Discrete-time systems

On 11/5/2012 7:41 PM, dbd wrote:
> On Monday, November 5, 2012 8:52:02 AM UTC-8, rickman wrote:
> ...
>> I'm not sure exactly what your point is.  But the issue of delay in
>> filters is fundamentally related to the process of measurement.  The
>> filter does not need to produce an intermediate result that itself can
>> be observed.
>>
>> The delay in a filter is a fundamental result of the resolution of a
>> property which is based on time.
>>
>> Rick
>
> In engineering, a measurement is the determination of the ratio of a physical parameter to a standard unit for that parameter. Resolution is, for example:
>   "The act or process of separating or reducing something into its constituent parts" http://www.thefreedictionary.com/resolution
>
> I think that Ls, Rs , and Cs in simple passive networks are able to filter and delay perfectly well without performing any measurement or resolving anything into constituent parts. I think such filters work on the properties of Ls, Rs, and Cs and don't require any metaphysical hand waving about 'measurements' or 'resolution'. If you want to understand or predict performance, I think you should look at the values of the Ls, Rs, and Cs and not some 'fundamental' metaphysics. There are functional physical interpretations.
>
> Dale B. Dalrymple

You are a funny one.  Perhaps Heisenberg should have consulted with you 
on what limits the resolution of a microscope?  I'm sure you could just 
tell him is is the way the lens focuses the light...

Ok, use a different word then.  But the concept is valid.  A filter 
takes time to resolve frequencies proportional to the degree of accuracy 
required because the property frequency is a function of time.

Rick

On Tuesday, November 6, 2012 11:08:50 AM UTC-8, rickman wrote:
> ...
> You are a funny one.  Perhaps Heisenberg should have consulted with you 
> on what limits the resolution of a microscope?  I'm sure you could just 
> tell him is is the way the lens focuses the light...
> 

In physics as well as engineering, there is no measurement if no observable is generated. The Heisenberg uncertainty principle is a relationship between the statistics of observations. To resolve is also to measure, if there is no observable, there was no 'resolution'.

> 
> Ok, use a different word then.  But the concept is valid.  A filter 
> takes time to resolve frequencies proportional to the degree of accuracy 
> required because the property frequency is a function of time.
> 
> Rick

"To resolve" has a long history on comp.dsp of discussions between participants with strongly held beliefs in metaphysical definitions that they cannot state coherently and can't explain to each other because they don't define an observable and can't see each others hands waving on the internet. If you feel the need for metaphysical juju to feel good about the equations, don't co-opt words that have useful engineering meanings or people may talk :).

Dale B. Dalrymple

On 11/6/2012 3:13 PM, dbd wrote:
> On Tuesday, November 6, 2012 11:08:50 AM UTC-8, rickman wrote:
>> ...
>> You are a funny one.  Perhaps Heisenberg should have consulted with you
>> on what limits the resolution of a microscope?  I'm sure you could just
>> tell him is is the way the lens focuses the light...
>>
>
> In physics as well as engineering, there is no measurement if no observable is generated. The Heisenberg uncertainty principle is a relationship between the statistics of observations. To resolve is also to measure, if there is no observable, there was no 'resolution'.

This went way over your head.  Dig around a little bit and learn what 
led Heisenberg to the discovery of the uncertainty principle.  It is not 
an easy search, so I'll give you a hint.  First learn about his oral 
exam following his dissertation acceptance.  He almost flunked.  What 
were the questions?


>> Ok, use a different word then.  But the concept is valid.  A filter
>> takes time to resolve frequencies proportional to the degree of accuracy
>> required because the property frequency is a function of time.
>>
>> Rick
>
> "To resolve" has a long history on comp.dsp of discussions between participants with strongly held beliefs in metaphysical definitions that they cannot state coherently and can't explain to each other because they don't define an observable and can't see each others hands waving on the internet. If you feel the need for metaphysical juju to feel good about the equations, don't co-opt words that have useful engineering meanings or people may talk :).
>
> Dale B. Dalrymple

Wow, we are on our high horse today.  Which word did I "co-opt" with 
metaphysical "ju-ju"?  The concepts I am talking about have nothing to 
do with the equations of e&m.  They have to do with time related 
properties.  Is time "metaphysical"?

Rick

On Tuesday, November 6, 2012 6:30:11 PM UTC-8, rickman wrote:
...
> 
> > "To resolve" has a long history on comp.dsp of discussions between participants with strongly held beliefs in metaphysical definitions that they cannot state coherently and can't explain to each other because they don't define an observable and can't see each others hands waving on the internet. If you feel the need for metaphysical juju to feel good about the equations, don't co-opt words that have useful engineering meanings or people may talk :).
> >
> > Dale B. Dalrymple
> 
> Wow, we are on our high horse today.  Which word did I "co-opt" with 
> metaphysical "ju-ju"?  The concepts I am talking about have nothing to 
> do with the equations of e&m.  They have to do with time related 
> properties.  Is time "metaphysical"?
> 
> Rick

A measurement that doesn't produce an observable is not physical, it is metaphysical. To resolve without producing an observable is not physical, it is metaphysical. Your insistence  on unobservable (and undefined, perhaps undefinable) operations on time taking place inside filters is clearly an argument for metaphysics. You are right, your concepts are not about representations of physics, so of course your concepts of time can be correctly labelled metaphysical instead. In an engineering titled forum I think it is appropriate to notice the difference between physical arguments and metaphysical arguments. I haven't agreed or disagreed (or believed or not believed). I can't, because your 'time related properties' have no definition. If your 'measure' and 'resolve' within simple passive filters have physical definitions, what are they? Give us the view from up on your horse, please!

Dale B. Dalrymple