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Re: fiddled filter design
On 12/11/18 12:20 am, Jeroen Belleman wrote:
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Well then, use a circulator. Assuming it's feasible in the target  
frequency range :)

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What's the topology of the five components? Sorry, I probably know it,  
but would prefer you were more specific.

Clifford Heath.

Re: fiddled filter design
On 11/11/18 22:11, Clifford Heath wrote:
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The purpose of matching is to obtain flat, constant impedance
over frequency. Circulators are narrow band devices. I count
bandwidth in decades.


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Nothing very impressive, really. It's a series RC in parallel with
a series RLC. For most tame filters, the theoretical S11 never
goes over -50dB. I think this is useful. I wrote it up in
<http://cern.ch/jeroen/crfilter/crfilter.html .

Jeroen Belleman


Re: fiddled filter design
On 12/11/18 8:52 am, Jeroen Belleman wrote:
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Saved, thank you.

Clifford Heath.


Re: fiddled filter design
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Interesting, yes that open possibilities for high current / low current
loss improvement.

Re: fiddled filter design
On 09/11/2018 15:35, John Larkin wrote:
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One place I worked had a very good genetic optimiser that could be  
wrapped around their in-house SPICE. You basically give it a netlist,  
tell it which components it is allowed to fiddle with, which simulations  
to run (which could be anything that SPICE can simulate), and give it  
some expressions for things you want it to minimise or maximise (which  
could be quite complicated functions to evaluate what you really care  
about), and tell it to go for it. So on a chip you might give it an  
expression for total capacitance value, and tell it to minimise that  
since that will affect chip size and so the die cost, and give it  
expressions for group delay, noise, time-domain behaviour or whatever  
you care about. I no longer recall the exact details of how the goals  
had to be expressed. It starts with a random population of circuits, and  
evaluates how "good" each one is, then picks some of the best ones from  
that generation and "breeds" them somehow, to make the next generation.  
The first time I tried it, I gave it a filtering problem that I had been  
struggling with, and after a few thousand generations (iirc a few  
minutes of runtime) it totally kicked my butt and came up with a much  
better filter than I had been able to design in the previous several  
weeks. I recall other people had used it to design high-speed logic  
cells (letting it tweak the transistor sizes, adding estimated  
parasitics and simulating the maximum clock frequency) and it came up  
with some non-intuitive things that were faster than what we had found  
by usual methods. If I had ever suffered from any lingering doubt about  
whether evolution really could be responsible for all the plants and  
animals in a feasible number of generations, the experience of using  
that software totally cured it. Just a few CPUs in a small compute farm,  
in a few minutes, could easily out-design what I could do, so billions  
of lifeforms running in parallel, for a few billion years, ought to come  
up with some impressive things.




Re: fiddled filter design
On Friday, 9 November 2018 11:41:51 UTC, Chris Jones  wrote:
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That process will become standard/universal one day. I was wondering the other day what sort of new topologies & improvements it might bring.


NT

Re: fiddled filter design
On 09/11/2018 12:40, snipped-for-privacy@gmail.com wrote:

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Trouble is, genetic algorithms lead to local maxima, not global.  Who's  
to say that a rejected 'bad' result wouldn't have eventually led to a  
better outcome?

Not that I have a better idea.

Cheers
--  
Clive

Re: fiddled filter design
On 11/09/2018 12:09 PM, Clive Arthur wrote:
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They're also not the only biologically-inspired optimization game in  
town, there are many types of biologically-inspired algorithms, some  
which perform better looking at the global space and others which are  
better at refinement.

No law anywhere that says you can't employ a hybrid strategy using  
something like a stochastic/Monte Carlo simulation to find the likely  
domain of a local optimum and then use an evolutionary algorithm to hone  
in on it.

<https://en.wikipedia.org/wiki/Memetic_algorithm

Re: fiddled filter design
On Friday, 9 November 2018 17:09:35 UTC, Clive Arthur  wrote:
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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

Re: fiddled filter design
On Friday, November 9, 2018 at 11:40:57 PM UTC+11, snipped-for-privacy@gmail.com wrote:
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<snip>

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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.

https://en.wikipedia.org/wiki/Z_notation

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

Re: fiddled filter design
On 11/09/2018 06:41 AM, Chris Jones wrote:

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I mean other than the fact that the only real competing theories are  
variants on "God did all or some of it by magic all at once at some  
point" which apparently even the current Pope is not in favor of as a  
sensible concept of how a God, who even in just some existential sense  
might "care" about how intelligent life perceives the Universe, would  
operate.

or as a Christian theologian might put it if there are no doubts about  
anything then there can also be no faith, no grace, no salvation either  
you kinda got nothin' to work with from a religious perspective - you  
have to have both sides of the coin it's a package deal.

And I try to keep in mind that while genetic algorithms are impressive  
in what they can accomplish in engineering problems they are leveraged  
differently than how life in the real world operates from an  
evolutionary perspective. The genetic-algorithm-style evolution is  
highly goal-directed towards a fixed target, an optimal solution to some  
engineering problem. Biological life style evolution is not  
goal-directed and there is no fixed target.

The former is more like the notion of "intelligent design" where God has  
some idea of what an ideal "fern" should be and sets the parameters up  
such that after a few million generations a nice fern pops into  
existence, hardly a surprising thing really cuz it was set it up that  
way, same with a good-performing filter. It's finally an entirely  
mechanical process where the outcome is pre-ordained, just that you  
didn't know what the outcome would look like exactly a priori doesn't  
mean that it's not pre-ordained from your input parameters.

That it works at all surely gives a lot of credence to the scientific  
concept of _natural selection_ being valid but IMO finally has little to  
say about how _evolution_ works in the real world or why ferns or people  
currently exist in the state they do, it's not a proof of anything.











Re: fiddled filter design

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Natural selection is almost surely the mechanism that steers
evolution, but I think that variation is not random. There is
intelligence in the process. Maybe not some white-bearded guy up in
heaven, but far more sophisticated DNA algorithms than waiting for a
cosmic ray to smash a chromosone somewhere. A form of quantum
computing probably.

Organisms can't, and don't, wait for a survival challenge before they
get around to mutating and adapting and hoping that some of their
descendents will survive to propagate their mutation. If they did,
they'd be extinct.


--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: fiddled filter design
On 09/11/2018 17:13, John Larkin wrote:

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I don't think any evolutionary scientist would disagree with that.

Cheers
--  
Clive

Re: fiddled filter design
On a sunny day (Fri, 9 Nov 2018 17:19:39 +0000) it happened Clive Arthur

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I found this interesting:
 https://www.sciencedaily.com/releases/2018/11/181108142323.htm

Re: fiddled filter design
On 11/09/2018 12:13 PM, John Larkin wrote:
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I'm perfectly fine with some "why things are" questions remaining  
unanswerable by science, either for just the near future or for always.  
It will likely always be so

Re: fiddled filter design
On 09/11/18 17:13, John Larkin wrote:
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Random variation is a /sufficient/ mechanism. Postulating more
runs against Occam's Razor.

Now there may be alternative mechanisms, but it is necessary to
define them and then to show that they do explain something that
random mutation can't.


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Ah. Magic. Or something that is (currently) indistinguishable
from magic.

Why not claim that Maxwell's daemons are responsible for
electronic circuit's behaviour :)


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Ah yes, Lamarckian inheritance.

It currently looks like the plain-vanilla genetic inheritance
mechanisms are too simplistic. I'll mention epigenetics, without
really understanding it.

However none of the "new mechanisms" require the addition
of greybeards, FSMs[1], or things that have made Fritjof
Capra (in)famous.

[1] No, not finite state machines!

Re: fiddled filter design
On 11/09/2018 12:32 PM, Tom Gardner wrote:

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Of course. The thrust of my original post was that the fact toy models  
of natural selection operating to design a filter is one of those things  
that might sometimes lead a former "evolution-skeptic" to believe  
similar techniques could be deployed to "engineer" the perfect human.  
Which is nonsense

Re: fiddled filter design
On 11/09/2018 12:36 PM, bitrex wrote:
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Meant to say "the fact they can work well", rather


Re: fiddled filter design
On Friday, 9 November 2018 17:32:07 UTC, Tom Gardner  wrote:

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

Re: fiddled filter design
On Saturday, November 10, 2018 at 8:49:41 AM UTC+11, snipped-for-privacy@gmail.com wrote:
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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

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