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"Goofball_star_dot_etal" wrote in message

On Sun, 23 Nov 2003 15:30:04 -0500, "Arny Krueger"
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"ScottW" wrote in message
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"Erik Squires" wrote in
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So, here's my question. If I digitize a 15 kHz signal, using a
44.1 kHz sampling rate, I'm going to get about 3 samples /
cycle.

Are the normal digital filters good enough to reproduce a 15
kHz signal with varying amplitude?

Deconstruct this signal to frequency domain and it won't be a
pure 15 kHz.

Wrong.

What is the frequency of the amplitude "variation"?

Obviously, 15 KHz.

Show me the Fourier series which contains only 15 kHz components
which results in a 15Khz waveform with "varying amplitude".


A 15 KHz wave itself has varying amplitude. The amplitude varies at
a rate of 15 KHz.

You talk instantaneous values, him talk envelope. Waste time.

That's his choice. If he wants a specific answer he should ask a specific
question.

Look at the original post.
Your context is wrong.
Too bad you gave the original poster such erroneous input.

ScottW

"ScottW" wrote in message
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"Arny Krueger" wrote in message
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"Goofball_star_dot_etal" wrote in message

On Sun, 23 Nov 2003 15:30:04 -0500, "Arny Krueger"
wrote:

"ScottW" wrote in message
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"Arny Krueger" wrote in message
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"Erik Squires" wrote in
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So, here's my question. If I digitize a 15 kHz signal,
using a
44.1 kHz sampling rate, I'm going to get about 3 samples /
cycle.

Are the normal digital filters good enough to reproduce a 15
kHz signal with varying amplitude?

Deconstruct this signal to frequency domain and it won't be a
pure 15 kHz.

Wrong.

What is the frequency of the amplitude "variation"?

Obviously, 15 KHz.

Show me the Fourier series which contains only 15 kHz components
which results in a 15Khz waveform with "varying amplitude".


A 15 KHz wave itself has varying amplitude. The amplitude varies at
a rate of 15 KHz.

You talk instantaneous values, him talk envelope. Waste time.

That's his choice. If he wants a specific answer he should ask a
specific question.

Look at the original post.

I did.

Your context is wrong.

Wrong, the context wasn't set by me/ The problemis your comment is vague.

Too bad you gave the original poster such erroneous input.

Too bad you can't take responsibility for your own actions.

"Arny Krueger" wrote in message
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"ScottW" wrote in message
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"Goofball_star_dot_etal" wrote in message

On Sun, 23 Nov 2003 15:30:04 -0500, "Arny Krueger"
wrote:

"ScottW" wrote in message
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"Erik Squires" wrote in
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So, here's my question. If I digitize a 15 kHz signal,
using a
44.1 kHz sampling rate, I'm going to get about 3 samples /
cycle.

Are the normal digital filters good enough to reproduce a 15
kHz signal with varying amplitude?

Deconstruct this signal to frequency domain and it won't be a
pure 15 kHz.

Wrong.

What is the frequency of the amplitude "variation"?

Obviously, 15 KHz.

Show me the Fourier series which contains only 15 kHz components
which results in a 15Khz waveform with "varying amplitude".


A 15 KHz wave itself has varying amplitude. The amplitude varies at
a rate of 15 KHz.

You talk instantaneous values, him talk envelope. Waste time.

That's his choice. If he wants a specific answer he should ask a
specific question.

Look at the original post.

I did.

Your context is wrong.

Wrong, the context wasn't set by me/ The problemis your comment is vague.

BS, the context was set by the original poster when he specified a
signal with varying amplitude which has obvious implications.

Too bad you gave the original poster such erroneous input.

Too bad you can't take responsibility for your own actions.


Look at this paragraph dimwit and explain how your bs response
about instantaneous signal levels deals with "varying amplitude".

"Are the normal digital filters good enough to reproduce a 15 kHz singal
with
varying amplitude? "

You are wrong, again.

ScottW

"ScottW" wrote in message
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Look at this paragraph dimwit and explain how your bs response
about instantaneous signal levels deals with "varying amplitude".

"Are the normal digital filters good enough to reproduce a 15 kHz
signal with varying amplitude? "

Since I now know Scotty that in your limited, fumbling way, you were trying
to describe a 15 KHz tone that is modulated, I can say quite clearly:

The answer is: Normal digital filters are plenty good enough to reproduce a
15 kHz signal with a varying amplitude of the kind actually seen with
music. For example if that 15 KHz signal is amplitude modulated with say 1
KHz, then there are sidebands at 14 KHz and 16 KHz. There's no problem
passing both the carrier at 15 KHz and the sidebands through a normal 44.1
KHz reconstruction filter which has a brick wall characteristic at 22.05 KHz

Notice that the proper way to ask the question involves the word
"modulated", or something like it.

If you wanted to make up a situation where normal 44.1 KHz reconstruction
filters significantly inhibit reproduction of a modulated tone, you'd pick a
much higher carrier frequency, such as 21.50 KHz, not 15 KHz.

My earlier answer:

"Three samples is sufficient to define a sine wave that has unique
frequency,
phase and amplitude. In fact, just slightly more than two samples is
sufficient." still applies.

In the case of the 15 KHz sine wave modulated with 1 KHz, 44.1 KHz sampling
is adequate to handle the highest frequency that one finds in the Fourier
analysis of the signal, which is 16 KHz.

"Arny Krueger" wrote in message
...
"ScottW" wrote in message
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Look at this paragraph dimwit and explain how your bs response
about instantaneous signal levels deals with "varying amplitude".

"Are the normal digital filters good enough to reproduce a 15 kHz
signal with varying amplitude? "

Since I now know Scotty that in your limited, fumbling way, you were
trying
to describe a 15 KHz tone that is modulated, I can say quite clearly:

The answer is: Normal digital filters are plenty good enough to reproduce
a
15 kHz signal with a varying amplitude of the kind actually seen with
music. For example if that 15 KHz signal is amplitude modulated with say
1
KHz, then there are sidebands at 14 KHz and 16 KHz. There's no problem
passing both the carrier at 15 KHz and the sidebands through a normal
44.1
KHz reconstruction filter which has a brick wall characteristic at 22.05
KHz


Thanks for admitting I was correct in my original post where I said:
"Deconstruct this signal to frequency domain and it won't be a pure
15 kHz."

To which you replied in error:
"Wrong."



Notice that the proper way to ask the question involves the word
"modulated", or something like it.

Then go bitch at the original poster. I don't know what you find so
complicated and incomprehensible about "varying amplitude"
but it really isn't. Maybe your general engineering cirriculum
wasn't all that comprehensive.

If you wanted to make up a situation where normal 44.1 KHz reconstruction
filters significantly inhibit reproduction of a modulated tone, you'd
pick a
much higher carrier frequency, such as 21.50 KHz, not 15 KHz.

My earlier answer:

"Three samples is sufficient to define a sine wave that has unique
frequency,
phase and amplitude. In fact, just slightly more than two samples is
sufficient." still applies.

In the case of the 15 KHz sine wave modulated with 1 KHz, 44.1 KHz
sampling
is adequate to handle the highest frequency that one finds in the Fourier
analysis of the signal, which is 16 KHz.

None of which changes the relevance of my original response to which you
replied in
error. Thank you for finally admitting the truth.

ScottW

"ScottW" wrote in message
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"Arny Krueger" wrote in message
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"ScottW" wrote in message
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Look at this paragraph dimwit and explain how your bs response
about instantaneous signal levels deals with "varying amplitude".

"Are the normal digital filters good enough to reproduce a 15 kHz
signal with varying amplitude? "

Since I now know Scotty that in your limited, fumbling way, you were
trying
to describe a 15 KHz tone that is modulated, I can say quite clearly:

The answer is: Normal digital filters are plenty good enough to
reproduce a
15 kHz signal with a varying amplitude of the kind actually seen with
music. For example if that 15 KHz signal is amplitude modulated with say
1
KHz, then there are sidebands at 14 KHz and 16 KHz. There's no problem
passing both the carrier at 15 KHz and the sidebands through a normal
44.1
KHz reconstruction filter which has a brick wall characteristic at 22.05
KHz

Thanks for admitting I was correct in my original post where I said:
"Deconstruct this signal to frequency domain and it won't be a pure
15 kHz."

Unfortunately, you didn't say that at the time.

To which you replied in error:
"Wrong."

Regrettably, we were talking about pure tones at the time.

Notice that the proper way to ask the question involves the word
"modulated", or something like it.

Then go bitch at the original poster.

He was clearly talking about a pure tone.

I don't know what you find so
complicated and incomprehensible about "varying amplitude"
but it really isn't.

Varying amplitude can clearly mean a number of things, and in the context of
digitizing it meant the fact that the values of the samples vary.

Maybe your general engineering curriculum wasn't all that comprehensive.

Obviously Scotty, whatever engineering education you have, you weren't
prepared to discuss your thoughts with any useful degree of clarity.

If you wanted to make up a situation where normal 44.1 KHz
reconstruction
filters significantly inhibit reproduction of a modulated tone, you'd
pick a
much higher carrier frequency, such as 21.50 KHz, not 15 KHz.

My earlier answer:

"Three samples is sufficient to define a sine wave that has unique
frequency,
phase and amplitude. In fact, just slightly more than two samples is
sufficient." still applies.

In the case of the 15 KHz sine wave modulated with 1 KHz, 44.1 KHz
sampling
is adequate to handle the highest frequency that one finds in the
Fourier
analysis of the signal, which is 16 KHz.

None of which changes the relevance of my original response to which you
replied in error.


There was no error on my part Scotty. You made a vague comment and then
redefined it after the fact in a lame attempt to make what you said seem
sensible.

Thank you for finally admitting the truth.

The truth is Scotty that I made no errors, told no lies. I notice that you
have zero appreciation for the fact that I worked extra hard to show where
you went wrong.

Arny Krueger wrote:

The truth is Scotty that I made no errors, told no lies. I notice that you
have zero appreciation for the fact that I worked extra hard to show where
you went wrong.

Hi, Arny and Scott! It's been a while...

I took the time to follow this thread back to the beginning, and
it's pretty clear that you've gone from arguing about the
question originally posed to arguing about who misinterpreted
what and whose fault it is that things have gotten so murky and
convoluted.

In some of my (admittedly few) RAO debates, I've wished for
somebody to jump into the fray, declare a winner, and put the
discussion out of its misery. I suppose you've got to give before
you get, so in the giving spirit I offer the following:

Here is the salient part of the original query. And please -- no
accusations of selective editing. It really *is* the salient part
of the question.

--------------------

Are the normal digital filters good enough to reproduce a 15 kHz
singal with
varying amplitude? How accurate is that signal, is there no lag
in the
reconstructed signal? I mean, if the amplitude of the original
changes, is
the reconstructed signal as true at 15 kHz as at 4 kHz?

--------------------

It seems pretty clear to me that the poster was talking about a
time-varying envelope, even though the word "envelope" never
appears. Granted, it could have been worded better. But I think
that's how anybody who works with this stuff would interpret the
query.

I declare Scott the winner.

Glenn Z

Scott:

To clarify, when I said 15 kHz wave of varying amplitude, I did not mean a
signal who's instantaneous amplitude was varying between fixed maximum and
minimum at 15kHz.

I meant, a 15 kHz signal who's peak to peak amplitude is decaying. Say, if
I had a 15 kHz signal from a generator, and I was slowly turning the gain up
or down.

This is the same, I would imagine, as a string or bell after it's been
struck (plucked). Can 3 points on this sine wave really accurately convey
this natural decay?

Thanks!


Erik


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news "Goofball_star_dot_etal" wrote in message

On Sun, 23 Nov 2003 15:30:04 -0500, "Arny Krueger"
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"Erik Squires" wrote in
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ervers.com...

So, here's my question. If I digitize a 15 kHz signal,
using a
44.1 kHz sampling rate, I'm going to get about 3 samples /
cycle.

Are the normal digital filters good enough to reproduce a 15
kHz signal with varying amplitude?

Deconstruct this signal to frequency domain and it won't be a
pure 15 kHz.

Wrong.

What is the frequency of the amplitude "variation"?

Obviously, 15 KHz.

Show me the Fourier series which contains only 15 kHz components
which results in a 15Khz waveform with "varying amplitude".


A 15 KHz wave itself has varying amplitude. The amplitude varies at
a rate of 15 KHz.

You talk instantaneous values, him talk envelope. Waste time.

That's his choice. If he wants a specific answer he should ask a
specific question.

Look at the original post.

I did.

Your context is wrong.

Wrong, the context wasn't set by me/ The problemis your comment is
vague.

BS, the context was set by the original poster when he specified a
signal with varying amplitude which has obvious implications.

Too bad you gave the original poster such erroneous input.

Too bad you can't take responsibility for your own actions.


Look at this paragraph dimwit and explain how your bs response
about instantaneous signal levels deals with "varying amplitude".

"Are the normal digital filters good enough to reproduce a 15 kHz singal
with
varying amplitude? "

You are wrong, again.

ScottW

Erik Squires wrote:
Scott:

To clarify, when I said 15 kHz wave of varying amplitude, I did not mean a
signal who's instantaneous amplitude was varying between fixed maximum and
minimum at 15kHz.

I meant, a 15 kHz signal who's peak to peak amplitude is decaying. Say, if
I had a 15 kHz signal from a generator, and I was slowly turning the gain up
or down.

This is how Scott interpreted your question and it's also how most
intelligent people would interpret your question.

This is the same, I would imagine, as a string or bell after it's been
struck (plucked). Can 3 points on this sine wave really accurately convey
this natural decay?

Audibly? Yes. The modulation will create frequency content beyond the
original 15 kHz -- how far beyond is a function of the modulation. But
as long as you're sampling at a rate greater than twice the modulated
waveform's highest frequency (and using an antialiasing filter pre-A/D),
it'll work.

Remember, it's not just "three points on a sine wave." You're sampling
throughout the duration of the waveform, tracking the envelope as it
evolves.

Glenn Z

"Erik Squires" wrote in message
ervers.com...
Scott:

To clarify, when I said 15 kHz wave of varying amplitude, I did not mean
a
signal who's instantaneous amplitude was varying between fixed maximum
and
minimum at 15kHz.

I meant, a 15 kHz signal who's peak to peak amplitude is decaying. Say,
if
I had a 15 kHz signal from a generator, and I was slowly turning the gain
up
or down.

If you're turning the gain up and down at some rate (frequency), that will
be part of the signal and will give it a frequency content other than
the 15 kHz you stated. That is the extent
of my comment.


This is the same, I would imagine, as a string or bell after it's been
struck (plucked). Can 3 points on this sine wave really accurately
convey
this natural decay?

Within audible limits. I suspect there is more error in the initial attack
(pluck) then in the decay.

ScottW