fiddled filter design

An issue, but not a problem.

  1. With lots of design jobs there will be lots of random starting points.
  2. As compute power improves, the plan will switch to starting with a whole pile of random circuits & evolving lots in parallel rather than just 1.

NT

Reply to
tabbypurr
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Not everything in the world has been shaved by Mr. Occam's razor, though most have.

Reply to
tabbypurr

Organisms that use dumb evolution will be lunch for organisms that use smart evolution. Evolution itself evolves; why wouldn't it?

And Occam's Razor is not a law of nature. Even the simplest bacteria is stunningly complex, too complex for us to understand yet.

If you insist something is not likely, you probably won't be the guy who discovers it.

My eyes and ears and kidneys are (currently) indistinguishable from magic.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

Well... not really... the fundamental reason these filter came about was because they have closed form solutions of arbitrary order to satisfy a key specification. It was because there were no computers at the time

Today, its more down to laziness why other structures are not used.

Actually, the Bessel filter was invented to solve the perfect delay, linear phase problem. The fact that it rolls off was a nuisance in its original construction. It was to synthesis of exp(-tau.s). It wasn't meant to be an amplitude filter at all.

With that in mind, the optimum 2nd order delay filter has a Q=2/pi, which is not the same as a Bessel order two. This number is found by doing a min/max analyses, which escapes me right now... I was 21 when I first came across that result, which was one or two years ago...

The "best" filters are ones where a brute force, vary all components (say by a genetic algorithm for example) is used to satisfy the desired specs.

Most of those high brow "optimum" filter theorems are really just seeking an accomplice to filters that are not actually the real best. Its a "best in class" sort of thing, where the class is whatever it needs to be to have the claim "best".

I am aware of some work that had genetic algorithms re-discover the classis filters, and generate new, better ones that were, patentable.

-- Kevin Aylward

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Reply to
Kevin Aylward

Do you have NuHertz?

Bingo.

Actually, proof is probably a lot more boring than that. You can interpolate the trajectory of poles between configurations in a very straightforward way. The standard types all have poles lying on an ellipse enclosing the origin, giving two degrees of freedom (offset and eccentricity).

Well, for a given set of constraints (e.g., amplitude and phase flatnesses, sharpness of cutoff or stopband attenuation), there's probably a global minima which is slightly off an intermediate ellipse, and therein would lie the difficulty.

Tim

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Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Design 
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Reply to
Tim Williams

We have their LC filter designer. The UI is clunky but it makes great filters.

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John Larkin         Highland Technology, Inc 
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Reply to
John Larkin

Smart organisms, whatever that might mean, also get eaten.

What on earth do you mean by "evolution evolves"?

Occam's Razor is a good principle. It is the core of the scientific method and is one of the guiding concepts that enabled us to progress beyond superstition.

I certainly won't discover it, because it isn't my subject area.

But I am open to somebody competent discovering it and - most importantly - providing convincing proff.

Well that's certainly 90 degree swerve, so I'll do another.

All three eyes? I have three eyes and I expect you do too.

My extremely primitive third eye has saved me from injury on countless occasions.

Hint: it is more primitive that those found in a pit viper.

Reply to
Tom Gardner

A perfect delay, infinite bandwidth unity-gain filter sounds like a violation of conservation of energy to me. Maybe that's not what you meant tho

Reply to
bitrex

other day what sort of new topologies & improvements it might bring.

The tricky bit is defining what you want the evolutionary process to achiev e.

Software development has thrown up specification languages, which let you d efine what you want a program to do in terms that can be plugged into a sys tem that that can prove that a program will do what you want it to do.

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is one example. There are others. They don't seem to be all that popular.

A lot of the work in developing new hardware is taken up by finding out wha t it needs to do, and what it must not do if anything goes wrong.

Darwinian evolution cheats by specifying only that it wants the evolving sp ecies to survive, and you get absurdities like the peacocks tail, or Donald Trump's persuasive powers, which are clearly blind alleys, or would be if anything invovled in generating them could think about what was going on..

--
Bill Sloman, Sydney
Reply to
bill.sloman

Not everything in NT's world has been shaved by Eillian of Occam's razor, because NT's world includes quite a lot of fantasy (which he doesn't recognise as such).

He's clearly in the gullible category (along with Cursitor Doom and John Larkin) but he's less willing to provide links to the people who generate his favourite fantasies.

--
Bill Sloman, Sydney
Reply to
bill.sloman

Sadly, there don't seem to be any examples around of creatures that use smart evolution.

Evolution has evolved us, and we have just discovered the tools that would let us implement intelligent design, so in a sense John Larkin is right, but he has never been able to come up with any examples of his "smart" evolution in action.

Not exactly true.

But insisting that something is "likely" without having any supporting evidence is what you do when you start up a religion.

John Larkin isn't really prophet material.

John Larkin doesn't know much about biology.

--
Bill Sloman, Sydney
Reply to
bill.sloman

You say "us" as though JL also has progressed beyond superstition. His posts suggest otherwise :P

Reply to
Clifford Heath

Yes. Sometimes genetics or annealing can help overcome local maxima, by jolting or jumping out of them. But in other domains, brute force and slope descent are perfectly adequate.

A friend designed a truly excellent direction-finding antenna for the UHF ham band (which is quite wide) by wrapping such a thing around NEC, and using it to run about a million field simulations while tweaking the antenna elements. The heuristic measure is not gain, not front-to-back ratio, it's continuity of the directional effect due to the lack of prominent side-lobes (including polarisation effects because reflections can give you all kinds of crap). This means you can get a nice ellipse with the biggest point in the right direction, and no side-lobes to throw you off. Believe me, you do *not* want to be hiding your use of a UHF radio from this guy :), or competing against him to find such.

Clifford Heath.

Reply to
Clifford Heath

"Us" in the sense that I can say "we" have two legs, even though the mean number is slightly lower :)

Reply to
Tom Gardner

Its called an ideal transmission line :-)

Somewhat annoyingly, recently discovered Cadence Virtuoso/Spectre have made what is, a standard Spice T line non functional. Replaced it with a bloody way too complicated mtline which for the life of me cant figure out how to set it up. As a stop gap, I used my SuperSpice automatic filter generator to generate a 4th order Bessel as a compromise. A/B ing with a TLine in SS shows really good phase matching.....

-- Kevin Aylward

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Reply to
Kevin Aylward

I disagree. Our own brains are indeed "biological life", and also operate as a Darwinian Machine within a Darwinian Environment. There is nothing special about our brains, there are still a 100% result of natural processes.

We, apparently as damit, have algorithms that that have evolved to be extremely goal directed. We go to work to pay the hookers etc...

In the larger schemes of things, nature might be argued to have no "goal", but the biological machines (animals with brains) that have evolved, certainly do by any pragmatic definition of "goal" or "purpose". Algorithms have arose, that "want" to achieve a purpose. If this were not so, we would not exist.

I would note though that the random variation part of the GA is the only bit that can generate truly new information. That is, solve a problem with information that cannot be derived from simply copying and manipulating existing information.

Which is somewhat interesting in itself, either one copies something and piddles with it, hardly a measure of greatness or one randomly generates something that is inventive". However, if it is random, we cant really feel great about that either....

Yep... Free will don't exist....

-- Kevin Aylward

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Reply to
Kevin Aylward

You bring up an interesting point about just needing to work. The effort o f engineering is getting something to work with minimal resources, however, most of the time it is better to make things work with lots and lots of ma rgin. In my business wasting resources (ie extra parts cost)is not a big d eal because we sell high margin products.

Control loops are my favorite. I like control loops to be as slow as possi ble Super damped response, if the application allows for it. In our text b ooks we were taught to have the "ideal" loop of 45 degrees of phase margin with a couple (3) dB of overshoot. Now I realize that if I need a loop lik e that I am probably going to have problems because that is going to be pro blematic in production or over temperature etc.

I agree that a filter that works is adequate. However, filters are one of the easiest things for non experts to get close to right due to all the sof tware tools available (that actually get it right)

Reply to
blocher

snipped-for-privacy@columbus.rr.com wrote

Exactly, much better. And equipment should be 'repairable', so selected components that just meet specs are out.

Agreed. Never save on parts! Make the design with a safety margin.

Reply to
<698839253X6D445TD

Occam's Razor says that the simplest idea *that you can imagine* is probably the correct explanation for a causality. That's absurd from a number of aspects. Reliance on it would stop science in its tracks.

I design original things. They work.

We couldn't work together. You two are hostile to new ideas and I am hostile to boring ideas.

We don't understand how a one-cell critter works, much less human consciousness. I think amazing things remain to be discovered. You probably don't.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

That's culture, not biology. Nobody is born knowing how to go to work or what a hooker is or that you need to pay them.

I'm sure someone has proposed a biological-analogy to "evolution" of cultures (memes?) but the supporting evidence to construct a falsifiable theory of how that actually occurs in practice in a universal sense, invariant to particular human cultures (which vary rather widely) seems pretty lacking as compared to biological natural selection.

"Man can do as he wills, but he cannot _will_ what he wills"

Reply to
bitrex

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