections.

Because it is an active source, not a passive resistor,
your reflection coefficient is wrong.

May I suggest that you check any reference on the subject of
reflection coefficient. In none of them will you find the
definition to have anything other than two impedances.

So as I said, things are not the same. And ghosts are a
transient phenomenom.

OTOH, because of noise, steady-state cannot exist
in reality so fixed ghosting is as close to steady-
state as we are going to get.

Sorry. No ghosts in my example.

For practical examples, you could consider any reference that
discusses driving digital signals down a transmission line.
One of the options for preventing reflections (which can
really mess up the reception of the signal), is matching
at the source. Others include matching at the load end.
The pros and cons of the various options will be discussed.

Please find errors without changing the experiment.

I did. Your simple-minded reflection coefficient is bogus.

Reflection coefficient is actually quite simple.

RC = (Z2-Z1)/(Z2+Z1)

I challenge you to find any reference with a different definition.

But to explore your contention that RC is different when there
is an active source, could you kindly provide the expression
describing RC in such a situation.

It occurs to me that you may not be aware how to compute the
impedance of circuit with active sources. Its quite simple.
Replace the voltage sources with shorts and the current sources
with opens. Then using the rules for parallel and series
impedances, compute the result. Use this in the expression
for RC.

May I suggest again that obtaining a different result with a
different experiment is not a surprise.

The two experiments are only different in your mind, not
in reality. The results of both experiments are the same
and you can prove it to yourself on the bench.

Well, then just use my experiment so that we do not have to
argue about whether they are the same.

When you compute the quantity of the re-reflection that
my experiment generates, I will be convinced. But do not
be surprised that I am not convinced when you compute the
reflections for a different experiment.

....Keith

Revisiting the Power Explanation
 

On Mar 28, 11:40 pm, Dan Bloomquist wrote:
Cecil Moore wrote:
Keith Dysart wrote:

And just for greater certainty, I forgot to mention that the
reflection coefficient from the line to the generator is 0 in
my experiment (generator impedance is equal to the line
characteristic impedance) so using the reflection coefficient,
there are no reflections.

Because it is an active source, not a passive resistor,
your reflection coefficient is wrong.

He will completely ignore this and keep insisting on his truth. Me
thinks he is trolling......

Good day Dan,

I offer you the same challenge as Cecil, find the error in my
analysis and then compute the correct amount of re-reflection.

And provide the expression for computing RC in the presence of
sources if it is different than the conventional
RC=(Z2-Z1)/(Z2+Z1).

When you find nothing wrong with the analysis, ask yourself why
you don't believe the results?

....Keith

Revisiting the Power Explanation
 

Dan Bloomquist wrote:
He will completely ignore this and keep insisting on his truth. Me
thinks he is trolling......

Please don't discourage innovation. He can patent his
ten cent method of eliminating reflections and obsolete
the circulator market. Maybe someone should warn
Tektronix.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Owen Duffy wrote:
Your analysis of energy waves or power waves doesn't give you the
information to see that level of detail.

Whatever level of detail one chooses, the energy
in the forward waves plus the energy in the reflected
waves will equal the total energy in the transmission
line which will always be the energy sourced and not
delivered to the load (in a lossless system). This
will be true right down to the last photon.

Unless someone can prove that EM energy is
transformed into some other form of energy for
storage in the transmission line and then transformed
back to EM energy when the transmission line is
emptied, the nature of EM energy and the conservation
of energy principle dictate what happens. EM (photonic)
wave energy cannot move at less than the speed of
light (modified by VF).
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

On Mar 29, 7:00 am, "Keith Dysart" wrote:
Good day Dan,

I offer you the same challenge as Cecil, find the error in my
analysis and then compute the correct amount of re-reflection.

Since it can be quite difficult to locate errors in analysises,
I'll offer a simpler challenge to you and Cecil.

For the example I proposed, using the approach of your choice,
compute the magnitude of the first re-reflected signal to reach
the load.

Recall the line is 31 wavelengths long so the signal reaches
the load 31 cycles after the generator is turned on. There is
a reflection which reaches the generator 31 cycles later and
any re-reflection will reach the load after a further 31 cycles.

So you need to compute the magnitude of the reflection which
reaches the load after 93 cycles. This would be the first ghost.

You need to show your work. Handwaving -25dB will not be considered
as answering the question.

....Keith

PS. If you prefer, you may use a slightly different example for
which computation may be easier:
- the line is 1 second long
- the generator creates a 450 V step function at time 0
What is the magnitude of the re-reflection that reaches the load
after 3 seconds?

PPS. The answer to the two problems will be the same.

Revisiting the Power Explanation
 

Keith Dysart wrote:
So you find no flaws in my analysis but insist that the results
are incorrect. Hhhmmmmm.

The flaws have been pointed out and you have ignored them.
THE REFLECTED WAVE DOES NOT SEE Rs=450 OHMS IF THE SOURCE
IS TURNED ON. THE REFLECTED WAVE DOES NOT EXIST IF THE
SOURCE IS TURNED OFF. Take a look at:

http://www.w2du.com/r3ch19a.pdf

Sorry. No ghosts in my example.

Correction: No ghosts in your wet dream. I suggest that you
patent your ten cent solution to eliminate reflections and
sell the patent to Tektronix since you have obviously rendered
all those expensive circulators in the world obsolete. And why
would anyone go to the trouble of installing a 20 dB pad when,
according to you, a single ten cent resistor will perform better?

Reflection coefficient is actually quite simple.
RC = (Z2-Z1)/(Z2+Z1)
I challenge you to find any reference with a different definition.

Sorry, all my references are at my new QTH but here are
a few from memory:

rho = SQRT(Pref/Pfor) = Vref/Vfor = Iref/Ifor = (SWR-1)/(SWR+1)

One of the options for preventing reflections (which can
really mess up the reception of the signal), is matching
at the source.

Yes of course, one can do that with a circulator or pad. One
cannot accomplish "matching at the source" with a ten cent
resistor. Such an assertion is sophomoric.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Keith Dysart wrote:
I offer you the same challenge as Cecil, find the error in my
analysis and then compute the correct amount of re-reflection.

We will be glad to do that if you will provide the
impedance value encountered by the reflected wave
with the source turned on. You have not yet done that.
Hint: It doesn't matter what impedance the reflected
wave encounters with the source turned off since
reflected waves are non-existent during that
condition.
--
73, Cecil http://www.w5dxp.com

Revisiting the Power Explanation
 

Keith Dysart wrote:
So you need to compute the magnitude of the reflection which
reaches the load after 93 cycles. This would be the first ghost.

We cannot do that until you furnish more information about
the source. A math model would be nice.
--
73, Cecil, w5dxp.com