THE HYPOTHESIS:
Assuming that the equation for the Doppler frequency shift of a source
moving at constant velocity also applies under dynamically changing
velocity conditions, one would expect the propagating sound, that is
produced by a high-frequency source moving dynamically at a low
frequency around a fixed position, to be frequency modulated. One
would further expect that the instantaneous frequency of the
propagating sound would reflect the dynamic low-frequency velocity the
source. If so, the waveform of the fm-demodulated high-frequency
propagating sound, should follow on an instantaneous basis, the
dynamic velocity of the low-frequency velocity of the source.


THE SETUP:
A small circular piezoelectric bimorph, having a resonant frequency of
approximately 10KHz was attached to the 10-lb armature/shaft of a
linear motor. The displacement of the armature/shaft was monitored
by a linear displacement transducer attached to the opposite end of
the armature/shaft. The linear displacement transducer also provided
feedback for the servo amplifier which was driving the linear motor.
Because the linear motor was in a servo loop, the displacement of the
motor followed with reasonable accuracy both sinusoidal and
non-sinusoidal command signals that were applied to the amplifier.
The piezoelectric sound source was driven by a low-distortion
oscillator at 10KHz. The sound emitted by the source was measured by a
microphone at a distance of approximately one foot. The output of the
microphone was amplified, high-pass filtered and applied to a
frequency-to-voltage converter. The output of the
frequency-to-voltage converter was low-pass filtered to reduce the
level of the residual 10KHz carrier, amplified and applied to a signal
averager. The signal averager was triggered by the command signal
that was applied to the linear motor. Averaging was used in order to
remove non-coherent 60Hz that was present in the output of the
demodulator.


THE MOTION OF THE SOUND SOURCE
A triangular command signal having a 50-msec period was applied to the
servo amplifier. A triangular command signal was used in order to
simplify interpretation of the measurement result and to avoid the
phase shift vs time delay ambiguity that would otherwise exist with
fixed frequency sinusoidal excitation. The output of the displacement
transducer was monitored on an oscilloscope and found to be triangular
with rounded corners. The rounding of the corners is due to the
limited closed-bandwidth of the servo. The velocity of the linear
motor was therefore trapezoidal with relatively flat and relatively
long plateaus and relatively short transitions.


THE MEASUREMENT RESULT
The propagating 10KHz signal emitted by the piezo bimorph was applied
to an FFT analyzer in zoom-analysis mode with a resolution bandwidth
of 0.1Hz. When the piezo bimorph was stationary, the propagating
signal picked up by the microphone showed only a single spectral peak
at 10KHz. When the piezo transducer was moving back and forth with a
triangular displacement provided by the linear motor, the propagating
signal received by the microphone contained numerous sidebands which
were indicative of FM modulation. Additionally, the output of the FM
demodulator was observed to be trapezoidal and followed on an
instantaneous basis the velocity of the linear motor and the attached
piezo transducer.


THE CHALLENGE
In science, theory usually follows experimental results. In this case
the experimental result shows that a 10KHz signal applied to a small
piezoelectric source moving back and forth around a fixed position
becomes frequency modulated by the back and forth motion of the
source. The measurement further shows that the received,
FM-demodulated signal follows the instantaneous velocity of the
source. This result is exactly what is expected on the basis of
Doppler frequency shift extrapolated from constant velocity to dynamic
velocity conditions. While some might argue that the observed
FM-like sidebands and the trapezoidal demodulated waveform are the
result of IM distortion, and not Doppler FM, the ball is in their
court. It is now up to them to provide an explanation/analysis
involving an IM producing mechanism in the present experimental setup
that accounts for the present experimental result. Finally, it must
be noted that the purpose of the present measurement was to
demonstrate fundamental phenomenological behavior. The 10KHz carrier
and the 50-msec peridiocity for the displacement of the linear motor
were chosen solely to accommodate the hardware on hand. There is
presently no reason to believe that the outcome of the present
measurement would be different if other carrier frequencies or other
source displacement periodicities or waveshapes were used.

Thank you, Herr Geist.

The Ghost wrote:

THE HYPOTHESIS:
Assuming that the equation for the Doppler frequency shift of a source
moving at constant velocity also applies under dynamically changing
velocity conditions,

And therein is the flaw. Because the driver face is riding
the wave it creates, the distance from the driver to the
detector is not the instantaneous position of its face but
its rest position. That remains constant with a signal that
contains no DC component so that Doppler shift does not occur.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"The Ghost"


THE MOTION OF THE SOUND SOURCE
A triangular command signal having a 50-msec period was applied to the
servo amplifier. A triangular command signal was used in order to
simplify interpretation of the measurement result and to avoid the
phase shift vs time delay ambiguity that would otherwise exist with
fixed frequency sinusoidal excitation.


** Time delay variations and the resultant phase shifts are not removed by
this.


The output of the displacement
transducer was monitored on an oscilloscope and found to be triangular
with rounded corners. The rounding of the corners is due to the
limited closed-bandwidth of the servo. The velocity of the linear
motor was therefore trapezoidal with relatively flat and relatively
long plateaus and relatively short transitions.


** Numbers please - what was the velocity ???

In any case this test is not equivalent to the woofer cone situation since
the piezo is clearly moving *through* the air.




............... Phil

Bob Cain wrote:
And therein is the flaw. Because the driver face is riding the wave it
creates, the distance from the driver to the detector is not the
instantaneous position of its face but its rest position. That remains
constant with a signal that contains no DC component so that Doppler
shift does not occur.

This sounds to me like the 16th century Pope and his dudes refuting
Galileo. Ride-ride-ride the waves!!!!!!!

Ang. C.

On Sun, 15 Aug 2004 11:20:10 +1000, "Phil Allison"
wrote:

[snip]
In any case this test is not equivalent to the woofer cone situation since
the piezo is clearly moving *through* the air.

What's the woofer cone moving through?

But, unless the woofer or piezo is porous, neither would be moving
through the air, nor would air be moving through them.

If the issue is the difference in the local fluid flow field around
the piezo or the woofer cone, how would that affect the Doppler shift?

Ken Plotkin

"Ken Plotkin"
"Phil Allison"

[snip]
In any case this test is not equivalent to the woofer cone situation
since
the piezo is clearly moving *through* the air.

What's the woofer cone moving through?


** It takes a volume of air with it as it pumps - so the same air
molecules remain in contact with the surface ( convection notwithstanding) .


But, unless the woofer or piezo is porous, neither would be moving
through the air, nor would air be moving through them.



** The tiny piezo device is not able to take an air volume with it as it
moves bodily.


If the issue is the difference in the local fluid flow field around
the piezo or the woofer cone, how would that affect the Doppler shift?



** Dunno - but it is interesting to think about since all the familiar
examples of Doppler shift involve the sound source being moved through the
air and exciting it at different places from moment to moment.






.......... Phil

The Ghost wrote:
snip

THE MEASUREMENT RESULT
The propagating 10KHz signal emitted by the piezo bimorph was applied
to an FFT analyzer in zoom-analysis mode with a resolution bandwidth
of 0.1Hz. When the piezo bimorph was stationary, the propagating
signal picked up by the microphone showed only a single spectral peak
at 10KHz. When the piezo transducer was moving back and forth with a
triangular displacement provided by the linear motor, the propagating
signal received by the microphone contained numerous sidebands which
were indicative of FM modulation. Additionally, the output of the FM
demodulator was observed to be trapezoidal and followed on an
instantaneous basis the velocity of the linear motor and the attached
piezo transducer.

snip

Ghost, I think most people here were not doubting that a Doppler-shift will
occurr, but how audible it is. Maybe you can do another experiment: Move the
piezo-frequency down to 1-2kHz to be in a more sensitive area of the ear.
Then use the modulator at a low frequency like 8Hz, where there is another
sensitive area of the ear, and use a high amplitude of 5cm if that is
possible to get the same speed as a woofer at 80Hz with 5mm excursion.
Can you hear the modulation as a small vibrato?
Could you also quantify your transmission index in the form of frequency
deviation vs. mm/s

--
ciao Ban
Bordighera, Italy

"The Ghost" wrote in message
om...

...the propagating
signal received by the microphone contained numerous sidebands which
were indicative of FM modulation.

Redundancy alert!!

You just wrote 'Frequency Modulation modulation'.

OK pedants, fire at will...


'People who can't say what they mean don't mean what they say'


--
'Murphy is my Co-Pilot'

"I won't go into binary counting here. For further information you can
search the Internet, or cut off all but one of your fingers."
-Roger Nichols

Bob Cain wrote:



The Ghost wrote:

THE HYPOTHESIS: Assuming that the equation for the Doppler frequency
shift of a source
moving at constant velocity also applies under dynamically changing
velocity conditions,


And therein is the flaw. Because the driver face is riding the wave it
creates, the distance from the driver to the detector is not the
instantaneous position of its face but its rest position. That remains
constant with a signal that contains no DC component so that Doppler
shift does not occur.

C'mon, Gary. As difficult as I know this will be for you, I
know also that you are smart enough to eventually acknowlede
that I'm correct in my final analysis of this if you are
intellectually honest, which I think you are. I won't crow,
I promise. :-)

Interestingly enough, and probably good for your ego, your's
is really the only acknowledgment I care about.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

In alt.sci.physics.acoustics,rec.audio.pro, "Natalie Drest"
wrote:


"The Ghost" wrote in message
. com...

...the propagating
signal received by the microphone contained numerous sidebands which
were indicative of FM modulation.

Redundancy alert!!

You just wrote 'Frequency Modulation modulation'.

OK pedants, fire at will...

No problem, just don't touch my MIDI interface. And I hang my
pedant on a chain around my neck just like a Real Man...



'People who can't say what they mean don't mean what they say'

-----
http://mindspring.com/~benbradley

On Sun, 15 Aug 2004 14:00:51 +1000, "Phil Allison"
wrote:


** It takes a volume of air with it as it pumps - so the same air
molecules remain in contact with the surface ( convection notwithstanding) .

** The tiny piezo device is not able to take an air volume with it as it
moves bodily.

At what point do the laws of physics that apply to the woofer cone
become different for the piezo?

Phil Allison wrote:
** It takes a volume of air with it as it pumps - so the same air
molecules remain in contact with the surface ( convection notwithstanding) .

If you were willing to ride on the cone (take your cowboy hat with
you), or if you could convince a microphone to be your surrogate, then
indeed no frequency shift as heard by you or the mic would occur. To
that extent you are correct. But we live in a relativistic world whether
you care to or not.

The "observer" or the SLM microphone resides in a stationary reference
frame, while the loudspeaker cone moves with respect to that fixed
reference frame. Whether the air moves by the observer and his/her
microphone, it is still clear that the tone heard will increase in pitch
while the cone is advancing in his/her direction, and reduce in pitch
when receding from said observation location; air still or not. Even if
a steady breeze is blowing in any direction, and the distance is less
that 300 feet, the same FM will occur. Now if there are wind *gusts*,
(accelerations; changes of velocity), then the pitch will change
momentarily... Need we scrutinize any further?

Ang. C.

Ken Plotkin wrote:
On Sun, 15 Aug 2004 14:00:51 +1000, "Phil Allison"
wrote:



** It takes a volume of air with it as it pumps - so the same air
molecules remain in contact with the surface ( convection notwithstanding) .


** The tiny piezo device is not able to take an air volume with it as it
moves bodily.


At what point do the laws of physics that apply to the woofer cone
become different for the piezo?


Perhaps it's related to the efficiency of coupling the LF signal to the
air? At some frequency the air becomes part of the cone's radiating
structure, below that it's not. This would apply the milliHertz vs DC
paradox as well.

On Sun, 15 Aug 2004 12:27:25 -0700, S O'Neill
wrote:

KP At what point do the laws of physics that apply to the woofer cone
KP become different for the piezo?


Perhaps it's related to the efficiency of coupling the LF signal to the
air? At some frequency the air becomes part of the cone's radiating
structure, below that it's not. This would apply the milliHertz vs DC
paradox as well.

Ummm...maybe I should have been ruder in my previous post. The notion
that there is a local flow field for the woofer cone but not one for
the piezo driver is ludicrous. They may be different depending on
size and wavelength, but there will be a local flow for both.

Bob Cain wrote:



The Ghost wrote:

THE HYPOTHESIS: Assuming that the equation for the Doppler frequency
shift of a source
moving at constant velocity also applies under dynamically changing
velocity conditions,


And therein is the flaw. Because the driver face is riding the wave it
creates, the distance from the driver to the detector is not the
instantaneous position of its face but its rest position. That remains
constant with a signal that contains no DC component so that Doppler
shift does not occur.

Another way of saying this is that it is the bulk velocity
at the rest position that propegates as the velocity wave,
with the pressure related in the usual way.

What, then, is the relationship between the surface velocity
of the piston and the bulk velocity of air at the rest
position? If they are proportional, or otherwise related
linearly, then "Doppler distortion" can be relegated to the
dustbin of history. If not, my hat will soon begin eyeing
me warily.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Bob Cain" wrote in message
...

Another way of saying this is that it is the bulk velocity
at the rest position that propegates as the velocity wave,
with the pressure related in the usual way.

Have the terms of discussion changed? I think you originally said that
there cannot be Doppler distortion because the system you were considering
was linear. Gary's experimental setup was linear in the conventional sense
but (of course) produced Doppler distortion. Now it's to do with bulk
velocity.

I don't think it's a good idea to get hung up on definitions of
linearity. Gary's setup produced a form of distortion that you could call
time distortion. This is not a distortion that we usually give a general
name to, although in simple analogue recording systems it is called by
various names depending on the type of speed variation that gives rise to
it. Clearly time distortion will produce frequencies not present in the
original signal, although it is not "non-linear" in the usual sense. I have
to say I can't see why time distortion shouldn't happen in a conventional
speaker setup just as it does in Gary's.

Keep going - I quite enjoy these discussions because it makes me think.

Tony Woolf

Tony wrote:
Have the terms of discussion changed?

No. I believe that they are incomplete.

Consider another mode, called "modulation", which is not, or may not be
considered to be, 'distortion', and more certainly is intended NOT to be
nonlinear. The two simple cases of modulation are amplitude modulation
and frequency modulation. Can anyone here claim these two perturbations
of a steady signal to be nonlinear? We must settle this question first.

I say that the word "distortion" is too pervasive, and is now loosing
its meaning and relevance. For years, I had heard the term 'frequency
distortion' and thought it infer a nonlinear process. Then I learned
that it was being used ion the audio world merely to reflect the fact
that a pass band was not flat. Now we are using it for frequency
modulation via doppler, and sure enough, some other souls are making the
same nonlinear inference, which is also not true.

I think you originally said that
there cannot be Doppler distortion because the system you were considering
was linear. Gary's experimental setup was linear in the conventional sense
but (of course) produced Doppler distortion. Now it's to do with bulk
velocity.

I think this exactly follows my last statements.

I don't think it's a good idea to get hung up on definitions of
linearity.

Right. Non linearity begins when the transfer function (output/input) of
an entity is not a straight line.
Gary's setup produced a form of distortion that you could call
time distortion. This is not a distortion that we usually give a general
name to, although in simple analogue recording systems it is called by
various names depending on the type of speed variation that gives rise to
it. Clearly time distortion will produce frequencies not present in the
original signal, although it is not "non-linear" in the usual sense.

Right. One indictor is that the side bands are in the immediate vicinity
of the primary (carrier) frequencies. No harmonics, for instance.

I have
to say I can't see why time distortion shouldn't happen in a conventional
speaker setup just as it does in Gary's.

'Time distortion' can be inferred from the doppler phenomenon.

Keep going - I quite enjoy these discussions because it makes me
think.

There is a closing line in the stage play
"Teahouse of the August Moon"...

'Pain makes man think,
thought makes man wise,
and wisdom makes life endurable!.'

Ang. C.

'Pain makes man think,
thought makes man wise,
and wisdom makes life endurable!.'

Except, of course, for that unendurable pain!

By the way, those lines are a modified version of something from the Greeks.

Tony wrote:

"Bob Cain" wrote in message
...

Another way of saying this is that it is the bulk velocity
at the rest position that propegates as the velocity wave,
with the pressure related in the usual way.


Have the terms of discussion changed? I think you originally said that
there cannot be Doppler distortion because the system you were considering
was linear.

I did and I do. What in said above is part of the means of
proving that. If it is true and the surface velocity of the
piston is transformed linearly to the bulk velocity at the
rest position then linearity of the system is assured.

Gary's experimental setup was linear in the conventional sense
but (of course) produced Doppler distortion. Now it's to do with bulk
velocity.

In this case experiment that does not confirm theory is not
of particular value, especially when there are other factors
that can contribute to the data. We lack such a theory.

The bulk velocity argument is just another way of getting at
the basic principles involved and one that is getting right
down to acoustics fundamentals.


I don't think it's a good idea to get hung up on definitions of
linearity. Gary's setup produced a form of distortion that you could call
time distortion. This is not a distortion that we usually give a general
name to, although in simple analogue recording systems it is called by
various names depending on the type of speed variation that gives rise to
it. Clearly time distortion will produce frequencies not present in the
original signal, although it is not "non-linear" in the usual sense. I have
to say I can't see why time distortion shouldn't happen in a conventional
speaker setup just as it does in Gary's.

What I hope to see from Gary is a predictive theory with
rigorous math with which his data can be compared. If it
can be done, I'm pretty sure he can do it.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Natalie Drest" wrote in message news:cfn363.

Redundancy alert!!
You just wrote 'Frequency Modulation modulation'.

I trust that your thoughtful insight and technologically salient
contribution to this thread didn't create any permanent damage from
neural overload.

Angelo Campanella wrote:

Tony wrote:

Have the terms of discussion changed?


No. I believe that they are incomplete.

Consider another mode, called "modulation", which is not, or may not be
considered to be, 'distortion', and more certainly is intended NOT to be
nonlinear. The two simple cases of modulation are amplitude modulation
and frequency modulation. Can anyone here claim these two perturbations
of a steady signal to be nonlinear? We must settle this question first.

Angelo, all modulation is performed by non-linear elements.
The test of whether a system is linear or not is whether
there are frequencies in the output that are not in the
input. If there aren't for any input the system is linear.
If there are for any input it isn't linear. This is just
a vernacular statement of the very definition of linearity.

Right. Non linearity begins when the transfer function (output/input) of
an entity is not a straight line.

It's trivial to design a system that has a straight line
transfer function within the limits of measurement if setup
and measurement are done on successive days, or even with
minutes in between, but will distort all to hell if given a
sin wave.

If you have a system that shows a straight line transfer
function regardless of the input, it's not only linear, it
is purely resistive.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Bob Cain wrote:
Angelo, all modulation is performed by non-linear elements. The test of

It's a matter of semantics for modulation and distortion. Non-linear is
a little more specific.

Such arguments often arise between engineers, physicists and
mathematicians; each having a slightly different view of the physical
and virtual worlds. The only hope is that they be specific and to
elaborate while seeking a common language to get the job done.

arividercci, nonlinearity


Ang. C.

"The Ghost" wrote in message
om...
"Natalie Drest" wrote in message
news:cfn363.

Redundancy alert!!
You just wrote 'Frequency Modulation modulation'.

I trust that your thoughtful insight and technologically salient
contribution to this thread didn't create any permanent damage from
neural overload.

Your trust is well placed, though your manners aren't up to much I must say.
You ought to have thanked me- I didn't want you to hand in your dissertation
with silly errors in it.
But hey- go right ahead!

"Angelo Campanella" wrote in message
...

I say that the word "distortion" is too pervasive, and is now loosing
its meaning and relevance. For years, I had heard the term 'frequency
distortion' and thought it infer a nonlinear process. Then I learned
that it was being used ion the audio world merely to reflect the fact
that a pass band was not flat. Now we are using it for frequency
modulation via doppler, and sure enough, some other souls are making the
same nonlinear inference, which is also not true.

As we have found before in this forum, words ("shabby equipment always
deteriorating") have their limitations . When I was trained as a BBC
engineer about 40 years ago, I was told that distortion was anything that
altered the original sound. The BBC Programme Operations Training Manual
(1962) states that distortion occurs when any change in waveform takes place
between two points in a transmission system. It lists (a) phase distortion
i.e., transmission time varying with frequency, (b) a number of types of
non-linear distortion inlcuding what we would now call dynamic range
compression and (c) attenuation or frequency distortion, caused when the
properties of the system vary with frequency. This is slightly different
from my own training which I think used an even more general definition - it
included hum and noise, as well as wow and flutter. I am not trying to say
that this was "correct", I am just saying that you can't t rely on a precise
meaning of such words without further definition.

Tony Woolf

"Tony" wrote in message

"Angelo Campanella" wrote in message
...

I say that the word "distortion" is too pervasive, and is now loosing
its meaning and relevance.

I would say that distortion has always had a broad meaning.

For years, I had heard the term 'frequency
distortion' and thought it infer a nonlinear process. Then I learned
that it was being used in the audio world merely to reflect the fact
that a pass band was not flat.

Yes, this is the well-known linear distortion.

Now we are using it for frequency
modulation via doppler, and sure enough, some other souls are making
the same nonlinear inference, which is also not true.

The definition of distortion given at
http://www.pcavtech.com/techtalk/dist_noise/index.htm is general and
orthodox.

When I was trained as a BBC
engineer about 40 years ago, I was told that distortion was anything
that altered the original sound.

This isn't quite right because noise and interfering signals are quite
different from distortion, but can alter the origional sound.

The BBC Programme Operations
Training Manual (1962) states that distortion occurs when any change
in waveform takes place between two points in a transmission system.

Ignoring noise and interfering signals, this would be about right.

It lists (a) phase distortion i.e., transmission time varying with
frequency, (b) a number of types of non-linear distortion inlcuding
what we would now call dynamic range compression and (c) attenuation
or frequency distortion, caused when the properties of the system
vary with frequency.

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the input
signal but are related to tones in the input signal are called nonlinear
distortion."

This is slightly different from my own training
which I think used an even more general definition - it included hum
and noise, as well as wow and flutter.

Noise can easily and properly be thought of as being distinct from
distortion, but wow and flutter are FM distortion, and agree the formal
definition of nonlinear distortion. However, they are not caused by the
signal acting on itself. They are a result of the action of an interferring
signal, in this case the uneven rotation of a turntable as seen from the
perspective of the stylus.

I am not trying to say that
this was "correct", I am just saying that you can't t rely on a
precise meaning of such words without further definition.

At this time there appears to be pretty good agreement about the formal
definitions of these terms.

"Arny Krueger"

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the input
signal but are related to tones in the input signal are called nonlinear
distortion."



** In what context did you find those words ????

Cyclic frequency variations produced by a tape recorder or TT are not
added tones but mechanically induced errors appearing in the output signal
from a storage system.

Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure transducers.

When you move someone's words from one context to another - that creates
error as well.

Gotta be careful.



............. Phil

"Phil Allison" wrote in message

"Arny Krueger"

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the
input signal but are related to tones in the input signal are called
nonlinear distortion."



** In what context did you find those words ????

Read the parts of the post that you deleted, Phil. Or, see below.

Cyclic frequency variations produced by a tape recorder or TT are not
added tones but mechanically induced errors appearing in the output
signal from a storage system.

The spectrum analyzer shows added tones. The same is true of digital audio
equipment jitter.

Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure
transducers.

Agreed.

When you move someone's words from one context to another - that
creates error as well.

You mean like you just did, Phil? You trashed the context in which the words
were origionally posted, for sure!

BTW, the author of the words above are clearly labelled if you bother to
trace back the provided URL:

"The definition of distortion given at
http://www.pcavtech.com/techtalk/dist_noise/index.htm is general and
orthodox."

Gotta be careful.

Yes you do, Phil.

"Arny Krueger"
"Phil Allison"

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the
input signal but are related to tones in the input signal are called
nonlinear distortion."


** In what context did you find those words ????

Read the parts of the post that you deleted, Phil. Or, see below.


** I see - the context was in fact your own words.

How deceitful to slyly quote yourself the absent expert.



Cyclic frequency variations produced by a tape recorder or TT are not
added tones but mechanically induced errors appearing in the output
signal from a storage system.

The spectrum analyzer shows added tones. The same is true of digital audio
equipment jitter.


** Because that is all the poor dumb animal can do.

BTW A tone is a steady frequency - that is the opposite of what wow
is.



Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure
transducers.

Agreed.


** So wrong to call "non -linear".



When you move someone's words from one context to another - that
creates error as well.

You mean like you just did, Phil?


** Opinion presented as fact.


You trashed the context in which the words were origionally posted, for
sure!


** There was no *context* supplied and still is none in sight.



BTW, the author of the words above are clearly labelled if you bother to
trace back the provided URL:


** Context is not authorship - plus the author seems to be you.



Gotta be careful.

Yes you do, Phil.



** When dealing with a "born again psychopath" - yes.





............. Phil

"Phil Allison" wrote in message

"Arny Krueger"
"Phil Allison"

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the
input signal but are related to tones in the input signal are
called nonlinear distortion."


** In what context did you find those words ????

Read the parts of the post that you deleted, Phil. Or, see below.


** I see - the context was in fact your own words.

How deceitful to slyly quote yourself the absent expert.

Where's the deceit? Is it any kind of a secret around here that PCAVTech is
my web site?

Cyclic frequency variations produced by a tape recorder or TT are
not added tones but mechanically induced errors appearing in the
output signal from a storage system.

The spectrum analyzer shows added tones. The same is true of digital
audio equipment jitter.

** Because that is all the poor dumb animal can do.

Yes, it is bound to tell the truth.

BTW A tone is a steady frequency - that is the opposite of what wow
is.

Doooh!

Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure
transducers.

Agreed.

** So wrong to call "non -linear".

In a sense, I agree.

When you move someone's words from one context to another - that
creates error as well.

You mean like you just did, Phil?

** Opinion presented as fact.

Phil, your heavy-handed editing is a matter of fact, easily found in the
google archive of RAP.

You trashed the context in which the words were origionally posted,
for sure!

** There was no *context* supplied and still is none in sight.

Say what?

BTW, the author of the words above are clearly labelled if you
bother to trace back the provided URL:

** Context is not authorship - plus the author seems to be you.

Is it any kind of a secret around here that PCAVTech is my web site?

Gotta be careful.

Yes you do, Phil.

** When dealing with a "born again psychopath" - yes.

Yawn.

Tony wrote:
This is slightly different
from my own training which I think used an even more general definition - it
included hum and noise, as well as wow and flutter. I am not trying to say
that this was "correct", I am just saying that you can't t rely on a precise
meaning of such words without further definition.

Sadly, the working definition that I see most often is that "distortion"
is the same thing as "clipping.". And that DRIVES ME UP THE FREAKING WALL.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Phil Allison wrote:

Cyclic frequency variations produced by a tape recorder or TT are not
added tones but mechanically induced errors appearing in the output signal
from a storage system.

Actually, the sidebands that result from those mechanically-induced errors
are added tones. In typical systems, they are so low displacement that it
is not all that singificant.

Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure transducers.

Agreed.

BUT, both the case of flutter and the case of doppler modulation are both
examples of FM modulation of the signal; what makes them substantively
different is where the modulating signal is coming from.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Arny Krueger"
"Phil Allison"

Nonlinear distortion has a very clear and distinct definition:

"Errors that add tones to the output signal that not present in the
input signal but are related to tones in the input signal are
called nonlinear distortion."


** In what context did you find those words ????

Read the parts of the post that you deleted, Phil. Or, see below.


** I see - the context was in fact your own words.

How deceitful to slyly quote yourself the absent expert.

Where's the deceit?


** How deceitful to *slyly quote yourself* as the absent expert.

How ***dishonest*** to USE your own definition as a quote.

WHAT an EGOMANIAC !!!!!!!!!!!!!!!!



Cyclic frequency variations produced by a tape recorder or TT are
not added tones but mechanically induced errors appearing in the
output signal from a storage system.

The spectrum analyzer shows added tones. The same is true of digital
audio equipment jitter.

** Because that is all the poor dumb animal can do.

Yes, it is bound to tell the truth.


** Not like you then - Arny.



BTW A tone is a steady frequency - that is the opposite of what
wow
is.

Doooh!


** Non answer to a crucial point noted.

More blatant dishonesty noted too.



Phase modulation of a high frequency by a low one and it associated
Doppler shift are errors inherent in air displacement pressure
transducers.

Agreed.

** So wrong to call "non -linear".

In a sense, I agree.


** Complete the reverse from previous stance here.

More blatant dishonesty.



When you move someone's words from one context to another - that
creates error as well.

You mean like you just did, Phil?


** Opinion presented as fact.



Phil, your heavy-handed editing is a matter of fact, easily found in the
google archives\.


** More opinion presented as fact.

No lie is beneath this asshole.



You trashed the context in which the words were origionally posted,
for sure!

** There was no *context* supplied and still is none in sight.

Say what?


** More opinion presented as fact.

No lie is beneath this asshole.



BTW, the author of the words above are clearly labelled if you
bother to trace back the provided URL:

** Context is not authorship - plus the author seems to be you.

Is it any kind of a secret around here that PCAVTech is my web site?


** Still no context is in sight.

( Does Anry even know what the term "context" means ??? )


Gotta be careful.

Yes you do, Phil.

** When dealing with a "born again psychopath" - yes.

Yawn.


** NO lie is beneath this "born again psychopath".




.............. Phil

Frequency and phase response errors are a form of linear distortion
and in audio work is not generally called "distortion" because no new
frequencies are created.

Frequency Modulation (like that caused by wow and flutter or clock
jitter or Doppler) is a non-linear process and produces new tones
(sidebands) (look up Bessel if you don't belive this) and in this
audio context therefore is a form of non-linear distortion because new
frequencies are created.

In fact the point I was making is that the sidebands produced by
Doppler are identical to those that would be produced by actual
intermodulation distortion and thefore Doppler and IM should sound the
same and I see no problem therefore calling Doppler a form of
distortion.



Mark

"Mark" wrote in message
om
Frequency and phase response errors are a form of linear distortion
and in audio work is not generally called "distortion" because no new
frequencies are created.

Frequency Modulation (like that caused by wow and flutter or clock
jitter or Doppler) is a non-linear process and produces new tones
(sidebands) (look up Bessel if you don't belive this) and in this
audio context therefore is a form of non-linear distortion because new
frequencies are created.

In fact the point I was making is that the sidebands produced by
Doppler are identical to those that would be produced by actual
intermodulation distortion and thefore Doppler and IM should sound the
same and I see no problem therefore calling Doppler a form of
distortion.

Simply not true.

Common IM is AM distortion, which as several have pointed out produces
sidebands that have equal amplitude and phase.

Doppler, flutter, wowo and clock jitter are FM distortion produce sidebands
differ in terms of phase.

Common IM is AM distortion, which as several have pointed out produces
sidebands that have equal amplitude and phase.

Doppler, flutter, wowo and clock jitter are FM distortion produce sidebands
differ in terms of phase.

That "wowo" will really get ya. It got its name when people heard it and said
"Wo-wo! That sounds awful!"

The only difference between AM and weak FM is the phase of the sidebands.

"Mark"

Frequency and phase response errors are a form of linear distortion
and in audio work is not generally called "distortion" because no new
frequencies are created.

** Fine.

Frequency Modulation (like that caused by wow and flutter or clock
jitter or Doppler) is a non-linear process ....


** Speed variations in the playback of a mechanical storage device are a
linear process.

The output signal contains errors from what is desired - so that is a
"distortion".


and produces new tones (sidebands)


** A tone infected with wow is not a new tone - it is simply FM of the
old one.


(look up Bessel if you don't belive this) and in this
audio context therefore is a form of non-linear distortion because new
frequencies are created.


** Categorise it under the heading "non-linear" if you like, but the
process that creates it is a linear one.


In fact the point I was making is that the sidebands produced by
Doppler are identical to those that would be produced by actual
intermodulation distortion....


** Not identical - the maths shows they are quite different.


and thefore Doppler and IM should sound the
same


** No way - never heard a Leslie speaker cabinet in action ???

Now that has audible Doppler shift and it DONT sound like AM one bit.



and I see no problem therefore calling Doppler a form of
distortion.


** You have come full circle and are now biting your own tail.




............ Phil

"Natalie Drest" wrote in message ...

Your trust is well placed, though your manners aren't up to much I must say.
You ought to have thanked me- I didn't want you to hand in your dissertation
with silly errors in it.
But hey- go right ahead!


I regret having missed your coronation as queen identifier of silly
errors in newsgroup posts. You obviously have a great challenge
ahead of you because most if not all newsgroup posts contain silly
errors of one sort or another. However, unlike you, most readers
focus on substance and ignore those silly errors. If you expect to be
thanked for your input, perhaps you should do the same. Lastly, if
you want to identfy a really silly error, take a look into a mirror.

"Phil Allison" wrote in message

"Mark"

Frequency and phase response errors are a form of linear distortion
and in audio work is not generally called "distortion" because no new
frequencies are created.

** Fine.

Frequency Modulation (like that caused by wow and flutter or clock
jitter or Doppler) is a non-linear process ....


** Speed variations in the playback of a mechanical storage device
are a linear process.

The output signal contains errors from what is desired - so that
is a "distortion".


and produces new tones (sidebands)


** A tone infected with wow is not a new tone - it is simply FM of
the old one.

Right, but FM causes sidebands.

(look up Bessel if you don't belive this) and in this
audio context therefore is a form of non-linear distortion because
new frequencies are created.

Those Bessel functions predict the amplitude of the sidebands, right?

Sidebands around a carrier tone are in fact new tones. If you get the
modulation index up high enough, you can even hear them as separate tones.

** Categorise it under the heading "non-linear" if you like, but the
process that creates it is a linear one.

I wouldn't focus on that linear part, too confusing for newbies. Instead,
say something like "It's not dependent on parameter variation due to the
input signal".

In fact the point I was making is that the sidebands produced by
Doppler are identical to those that would be produced by actual
intermodulation distortion....

** Not identical - the maths shows they are quite different.

Agreed, the phase differs.

and thefore Doppler and IM should sound the
same

** No way - never heard a Leslie speaker cabinet in action ???

A way too compex example to draw any conclusions from.

Now that has audible Doppler shift and it DONT sound like AM one bit.

I'll agree with this.

I did the following experiment:

(1) Create 4 KHz tone peak amplitude -1 dB AM with 50 Hz producing sidebands
@-29 dB

(2) Create 4 KHz tone peak amplitude -1 dB FM with 50 Hz producing sidebands
@-29 dB

No comparison. The FM-modulated tone sounded essentially unmodulated, but
the AM-modulated tone sounded clearly modulated.


and I see no problem therefore calling Doppler a form of
distortion.


** You have come full circle and are now biting your own tail.

Agreed - Doppler distorition is a form of nonlinear distortion.

Doppler differs from other common forms of FM distortion in audio such as
wow, flutter, and jitter; becuase modulating signal is part of the origional
signal. With wow, flutter, and jitter the modulating signal may or may not
be part of the origional signal. With wow and flutter the modulating signal
is usually not part of the origional signal. However, there is a form of FM
distortion in vinyl where the modulating signal is part of the origional
signal. It is geometrically-based and is due to the use of offset tone arms.

"Arny Krueger"
"Phil Allison"
"Mark"


Frequency Modulation (like that caused by wow and flutter or clock
jitter or Doppler) is a non-linear process ....


** Speed variations in the playback of a mechanical storage device
are a linear process.

The output signal contains errors from what is desired - so that
is a "distortion".


and produces new tones (sidebands)


** A tone infected with wow is not a new tone - it is simply FM of
the old one.

Right, but FM causes sidebands.


** Circular thinking.


** Categorise it under the heading "non-linear" if you like, but the
process that creates it is a linear one.

I wouldn't focus on that linear part, too confusing for newbies.


** Not near as confusing as all the other tripe posted here.



In fact the point I was making is that the sidebands produced by
Doppler are identical to those that would be produced by actual
intermodulation distortion....

** Not identical - the maths shows they are quite different.

Agreed, the phase differs.


** And the frequency spectrum. AM of a frequency produces only two new
frequencies ( sum and diff ) - while FM produces a *whole bunch*.



I did the following experiment:

(1) Create 4 KHz tone peak amplitude -1 dB AM with 50 Hz producing
sidebands
@-29 dB

(2) Create 4 KHz tone peak amplitude -1 dB FM with 50 Hz producing
sidebands
@-29 dB

No comparison. The FM-modulated tone sounded essentially unmodulated, but
the AM-modulated tone sounded clearly modulated.



** The ear's sensitivity phase modulation at an audio frequency is clearly
quite poor.





............ Phil