Sudden Confusion

All that Bracewells novel factorisation of the FFT did (these days now called the Fast Hartley Transform) was to facilitate an easier version of the real data to an equivalent of complex conjugate symmetric transform FFT that electronic engineers seemed to prefer for some reason because it "avoided" using complex numbers directly.

It had all the same properties as the FFT. No-one who knew what they were doing and cared about performance actually used it because faster real to complex conjugate symmetric transforms were already known. See:

It multiplies by a reciprocal then. Or perhaps just substitutes what you would like to have seen for the actual observed signal.

I don't find "algorithms" that explode spectacularly when handling a noisy signal particularly appealing. YMMV

--
Regards,
Martin Brown

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Sure. Analog Devices has been selling this as a - relatively expensive

- off-the-shelf solution for years. I've even pointed people at them here, from time to time.

I can't do the tunablility, but I could phase-lock my solution to any reference frequency you fancy.

Since the distortion you propose to correct by feed-forward is going to be frequency dependent, the orders of magnitude tunability won't be easily coupled to the low distortion specification.

The classic solution was a twin-T filter to notch out the fundamental. Win Hill's "The Art of Electronics" suggests using a a "bridged differentiator filter" which is rather easier to tune and looks to be close to as good in practice. I'm planning on putting one on the board to be shipped to London for my friend there to test. His sound card has had a college education and should be able to make sense of what gets through the notch filter and the subsequent amplifier.

y

I'm neither an idiot or a liar. Being retired does make you something close to a useless fart, but there's not a lot I can do about that at the moment.

-- Bill Sloman, Nijmegen

Did it never occur to you that you were getting older?

--

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

I do, and I don't blame anyone for feeling a little peeved at being made to support such individuals; this is just human nature and everyone (myself included) has had such feeling.

Nevertheless... at least personally I try to remind myself that:

-- Every infuriating story about someone who really is exploiting the system tends to make me forget about the hundreds if not thousands of people who use welfare as it is intended and really do better themselves and, eventually, the community. It throws one's perspective out of whack, and unless we recognize this we can make judgments that those with more objective perspectives would not.

-- I really don't believe it's in human nature to continually take from others without contributing in return. Of those who do, I'm convinced that many of them might actually be mentally ill... and yet unfortunately treatment for mental illness is very difficult to come by if you're destitute, hence the problem becomes perpetual.

I could go on, but I think you get the idea. I have faith in us as a species; there are *very* few truly "bad" people out there.

---Joel

No. It computes an error function and closes a feedback loop onto the FIR filter coefficients, all in the time domain, without transforms. It takes a few iterations, like five typically, to derive a good filter to normalize the step response of a messy TDR system. Without transforms, it's very fast.

The hard part about building a TDR isn't so much the bandwidth, it's getting the step really clean. That's a lot easier to do in software than in hardware.

Or perhaps just substitutes what you

Given that you want to enhance signals that are fading into the noise, or create fast risetimes from a signal lacking the required information, any attemps are doomed to fail, and some failures are more colorful than others. You can't equalize back what ain't there.

The transform methods have a worse problem, in that an FFT can have small or zero lines well within the actual signal bandwidth, even without noise. When you think about it, the FFT/divide is really dumb.

--

John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro   acquisition and simulation

Agreed, but I have a sneaking suspicion that even if your tax rate were, say, 1/10th of your income, there's a good chance your *actual standard of living* wouldn't be significantly different: You'd just be shelling out money directly to pay for, e.g., toll roads, private schools, etc. but at the end of the day your actual disposable income's *purchasing power* might not have changed much.

I could be wrong here; I'm definitely not versed well enough in economic theory to try to make any sort of hard argument about it.

---Joel

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That fact gets impressed on my attention pretty regularly these days. I've just spent the evening at field-hockey practice, and that brings home the point quite emphatically.

Cognitive skills don't decline with age in the same way that muscular strength does.

-- Bill Sloman, Nijmegen

. Taxes

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Bush was a Republican and his wars were idiotic - Republicans find being reminded of this tiresome.

Scarcely permanent. Obama's stimulus spending is a direct result of the bursting of the US house price bubble engineered by your beloved bankers. It's needed to keep the economy out of recession, but only as long as the economy is in recession, There's nothing to suggest that the US economy is going to be stuck in permanent recession (unless the Tea Party gets its hands on the economy) so the stimulus spending is temporary, not permanent.

You don't understand the idea behind stimulus spending, and treat it was something you can understand - Democratic extravagance - but this reflects your mental inadequacies rather than any defect in the Democratic economic program,

Nonsense. 3/4 bankers making ninja loans and 1/4 Bush invading countries that he didn't need to invade and couldn't occupy effectively after he'd invaded them.

The Republican elements in the legislature had an appreciable influence as well.

=A0Oh,

An interesting claim, but not supported by a single number, or any reference to any numbers. The Occupy Movement has a whole slew of numbers supporting their point of view. It's kind of difficult to see how the 99% can have seen their total compensation tripled since Regan came to power, but since we know how fantastically numerate you are (with the emphasis on the fantasy) no doubt we will shortly be entertained with a moving example of mathematical prestidigitation.

Government made? You've been making that claim for years, and you should have noticed by now that it isn't true.

ity_reinv.html

That does seem to be what you want the economy to do. Abandon all the Kenysian stimulus spending which is all that is keeping your economy out of recession and have a nice little rerun of the 1937 recession, caused by people who thought as your do and unfortunately had more influence.

-- Bill Sloman, Nijmegen

f

The whole "significance of the difference" is that you are a sucker for inflammatory anecdotes in the right-wing press.

The Jukes and the Kallikaks never actually existed, but they get re- invented at regular intervals to justify cheapskate right-wing social policies.

-- Bill Sloman, Nijmegen

The day that Bill knows more than demagoguery, prejudice, propaganda, and bullshite about economics they will give me a Nobel Prize for what i = know.

?;-)

Nonsense. Perhaps you forget the gas tax.

Of course you are. Lefties always are. Remember, the government has nothing that it hasn't taken from someone else by force and it charges a commission.

In very many senses the Federal Reserve is a GSE much like Fannie and =46reedie. See also FDIC; tax dollars backing private banks (to be fair = the banks pay some as well, but far below what real insurers would charge).

?-)

Sure, the government has a "commission," but private industry needs to make a profit. So in effect both are "inefficient," just in different manners, right?

(Not that I'd ever suggest private industry *shouldn't* make a profit; this is completely essential to the economy.)

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When inflation gets past 10% per annum, it proves to be one tough boojum to put back in the box. You, John, should remember double digit = inflation from the late 1960s through the late 1970s.

?-]

The day that Bill knows more than demagoguery, prejudice, propaganda, and bullshite about economics they will give me a Nobel Prize for what i know.

?;-) ________________________________________________-

Why would you even want one???

members of

the

support

=20

=20

I so dearly wish the ratio were 100:1 for honest folk having a bad time, perhaps for private charity it is not too far from that. But for govmonk run programs it tends to run at the reverse ratio, one honest person to

100 money grubbing willful neer-do-wells. And that is exactly why government should NOT be in the charity business. =20

Job training similar to WPA is ok, construction is something that must be done on site (pretty much). It is honest work though tiring and pays ok. Picking crops is honest work but doesn't pay decently. Guess what jobs the go begging to immigrants? What jobs do the whiners want? Guess why.

some

=20

=20

Nobody is. It is just the PHds that think they are. Their track record for being proven wrong by history should be sufficient to eliminate the study, if not advanced degrees, altogether.

?-)

commission.

No.

Different causes for the differences entirely.

^^^^^ stuff ^^^^^ minutes

Had to correct this one. There is no way you, John, are that less able than i. Bill seems to be another matter.

Special translation for Bill: Shut up and build it, today. Measure it today too. Rent/lease some test equipment if needed.

?-)