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MSimon
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Postby MSimon » Tue May 26, 2009 10:10 pm

I prefer design where I can work out roughly what a circuit will do before I build it, and before I simulate.


Why Tom, you don't trust simulations from the get go? I'm shocked.
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TallDave
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Postby TallDave » Tue May 26, 2009 10:29 pm

I believe you think that because some parameters in GCMs are determined stochastically (from data sets independent from, indeed of a completely different kind from the global temperature that is being predicted) therefore the model has no more validity than an arbitrary stochastic model.


I'm not sure that matters one way or the other. If GCMs were better at predicting than a naive forecast, we could say "OK, you have a working physical model here." But they don't. And the bar for a physical model is so much higher than a stochastic forecast that it is somewhat shocking anyone could claim a GCM was a working example of the former.

The IPCC is a scientific organisation set up to advise politicians.


The IPCC is set up by UN politicians, not just for them. Those politicians then pick the scientists (who, shockingly enough, tend to have views that support the politicians' agenda). This self-licking ice cream cone creates huge problems of credibility. The UN has lots of obvious problems like this, such as when Cuba, Syria or Sudan sit on the Human Rights Commission.

As for influence, getting dozens of countries to agree to take economically damaging actions is definitely pretty influential.

wikipedia wrote:The IPCC Panel is composed of representatives appointed by governments and organizations. Participation of delegates with appropriate expertise is encouraged. Plenary sessions of the IPCC and IPCC Working Groups are held at the level of government representatives



Crertainly none of the anti-AGW vignettes posted here seem convincing when examined carefully.


They seem much much more convincing than the pro-AGW evidence, much of which cannot even be examined because the authors won't release it (ABS#2?).

Of course, replying to blog simplifications and slur by more blog simplifications and slur does not get us very far. To survey properly the relevant literature and come to a truly informed opinion takes time. But if you don't believe the scientific consensus then either you remain in a state of uncertainty, or you do this work.


I've done enough of the work to know the AGW case is very weak. It's a very informed opinion. I've read far more pro-AGW studies than anti-AGW. A large amount of questionable one-sided data and flawed assumptions is not better or more convincing than a small amount. Skepticism must be the rule, not the exception.

Climate science has a huge self-selection problem, just like journalism's liberal skew problem. Many people become interested in climate science via environmental activism (which in turn produces more funding for climate science) so you get "consensus" on ideas that appeal to environmentalist activists.

As for scientific proof. It is not a matter of null hypothesis vs something complex. Climate exists, CO2 clearly influences climate. the scientific question is how much,


Yes it is. The null hypothesis is that man's CO2 emissions are not creating a huge problem. AGW advocates have to prove that they are. If they can prove that, there are all sorts of actions that would logically follow. If they can't, we should do nothing.

Assuming that it is zero when that is clearly not true is invalid.


No, assuming a problem exists without proof is invalid. You can't just reframe the issue as "does CO2 influence climate."

I don't believe you would be so set against this if it were not for the political ramifications.


Of course I wouldn't! That's the whole point. Spending trillions of dollars without proof of an actual problem is a very bad idea.

For example, let's pretend the "Steady State" theory in cosmology had serious policy implications requiring trillions of dollars. Before Hubble, there was a very strong scientific consensus that Steady State was the right theory. I bet you could have gotten "99%" as an estimate of the likelihood. That's why this AGW "consensus" business is so dangerous.
Last edited by TallDave on Tue May 26, 2009 11:12 pm, edited 15 times in total.

ravingdave
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Postby ravingdave » Tue May 26, 2009 10:30 pm

tomclarke wrote:raingdave -

Yes - 2$ is cheap, now £1.30.

I have virtually given up using assembler (and particularly detested 80xx assembler the few times I met it). Do you have enough ROM/RAM resources for a compiler? Simon would probably argue you use FORTH - perhaps better than assembler. Don't forget if resources are limited that you always end up using twice as much ROM as you initially expect :)


I believe TI provides a PC compatible cross compiler, but I prefer assembly. I like the fact that there is not anything it can't do. Besides, when learning a new architecture, it's easier to see whats going on than it is in a higher level language. Nowadays, ram and rom aren't much of a problem, but when I first started programing microprocessors, they were a big problem. I managed to write a time clock program (including day of the week ) using only 256 bytes of rom, and using no RAM whatsoever ( In CDP 1802 machine code.) It made for a very tidy 4 chip design back in 1982 !

Such a thing would not be possible in "C" or "Forth" etc.


tomclarke wrote:There are current-mode op-amps now with GHz bandwidth but I am not good enough at RF design to use them without hassle. (I could follow app notes with pcb layouts, given a spectrum analyser and time I could sort out problems, but I will avoid it if I can!). I prefer design where I can work out roughly what a circuit will do before I build it, and before I simulate. It is partly down to experience - I used not to be able to predict what designs up to 100kHz would do without building them. And sometimes they still surprise me.

Tom


Yeah, analog designs can be a pain in the bum. :) If I have to use high frequency analog circuits, I try to find something someone else has already worked the bugs out of and adapt it to whatever i'm trying to do. It also helps to read what Robert Pease has to say over at "Electronic Design" . That guy is D*mn smart ! He is an analog genius! (BSEE from MIT in 1961 !)


On a different subject, I'm thinking you should be worrying about something else a lot more than Global Warming.

http://www.youtube.com/watch?v=6-3X5hIF ... r_embedded




David

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Eh?

Postby TDPerk » Wed May 27, 2009 2:51 am

Such a thing would not be possible in "C" or "Forth" etc.


The several times I've used it lead me to believe it is an extraordinarily tidy language, one only assembly can beat. I suppose 256 bytes of ROM might in some circumstances be better than 196 of ROM and 4 of RAM--what I expect that clock would map to in FORTH--but not usually I think.

But if you are stressed enough--I just mean operating envelope corner--every case is special.

Yours, TDP, ml, msl, & pfpp
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TDPerk
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Err...

Postby TDPerk » Wed May 27, 2009 2:53 am

"It made for a very tidy 4 chip design back in 1982 ! "

Err.

I inquire too late, one was a uC, correct?

Yours, TDP, ml, msl, & pfpp
molon labe

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MSimon
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Postby MSimon » Wed May 27, 2009 2:57 am

The 1802 was long of tooth in 1982. Although IIRC it was the only CMOS uP available at that time. Almost everything else was NMOS.

BTW the 1802 was excellent as a FORTH processor.
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ravingdave
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Re: Err...

Postby ravingdave » Wed May 27, 2009 5:28 am

TDPerk wrote:"It made for a very tidy 4 chip design back in 1982 ! "

Err.

I inquire too late, one was a uC, correct?

Yours, TDP, ml, msl, & pfpp


Yup. RCA CDP1802. It had 16 general purpose registers in it which is why I could get by without any ram. The other chips were 2716 eprom, and two 74ls373s to drive the seven segment display.



David

ravingdave
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Postby ravingdave » Wed May 27, 2009 5:44 am

MSimon wrote:The 1802 was long of tooth in 1982. Although IIRC it was the only CMOS uP available at that time. Almost everything else was NMOS.

BTW the 1802 was excellent as a FORTH processor.


That's the first microprocessor that I learned how to build circuits with, plus it didn't require much in the way of support circuitry. A Z80, or a 6502 or even a 6800 type processor requires ram, rom, data latches, buffers, address decoders etc to get it to do anything useful. An 1802 could do the job with just one rom and two data latches!

I was drawing out the printed circuit board design by hand, and I wanted the smallest chip count I could get ! :) We processed the boards with UV light through an optical mask and used ferric chloride to etch them. The fewer the traces we had, the less trouble we had to deal with caused by bad etching or bad exposures.

I miss the old 1802, but we've got a lot better stuff nowadays. (CC1111)


David

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Postby MSimon » Wed May 27, 2009 7:45 am

ravingdave wrote:
MSimon wrote:The 1802 was long of tooth in 1982. Although IIRC it was the only CMOS uP available at that time. Almost everything else was NMOS.

BTW the 1802 was excellent as a FORTH processor.


That's the first microprocessor that I learned how to build circuits with, plus it didn't require much in the way of support circuitry. A Z80, or a 6502 or even a 6800 type processor requires ram, rom, data latches, buffers, address decoders etc to get it to do anything useful. An 1802 could do the job with just one rom and two data latches!

I was drawing out the printed circuit board design by hand, and I wanted the smallest chip count I could get ! :) We processed the boards with UV light through an optical mask and used ferric chloride to etch them. The fewer the traces we had, the less trouble we had to deal with caused by bad etching or bad exposures.

I miss the old 1802, but we've got a lot better stuff nowadays. (CC1111)


David


Did you ever look at what Sinclair did with the Z-80? He used the address lines to decode the keyboard. It was very slick. I may even have my old Sinclair in the junk some where.

With only 256 bytes of ROM you could have used some of the spare address lines for the latches. Although IIRC DRAM refresh might have interfered with that.

And yeah. I used to make boards myself. I think I dumped my last packet of FeCl a year or two ago. I even made my own bubble etcher.

Kids these days don't know what fun is.
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IntLibber
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Postby IntLibber » Wed May 27, 2009 8:15 am

tomclarke wrote:How to recognise SBS

Here is Morner's paper - a classic example of SBS:
http://www.junkscience.com/jan04/nils-morner_1.pdf

He says:
(1) observational data show sea level not rising over last Century
(2) IPCC got it wrong

You can detect the likelihood of SBS from the fact that more than half of his paper is rubbishing of IPCC based on selective quotation etc.

Check out the papers citations (from a respectable citation database indexed on the original paper, not junkscience). You immediately discover the team analysing the satellite data that Morner quotes, horrified at Morner's naive use of the data.

It turns out that (unlike everyone else in the field) he uses RAW satellite data instead of carefully checking for bias etc. Why is this no good? There are two major biasses is the data:
(1) progressive error due to altimeter degradation
(2) a step error when the satellite was switched to the backup altimeter

These effects have been carefully checked and cross-validated by the groups familiar with the satellite. After the necessary processing for these errors the resulting time sequence shows linear rise in sea levels.

The group dealing with the satellite data were very surprised that anyone would draw conclusions from raw data without first checking for necessary corrections etc. But in this case Morner clearly has an agenda which is not that of a scientist trying to get to the truth,

Best wishes, Tom


Funny, I thought you took anything the UN's "scientific panels" as the be all, end all of scientific truth? Morner headed the UN intergovernmental panel on sea level change, so if your blind faith in the IPCC is any indication, you should be accepting Morners statements as gospel truth.

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Postby MSimon » Wed May 27, 2009 11:54 am

IntLibber wrote:Funny, I thought you took anything the UN's "scientific panels" as the be all, end all of scientific truth? Morner headed the UN intergovernmental panel on sea level change, so if your blind faith in the IPCC is any indication, you should be accepting Morners statements as gospel truth.


Well isn't that interesting.

Tom,

I have had some experience consulting on radar altimeters (weapons including nukes). Do you have a link to the papers showing bias corrections? I'd really like to have a go at them now that I find Prof. Morner was part of the IPCC. When you first rubbished him I thought you may have had a point. Now it looks like it may be another case of adjusting for result and not error.

Of course without access to the data and an inclination to massage it I can't be sure of their result but I can check for obvious misinterpretation.

I'd be glad to spend an hour or two going over the corrections. It would bring back fond memories of some of my work on JDAMs. I was helping a really sharp RF guy and his son who worked together at a defense contractor. They were Christians of a rather unusual sort. They didn't celebrate Easter. They celebrated Passover.

Those devices can be really accurate since they work on the principle of frequency difference which can be measured quite accurately. In addition the devices I worked on were FM so they locked on to the strongest signal. Interesting work if you can get it.

I was actually hired to fix a problem with a PLL in a radio. It had stumped their guys for 6 months. It only stumped me for a month. It turned out their phase detector was double pulsing due to some sharp waveform edges to the 7474 phase detector. They had changed the board layout and a circuit that once worked stopped working (too much phase jitter). It turned out the old board had a bit of coax feeding the 7474 clock. About an inch or inch and a half. A couple of pF. Just enough to round the pulse edges and prevent double pulsing.

I had thought it was a bypass problem and had added bypass caps everywhere. When I got done trying that the board looked like it had a disease. ;-) Then I put my finger in the right place and - it worked. The rest of course was obvious.

Which just goes to show that making assumptions can get you in a lot of trouble. I was gratified though. Their sharp cookies couldn't figure it out at all.
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tomclarke
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Postby tomclarke » Wed May 27, 2009 1:58 pm

Quote:
I prefer design where I can work out roughly what a circuit will do before I build it, and before I simulate.


Why Tom, you don't trust simulations from the get go? I'm shocked.


I don't feel I understand design properly unless I can do a paper design and have a good idea of how it will work. At most this needs a calculator.

That means that with Polywell I would be totally in the dark!

Of course, sometimes you just have to experiment and see, but the more you can work out from first principles the better the design because with a smaller design space you can optimise better.

The thing about simulations is that they don't give you much insight into what are the underlying relationships in the design. Still - they are quicker than building :).

Best wishes, Tom

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Postby tomclarke » Wed May 27, 2009 2:34 pm

Simon -

Here is an open access version of the comment on Morner:
http://www.imedea.uib.es/goifis/OTROS/V ... e_2007.pdf

Also, Morner commented on the comment. Interesting but not very substantial and I can't find open access version yet.

At around the same time Morner wrote a paper claiming that sea level around Maldives used to be higher than now and is currently not increasing.

This also attracted a "we think you are very wrong" comment from a (different) group of people. Morner also wrote a comment on their comment.

I have these PDFs but can't find open copies.

You would have thought, would you not, that whether or not sea level has been rising the last 20 years ought to be a matter of public record - and determinable beyond doubt.

Best wishes, Tom

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Postby tomclarke » Wed May 27, 2009 2:48 pm

I was actually hired to fix a problem with a PLL in a radio. It had stumped their guys for 6 months. It only stumped me for a month. It turned out their phase detector was double pulsing due to some sharp waveform edges to the 7474 phase detector. They had changed the board layout and a circuit that once worked stopped working (too much phase jitter). It turned out the old board had a bit of coax feeding the 7474 clock. About an inch or inch and a half. A couple of pF. Just enough to round the pulse edges and prevent double pulsing.

I had thought it was a bypass problem and had added bypass caps everywhere. When I got done trying that the board looked like it had a disease. ;-) Then I put my finger in the right place and - it worked. The rest of course was obvious.


Yes - fingers are very useful for anything above 50kHz. I would have thought board supply noise as you, though if it was 7474 double-clocking a good scope might be enough to see a possibly ringing clock signal? I guess it would not be obvious to see since digital edges always look horrible and difficult anyway to separate signal and ground bounce.

I am paranoid about digital noise and v careful about supplies & clocks - you save a lot more time over-engineering to begin with. I am also v paranoid about metastability on asynch signals! I once used 74F series flip-flops purely because I wanted the f-f time constants to be as low as possible to reduce MTBF. I only had time for one synchronising flip-flop and it was a fast clock.

Best wishes, Tom

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Postby tomclarke » Wed May 27, 2009 3:19 pm

On the morner issue:

Here is an (open access copy) of paper on sea-level rise. It does seem that the sea is rising! And these people also disagree with Morner's conclusions.
http://timesonline.typepad.com/times_to ... cument.pdf

You can find blogs claiming that because antarctic precipitation is higher when the atmosphere is warmer this will be more important than melting and therefore mean a sea-level fall by 2200! But I have not found serious analysis of this hypothesis.

Best wishes, Tom


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