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Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
References: <email@example.com> <3DB2E3CE.firstname.lastname@example.org> <email@example.com> <3DB41488.firstname.lastname@example.org> <3DB43497.A32B8380@webaccess.net> <3DB45343.E61C1CCB@webaccess.net> <3DB466BC.593D4D35@webaccess.net> <3DB5452A.B792F3AC@webaccess.net> <3DB55886.9865D8D1@webaccess.net> <3DB89837.5FFFA3BF@webaccess.net>
Subject: Re: How does a mixer work?
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X-Inktomi-Trace: public1-pete2-5-cust19.pete.broadband.ntl.com 1035526711 30990 18.104.22.168 (25 Oct 2002 06:18:31 GMT)
Date: Fri, 25 Oct 2002 07:18:30 +0100
NNTP-Posting-Date: Fri, 25 Oct 2002 07:18:31 BST
"Chuck Simmons" wrote in message
> Kevin Aylward wrote:
> > "Chuck Simmons" wrote in message
> > news:3DB55886.9865D8D1@webaccess.net...
> > > Kevin Aylward wrote:
> > > >
> > > > The mathematics "prove" that there is an inherent measurement
> > problem in
> > > > the real world. You cannot measure frequency 100% accurately,
> > without
> > > > taking infinite time.
> > >
> > > No, you are reversing the implication. The "proof" of your
> > > requires inserting an underlying physical context which is not in
> > > mathematics. The physical context spuriously inserted is physical
> > > measurement error.
> > You misunderstand the basics. The uncertainty relation
> > nothing to do with a physical measurement error, in the sense of
> > imperfect equipment. The assumption is that the measuring equipment
> > ideal. The issue is with the representation of signals.
> I do not misunderstand the basics.
Yes you do. You do not understand that short pulses require large BW.
The uncertainty relation introduces a
> physical context by adding noise to the signal.
Noise is not a
> mathematical concept precisely except that it is considered
I explained in another reply to one of your posts that noise is not
e.g. short pulse require large BW, so that pulse width*BW is not
arbitrary. The shorter the pulse, the larger the BW, i.e. short pulses
have large Fourier transform spreads, and long pulses have narrow BW,
i.e, if you require a narrow BW, i.e. to measure a frequency accurately,
it takes a lot of time.
This is expressed by Sigma_F * Sigma_T >=1/2. The standard deviations
are determined by the shape of the pulse and the shape of the pulses
Fourier transform. Noise is not involved at all.
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
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