> Jerry Avins <jya@ieee.org> writes:
>
>> You didn't write that *consistently* and I took you at your word?
>
> I think the truth is that you're being obstinate. Perhaps that has
> been obvious to everyone and this has all been a circus. One thing is
> for certain: I regret having spent the time attempting to communicate
> with you, and I'll not make that mistake again.
My loss then. I had hoped we might meet someday and have a beer.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Randy Yates●June 6, 20072007-06-06
Jerry Avins <jya@ieee.org> writes:
> You didn't write that *consistently* and I took you at your word?
I think the truth is that you're being obstinate. Perhaps that has
been obvious to everyone and this has all been a circus. One thing is
for certain: I regret having spent the time attempting to communicate
with you, and I'll not make that mistake again.
--
% Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven.
%% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and
%%% 919-577-9882 % Verdi's always creepin' from her room."
%%%% <yates@ieee.org> % "Rockaria", *A New World Record*, ELO
http://home.earthlink.net/~yatescr
Reply by Jerry Avins●June 6, 20072007-06-06
Randy Yates wrote:
> Jerry Avins <jya@ieee.org> writes:
>
>> You may have intended filter and decimator, but you didn't write
>> that.
>
> Oh really? Do you remember this post?
>
> From: Randy Yates <yates@ieee.org>
> Subject: Re: AM demodulation using DSP
> Newsgroups: comp.dsp
> Date: Sun, 03 Jun 2007 14:29:31 -0400
> Organization: The Universal Church of Christ
>
> Jerry Avins <jya@ieee.org> writes:
>
> > c1910 wrote:
> >> hi!
> >> i want to demodulate AM signal digitally...
> >> i want to use a digital filter to separate the carrier and the information
> >> signal. i've searched a lot...and i haven't found the answer.
> >> can anyone help?please...
> >> thx...
> >
> > The last time you asked this question, you were told that you can't
> > demodulate with a filter. The laws of physics haven't changed in th
> > last week or so.
>
> Well, actually you could with a filter and decimator, if your sample
> rate is just right...
You didn't write that *consistently* and I took you at your word? Do I
detect animus? Why?
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Randy Yates●June 6, 20072007-06-06
Jerry Avins <jya@ieee.org> writes:
> You may have intended filter and decimator, but you didn't write
> that.
Oh really? Do you remember this post?
From: Randy Yates <yates@ieee.org>
Subject: Re: AM demodulation using DSP
Newsgroups: comp.dsp
Date: Sun, 03 Jun 2007 14:29:31 -0400
Organization: The Universal Church of Christ
Jerry Avins <jya@ieee.org> writes:
> c1910 wrote:
>> hi!
>> i want to demodulate AM signal digitally...
>> i want to use a digital filter to separate the carrier and the information
>> signal. i've searched a lot...and i haven't found the answer.
>> can anyone help?please...
>> thx...
>
> The last time you asked this question, you were told that you can't
> demodulate with a filter. The laws of physics haven't changed in th
> last week or so.
Well, actually you could with a filter and decimator, if your sample
rate is just right...
--
% Randy Yates % "She has an IQ of 1001, she has a jumpsuit
%% Fuquay-Varina, NC % on, and she's also a telephone."
%%% 919-577-9882 %
%%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr
???
--
% Randy Yates % "Maybe one day I'll feel her cold embrace,
%% Fuquay-Varina, NC % and kiss her interface,
%%% 919-577-9882 % til then, I'll leave her alone."
%%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr
Reply by Jerry Avins●June 6, 20072007-06-06
Randy Yates wrote:
> Jerry Avins <jya@ieee.org> writes:
>
>> Eric Jacobsen wrote:
>>
>> ...
>>
>>> FWIW, I followed your description and the relevance to the OP topic
>>> well enough, and even got an Aha! out of using the carrier forced into
>>> limiting as the sampling clock to make an automatic synchronous demod.
>>> Presto...filterless AM demodulation.
>> I'm delighted to have been able to contribute an aha. Sort of like an
>> unexpected bit of candy.
>>
>>> I think Randy just had a different model or pov in mind.
>> Randy likes things neat and clean.
>
> I generally approach design by first formulating a theoretical
> approach, then iterating between practical considerations and
> corresponding modifications to the theory. This is based on the basic
> idea that if it isn't doable in theory, it isn't doable at all.
>
> So when you start bringing up things like diodes when we don't even
> have a clear indication that we understand or agree on the ideal block
> diagram level, I get a little worried that we're not on the same page.
The diodes came into the discussion in the guise of of a ring modulator,
which I put forward as a practical alternative to the linear
multiplier that you brought up. I wasn't trying to sandbag you; I hope
you're not aggrieved.
> Not to mention that you never acknowledged that my statement was
> indeed correct and spoke, at least in spirit (since it's a filter AND
> a decimator, not just a filter), to the OP's initial inquiry.
You may have intended filter and decimator, but you didn't write that. I
don't quite see how decimation helps, but I didn't argue that. (A
decimator works with existing samples, but special samples are needed
for my scheme; they must be synchronous.)
>> The real world can be sloppy. Sometimes, like sex, it can be more
>> fun that way! :-)
>
> I like my sex sloppy, but I like my engineering clean. ;)
Seriously, when the bandwidth of the IF or the sampler itself is narrow
enough to exclude images, adding a filter to remove what isn't there
shouldn't qualify as clean engineering.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Randy Yates●June 5, 20072007-06-05
Jerry Avins <jya@ieee.org> writes:
> Eric Jacobsen wrote:
>
> ...
>
>> FWIW, I followed your description and the relevance to the OP topic
>> well enough, and even got an Aha! out of using the carrier forced into
>> limiting as the sampling clock to make an automatic synchronous demod.
>> Presto...filterless AM demodulation.
>
> I'm delighted to have been able to contribute an aha. Sort of like an
> unexpected bit of candy.
>
>> I think Randy just had a different model or pov in mind.
>
> Randy likes things neat and clean.
I generally approach design by first formulating a theoretical
approach, then iterating between practical considerations and
corresponding modifications to the theory. This is based on the basic
idea that if it isn't doable in theory, it isn't doable at all.
So when you start bringing up things like diodes when we don't even
have a clear indication that we understand or agree on the ideal block
diagram level, I get a little worried that we're not on the same page.
Not to mention that you never acknowledged that my statement was
indeed correct and spoke, at least in spirit (since it's a filter AND
a decimator, not just a filter), to the OP's initial inquiry.
> The real world can be sloppy. Sometimes, like sex, it can be more
> fun that way! :-)
I like my sex sloppy, but I like my engineering clean. ;)
--
% Randy Yates % "How's life on earth?
%% Fuquay-Varina, NC % ... What is it worth?"
%%% 919-577-9882 % 'Mission (A World Record)',
%%%% <yates@ieee.org> % *A New World Record*, ELO
http://home.earthlink.net/~yatescr
Reply by Jerry Avins●June 5, 20072007-06-05
Eric Jacobsen wrote:
...
> FWIW, I followed your description and the relevance to the OP topic
> well enough, and even got an Aha! out of using the carrier forced into
> limiting as the sampling clock to make an automatic synchronous demod.
> Presto...filterless AM demodulation.
I'm delighted to have been able to contribute an aha. Sort of like an
unexpected bit of candy.
> I think Randy just had a different model or pov in mind.
Randy likes things neat and clean. The real world can be sloppy.
Sometimes, like sex, it can be more fun that way! :-)
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by glen herrmannsfeldt●June 5, 20072007-06-05
Eric Jacobsen wrote:
(snip)
> One doesn't need to avoid aliasing entirely, only enough to get the
> job at hand accomplished. It is, after all, impossible to completely
> eliminate aliasing, theoretically, but one can get well within the
> range of practicality.
And sometimes not at all. People seem to live with the wagon
wheel in the movies effect, possibly due to the difficulty of
making a filter to remove it.
-- glen
Reply by Vladimir Vassilevsky●June 5, 20072007-06-05
Eric Jacobsen wrote:
> FWIW, I followed your description and the relevance to the OP topic
> well enough, and even got an Aha! out of using the carrier forced into
> limiting as the sampling clock to make an automatic synchronous demod.
> Presto...filterless AM demodulation.
This method is commonly used for the analog video demodulation in the
ICs for the TV. Its virtue is in the good linearity, especially if the
carrier frequency is comparable to the modulation frequency.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
Reply by Eric Jacobsen●June 5, 20072007-06-05
On Tue, 05 Jun 2007 11:58:21 -0400, Jerry Avins <jya@ieee.org> wrote:
>Randy Yates wrote:
>
> ...
>
>> I can't believe we're having this discussion. One of us (and it
>> could be me) is missing something very basic.
>
>According to theory, I'm wrong. If I build what I prescribe, it will
>work because all the filtering needed is had simply by not sweating a
>broadband design.
>
>Jerry
Which works consistent with theory because all systems are, after all,
bandlimited.
So I don't agree that you're wrong according to theory. Your scheme
wouldn't work in a conceptual, ideal system that had aliasable energy
at specific frequencies. One would have to go out of their way to
build such a system, though, as the ADC and a host of other components
would need to support bandwidths way beyond the range useful for the
application. Once the effects of practical devices are taken into
account, your system would seem to hold up to theory quite well.
One doesn't need to avoid aliasing entirely, only enough to get the
job at hand accomplished. It is, after all, impossible to completely
eliminate aliasing, theoretically, but one can get well within the
range of practicality.
FWIW, I followed your description and the relevance to the OP topic
well enough, and even got an Aha! out of using the carrier forced into
limiting as the sampling clock to make an automatic synchronous demod.
Presto...filterless AM demodulation. I think Randy just had a
different model or pov in mind.
Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org