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More useless JL noise. Of course there will be tons more computer screens than oscilloscopes. You only need to do a few measurements with an oscillo scope, but there are innumerable design tasks which require a computer. He ck, JL himself talks about simulating rather than calculating which require s MUCH more computer time.

JL's typical dismissal of things he doesn't understand.

Rick C.

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gnuarm.deletethisbit
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If you think these don't come from JL then you haven't been paying attention.

Rick C.

Reply to
gnuarm.deletethisbit

I generally /don't/ pay any attention to pointless attacks, no matter who they are from. In this thread, there is no doubt that Bill came out with an unjustified, off-topic attack on John. And unlike some of the posters here, I think Bill is rational enough that he /might/ be influenced by what people write.

I said "I am not suggesting these attacks and insults come from John Larkin". Equally, I am not suggesting that he does /not/ make such attacks.

All I am saying is this group would be nicer with a few less of them - from everyone.

Reply to
David Brown

Yes, for sure, but unmoderated public forums attract people who want to shriek, or plainly unbalanced types, and the impersonal nature of the internet makes for bad dynamics. Things spin out of control as they wouldn't in real life.

Twitter and such could easily delete foul and abusive posts, but they don't, because they make money off them.

I can be a little ironic and challenging, but that is sort of in the mode of classic debate. I don't swear, or call people idiots or worse. I don't denegrate people for being less intelligent than they might be (people can't help how they were born) or for making simple mistakes.

Sloman insults everyone, in his tedious third person mode. He is a sad case, to be pitied and ignored rather than argued with. It's unfortunate that an intelligent person isn't researching and posting on topic... there is so much out there to explore. He should get some test equipment and do something more rewarding.

The gnuguy and a couple others want to turn everything into a personal challenge; it's better to ignore them too.

I am just now re-reading Barbara Tuchman's books The Proud Tower and The Guns of August, about the times before and during WWI. Great stuff. In France, the Dreyfus Affair was a bigger social and political upheaval than anything we have here now - lots of fake news and bombings and shootings and old friends never speaking again - and all they had in Paris was 25 newspapers to fan public passions.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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John Larkin

They are less annoying if you don't read them.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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John Larkin

Where was that? We should contact their placement office. Some schools still do real electronics, but the resumes I get from students are almost always about programming. Everybody wants to program FPGAs for some reason.

I built a few 6800 products, and wrote a preeemptive RTOS for that chip, which wasn't easy. It wouldn't even push the index register onto the stack.

My high school counsellor chose for me. She said "I can get you a scholarship to Tulane" and I said OK. That worked out; I learned the basics and did the fun stuff in outside jobs.

It takes a semister or two to really get into this stuff. I don't have the time or teaching skills to get them up to speed; maybe just enough to get them interested. I should buy a bunch of these and hand them out:

formatting link

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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John Larkin

Yup, great stuff. I also recommend anything by Ben Macintyre or Giles Milton--I just finished "Churchill's Ministry of Ungentlemanly Warfare", and "Operation Mincemeat" is hysterically funny.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Phil Hobbs

Of course it isn't. Direct Digital Synthesis chips make it easy.

Chapter 7.1.9C of AOE3 explicitly recommends the Analog Devices AD9854 for the job. Digikey has got it in stock. It's not cheap, but slower parts could well be cheaper.

--
Bill Sloman, Sydney
Reply to
bill.sloman

Looks like I made mistakes: 112 benches, only a 200MHz MSO: In total there are 112 benches kitted out with the following: 2 x TTi EL302R PSU (Linear regulation: 0-30V/2A) 1 x TTi EL155R PSU (Linear regulation: 0-15V/5A) 1 x Mixed Signal Oscilloscope (200MHz, four analogue/16 digital channels) 1 x Hameg HMC8012 Digital Multimeter 1 x Arbitrary Waveform Generator (50MHz, Dual channel) 1 x High spec PC 2 x Dell U2715H 27? QHD Monitor (2560 x 1440 resolution) 1 x Saleae Logic Pro 8 Logic Analyser

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I only wrote a cooperative RTOS, and had forgotten that irritation. I never had the chance to use a 6809.

What /really/ appalled me was the inflexibility of the z80s ix and iy registers. To do just about anything with them you had to transfer them to/from the 8080s registers, one byte at a time.

Scholarships were (are?) rare here; there was less need for them.

I didn't bother with sponsorship; it wasn't so necessary over here, back then. Of the people that did have MoD or Post Office sponsorships, all but one got first class degrees, and all but one of the people that got first class degrees had sponsorships. That made me respect the Post Office / MoD selection process :)

It is a delicate balance between pushing them and encouraging them to pull. Each kid is different and needs different stimuli/feedback.

With my daughter a little push was necessary to overcome her initial reticence, and then she pulled.

Reply to
Tom Gardner

Dang, looks like another trip to the book donation depot, to make room for more.

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

Doing good phase shifters over a very wide fractional bandwidth is hard, at least if you really want constant 0 and 90 degree shifts.

The usual RC baseband phase shifter is actually a phase sequence filter whose phase linearity isn't that great IIRC, so although you can do SSB things it isn't really I/Q.

There are several methods to get real I & Q, of course. For instance:

  1. Mix up to some out-of-band frequency, filter, mix down with a shifted LO. The filter is a problem for wide bandwidths, because it needs to cut off very sharply near the carrier without introducing gross group delay.
  2. Digitize fast, do a Hilbert transform, and then convert back to analogue. The Hilbert kernel isn't too well-behaved for wideband signals, unfortunately--it's a convolution with 1/(pi t), which has an infinite spike and infinite area in the tails. You really need both the spike and the tails to cancel out accurately, which is harder to arrange with wideband signals. Transform methods also introduce a time delay of many samples.
  3. Build a linear-phase bandpass filter whose phase asymptote goes through (0 Hz, pi/2 radians) and match it with a normal Bessel filter with the same delay.

Got something new up your sleeve? Something Weaverish maybe? If one used a Weaver scheme with two back ends, producing USB and LSB, one could probably make a decent I/Q phase shifter by adding and subtracting them. It would take a lot of parts, of course, but maybe not as many as a 500:1 phase sequence filter with decent accuracy.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Phil Hobbs

Montana State turns out great people, and so does CU Boulder.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

What John Larkin had posted (about DecadentLinuxUser ..) was

" You certainly "work in electronics." But do you design electronics?"

which struck me as insulting and unjustified.

My reaction strikes me as perfectly justifiable, and - in the context - on-topic

"John Larkin works in electronics, and thinks he designs electronics, but what he posts suggests that he actually evolves electronics.

Since John Larkin also seems to believe in "intelligent design" as opposed to Darwinian Evolution, he may not see the inconsistency."

The second line may exaggerate John Larkin's attitude to evolution, but he has posted some quite silly stuff on the subject, and I think it works as a comic elaboration.

Not this particular string of text.

John Larkin posts more than anybody else who posts here, and he is frequently mean, spiteful, and remarkably thin-skinned, which does set an unfortunate tone.

--
Bill Sloman, Sydney
Reply to
bill.sloman

David Brown wrote in news:pnthnm$76u$1@dont- email.me:

And again, despite knowing the history where it is apparently OK when JL chooses to do that, you jab at Bill for simply returning the favor.

Not to mention the fact that he is correct about JL's behavior.

Reply to
DecadentLinuxUserNumeroUno

John Larkin wrote in news: snipped-for-privacy@4ax.com:

Like you accusing everyone of not "doing" electronics or any number of other JL mouthed jab's at other posters.

What is good for the gander is good for the goose.

Reply to
DecadentLinuxUserNumeroUno

John Larkin wrote in news: snipped-for-privacy@4ax.com:

Dishes it out, yet cannot take it. Who'd have thunk it?

Reply to
DecadentLinuxUserNumeroUno

snipped-for-privacy@ieee.org wrote in news: snipped-for-privacy@googlegroups.com:

And that is the kind way of putting it.

Reply to
DecadentLinuxUserNumeroUno

I was staying with a friend in Juneau, Alaska. I wrote the REX RTOS in longhand and mailed sheets back every day to the guys in New Orleans, who punched cards and eventually assembled it. It had one bug.

Tulane then cost $1200 a year, so it was possible to work your way through college. My parents would have paid the tuition too, but they were fairly poor, which probably contributed to me getting the scholarship. I also took the SAT tests six times, junior and senior year in high school, and got pretty good at it. Test-taking is a skill of its own.

OK, just ordered six copies from Amazon.

I think kids have to learn electronics early, to develop instincts. The math and stuff can come later.

--
John Larkin         Highland Technology, Inc 
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John Larkin

Williams has tables for 1000:1 all-pass shifters better than 1 degree.

Just the SSB phasing-method allpass. One analog input makes two outputs that squirm in phase vs frequency, but stay 90 degrees apart. My customer will work at one frequency, and I can encourage (force) him to do a vector rotation on the i/q baseband waveforms to rotate the zero-degree output into alignment at his frequency. He's going to do that anyhow, to adjust for cables and whatever.

Something like page 15 of this:

yu1lm.qrpradio.com/AF%20ALL-PASS%20NETWORK-YU1LM.pdf

but maybe a few more sections. If that gets too twichy, I could do two separate ones, each maybe 30:1 freq range, and switch between them.

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

But electromagnetics, control theory, s&s are often now electives in an EE degree program.

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

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