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Old 2nd September 2009, 11:48 PM   #891
brianco is offline brianco  Ireland
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Default John curl....

....PLeased that your eye is back on target and that you can still shoot from the hip.
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Old 3rd September 2009, 12:59 PM   #892
syn08 is offline syn08  Canada
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Quote:
Originally Posted by john curl View Post
The extra distortion products appear to follow a low order Bessel function, which is superimposed on the normal IM byproducts. Anyone out there have enough knowledge to contribute to this discussion?
Yes, but I'm afraid it would be useless. Nobody ever won an argument against you, and unfortunately not because you are always right, but because you won't ever admit you are wrong.

Anyway, there's nothing to prove or further investigate in your statement. Each PM or FM signal expands as an infinite sum of products between the Bessel functions of i-th order and the i-th order sidebands. Also obviously, as long as the PM or FM modulation is "small", high order products can always be safely neglected, so only low order Bessel functions matter.

So essentially your statement is empty of any meaning, beyond basic engineering knowledge. You failed again in adding any argument to your extraordinary claims regarding PIM.
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Old 3rd September 2009, 01:21 PM   #893
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Yes, but I'm afraid it would be useless. Nobody ever won an argument against you, and unfortunately not because you are always right, but because you won't ever admit you are wrong.

You failed again in adding any argument to your extraordinary claims regarding PIM.
There are any number of easily obtained references. http://www.st-andrews.ac.uk/~jcgl/Sc...t12/page1.html

Getting non-harmonicly related output remains an extraordinary claim.
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Old 3rd September 2009, 02:28 PM   #894
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Hi

Just a link to an online book:

MATHEMATICS OF THE
DISCRETE FOURIER TRANSFORM (DFT)
WITH AUDIO APPLICATIONS
SECOND EDITION

Cheers

http://www.dsprelated.com/dspbooks/mdft/
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File Type: jpg MDFT.jpg (8.6 KB, 228 views)
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Old 3rd September 2009, 03:44 PM   #895
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Everyone, I am not the discoverer of the PIM interspersed with TIM.
It was Mitch Cotter, who first pointed it out to me, recently, and he told me that he showed Matti Otala the same thing (perhaps on a different graph), more than 30 years ago. This is apparently what got Matti Otala on the path of including PIM into the group as an important distortion source.
Mitch Cotter has a strong FM background and is associated with the design of the Marantz 10B tuner along with Dick Sequerra.
Now, sorry about 'name dropping' but these are the people who I have had 1 hour or more conversations about this subject in the last 24 hours. Sorry, I didn't speak to Saul Marantz, as he is deceased and he couldn't help much anyway, since he wasn't really technical.
These are my peers, and they have been for the last 25 years.
Bessel was a little before my time, and I would have taken Heaviside's position on just about everything, in any case. Fourier, what a guy!
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Old 3rd September 2009, 03:58 PM   #896
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Thank Stinius, anything from CCRMA is interesting to me. I was just reading an article in the latest IEEE 'Spectrum' Sept. 2009, p. 24 last night about a guy from CCRMA who does interesting things there. Perhaps this will give me a bigger clue as to the subtle differences between DFT and FFT. Any real tradeoffs in info?
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Old 3rd September 2009, 04:37 PM   #897
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Quote:
Originally Posted by john curl View Post
Everyone, I am not the discoverer of the PIM interspersed with TIM.
It was Mitch Cotter, who first pointed it out to me, recently, and he told me that he showed Matti Otala the same thing (perhaps on a different graph), more than 30 years ago. This is apparently what got Matti Otala on the path of including PIM into the group as an important distortion source.
Mitch Cotter has a strong FM background and is associated with the design of the Marantz 10B tuner along with Dick Sequerra.
Now, sorry about 'name dropping' but these are the people who I have had 1 hour or more conversations about this subject in the last 24 hours. Sorry, I didn't speak to Saul Marantz, as he is deceased and he couldn't help much anyway, since he wasn't really technical.
These are my peers, and they have been for the last 25 years.
Bessel was a little before my time, and I would have taken Heaviside's position on just about everything, in any case. Fourier, what a guy!
John, did these people give you hard factual data and arguments for their position? If so, why don't you just give them here and teach us all something? Or did you just believe them on their blue eyes and expect everyone else to do the same?

jd
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Old 3rd September 2009, 05:15 PM   #898
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They convinced me, already. But then I am more willing to learn new things, and accept that some people actually know more than me about it. I do have a call into Mitch Cotter. He is tied up on his project, but I did leave a message asking for further details, just 1/2 hour ago. It may be until tomorrow, before I hear from him. I have tried over the last 18 hours, already.
Personally, I don't need to convince anyone here about anything. It is your gain or loss to follow up. It is now obvious to me, but it is because I participated in presenting the original graph, and did dozens of separate measurements, myself, in Matti's lab, getting the same graphs. I KNOW the test procedure, and its correctness.
What Mitch Cotter contributed, was NOTING the FM distortion as it would appear on the same graph. He showed Matti, Matti verified it, himself, (didn't tell me), thanked Mitch, then wrote his first paper on PIM, ALL math, no measurements. I just met up with Mitch a few months ago, and we talk almost every day. Does this help?
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Old 3rd September 2009, 06:02 PM   #899
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I would like to see the math for the non-harmonically related frequencies or how three orders of magnitude more PM in a speaker than an average amplifier does not matter.

This would be good technical stuff that would interest everyone I would think. I would hope "we just hear this stuff" is not the fall back position.
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Old 3rd September 2009, 06:04 PM   #900
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Originally Posted by john curl View Post
They convinced me, already. But then I am more willing to learn new things, and accept that some people actually know more than me about it. I do have a call into Mitch Cotter. He is tied up on his project, but I did leave a message asking for further details, just 1/2 hour ago. It may be until tomorrow, before I hear from him. I have tried over the last 18 hours, already.
Personally, I don't need to convince anyone here about anything. It is your gain or loss to follow up. It is now obvious to me, but it is because I participated in presenting the original graph, and did dozens of separate measurements, myself, in Matti's lab, getting the same graphs. I KNOW the test procedure, and its correctness.
What Mitch Cotter contributed, was NOTING the FM distortion as it would appear on the same graph. He showed Matti, Matti verified it, himself, (didn't tell me), thanked Mitch, then wrote his first paper on PIM, ALL math, no measurements. I just met up with Mitch a few months ago, and we talk almost every day. Does this help?
John,

The question remains, how do you or anyone else know that the blip is due to PIM or something else?

You assert that this blip must be PIM because is is not related in an N/M way to the frequencies in the test. Ask one of your friends to explain why this is the case.

It is also very unclear how a non-N/M product can be created by this test.

Just saying it is so does not make it so. Just having your colleagues or some famous person say it is so and then have it repeated second-hand by you does not make it so. You asserted that Barrie Gilbert's paper proved your point on PIM. That is not so, even though Barrie did not make any mistakes. I frankly think that you are very much in the habit of putting your own spin on what others say.

Cheers,
Bob
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