I'm writing a paper on the history and theory of Digital Delay Generators. So far, the HP 5359A seems to be the first "modern architecture" DDG I know of. HP did another, possible older, unit based on a triggered crystal oscillator, if you can imagine such a thing.
Does anybody have any idea of who did the first DDGs? There's a good chance it was in some physics lab, maybe written up in one of the physics journals.
I know that BNC and LeCroy did DDGs in the 1970's sort of time frame.
Physicists were into this kind of stuff fairly early on. The Wilkinson time-interval digitiser is pretty old.
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may give you a look into that literature.
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might include a decent review of the literature, which is to say it would have done if I'd refereed the article. You could buy it for around $30 or get a friendly academic to download it for you.
That's a TDC, not a DDG. And he somehow neglected to mention my technique.
That one looks like a specific, recent application. I'm more interested in ancient history.
It's downright unscientific that scientific papers are only available for sizable chunks of cash, and that a few companies monopolize that trade. It takes money to, usually, find out the the paper is mostly worthless.
Actually, you are right about that problem. It wasn't always as bad as it is, now. But Elsevier has purchased a number of the older publications and they have a very profit-minded approach, sadly. Morgan Kaufman which is another publisher is also, for example, ultiamtely owned by Elsevier. So not only the publications, but the publishers, have been consolidated to a level unseen earlier.
In regards to journal subscriptions themselves, and not other issues, it seems to be at least, if not other things, that Elsevier is singled out as being uniquely expensive. Policies may mention "high cost" as a general problem, but will name Elsevier by name in their policy, as well, and no one else. So that makes me think that Elsevier is a special problem here.
The response from scientists has been spotty, but strong. For example, Elsevier has been singled out by Stanford, the University of California, Harvard University and Duke University (to my immediate recollection) to discontinue their Elseview journal subscriptions.
Many scientists I know also refuse to peer-review Elsevier papers. Free public access to science papers is vital and Elsevier stands fairly in a uniquely detrimental position, it seems. However, some publications promise to release to the general public after six months, and that's at least some progress on this point.
Also, I've NEVER had any trouble getting a full copy of the article from the scientists who are authors on the paper. Occasional delays, yes. But no refusals, ever. Most scientists, I guess, are able to retain the right to send copies of what they write to people, directly. Also, many scientists keep a pre-publication copy directly on their web sites for download. Usually, that is very, very close to the published article.
The response by many scientists hasn't just been about high costs, but also about the peer-review process and open, public access to science knowledge -- which is almost universally held dear to the heart, scientists being especially concerned about this, like few are.
Several scientists I know have put their foot down, so to speak, and simply refuse to review for, submit to, or subscribe to journals that are not providing open access after 6 months (as mentioned above.) This means that scientists are refusing to even participate in peer-review of papers from Elsevier or to submit them for review through their journals. The personal policy by individual scientists like those I'm referring to applies to _any_ publisher, though, and not just Elsevier. At that level, it is simply about fair licencing and open access to scientists' results. 6 months is enough time, many seem to think.
So does the f...ing IEEE. I've dumped out of that membership completely. If I can't find a paper free I'll just go to the ASU engineering library since I'm an alumnus.
[snip]
...Jim Thompson
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| James E.Thompson, P.E. | mens |
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Liberalism is a persistent vegetative state
It ought to review the literature, which usually takes you back twenty or thirty years. You then get hold ofthe oldest relevant looking paper mentioned, and have a look at it's review of the literature. If you can get at a university library that holds the relevant journals, you can get a long way in a couple of hours
All true. This particular paper was published by the British Institute of Physics, which is a not-for-profit organisation If you can log in from an institution that subscribes to journal, you can get the paper for free. My wife can do this for me, if I ask her nicely. I'll e-mail you a copy if I manage to ask her nicely enough, and if the review of the literature is deep enough to be of interest to you.
If you have a university near you, you might try checking its library. Talk to the reference librarian, if they have one. I can't speak for any other university but at mine (Colorado State, Fort Collins, CO), if you are physically in the library, you have complete access to all the electronic journals and research databases, even if you have no affiliation with the university. (If you're a student, staff, faculty or emeritus faculty, you can access everything remotely as well.)
Ask the librarian if they subscribe to the "Web of Science" database. If they do, have them show you how to use it. WoS is a searchable database of papers published in almost all scientific or technical journals since 1900(?). Little to no conference coverage, though.
I have all the RadLab books, and I've been looking through them too. I haven't seen what I call a DDG, but they get close. They just didn't have much in the way of digital counters. I'll cite this case, too.
My DDG's, as you probably recall, use an LC "start oscillator" that's started with the input trigger and clocks the coarse down-counters, with the usual final analog ramp to interpolate between clock ticks. The LC is phase-locked to a continuous-running XO for longterm accuracy.
The 5359A used an ecl delay-line "stop oscillator" that ran continuously, phase-locked to an XO. At trigger time, they quenched it briefly and started it again, and used that for the digital delay. It was, after that, again phase-locked to the crystal using a clever heterodyne technique.
It's hard enough to start a crystal, but it's even harder to stop it. The danged things rattle for a long time. An LC can be mostly killed in under one cycle.
Somewhere I have a $2000 electro-acoustic delay line, a couple of hundred usec. It rings like a bell for milliseconds.
The question is how to prevent search engines from coming up with all those IOP and whatnot links where you only get an abstract that dopesn't even contain your search phrases. It's annoying.
Guilty. I have refused.
Peer review is a pretty lame excuse. Reviewers generally do not get paid for that. I've done it a few times.
John, if you want to historic stuff just contact them:
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If you aren't their competitor they might even be willing to point out some retirees. Then invite one to Zeitgeist and have a long chat.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
In those days people where free to explore and implement the most outlandish techniques. Nowadays one already receives scoffs when merely presenting the idea of the old Q-multiplier. Younger engineers consider such stuff wacky.
Ok, getting off my soap box now.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
For mechanical lines you might want to explore the old Collins Radio Company, way before it was acquired by Rockwell in the early 70's. They were heavily into mechanical resonators starting in the 50's. Repairing those was like taking apart a car engine into all its pieces. I had enough after one such session.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
They still make them. You just machine a bunch of lumps into a metal rod and hang transducers on the ends. Hard to beat for narrowband frequency-domain stuff, although DSP and such are getting cheap.
The construction method wasn't, ahem, all that durable. Foam crumbles, paper soaks moisture and so on. Here is the reason why I preferably don't want to repair another one:
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Yes, DSP can be had for around four bucks. But even today clients are often amazed when an analog solution is complete and they measure the supply current. Tap, tap, tap ... hmm, maybe the needle is stuck.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Peer review isn't an excuse for much of anything, really. The point I was making is that the publishers of the periodicals want to "make some money." It's my feeling that this is a reasoned request, but that six months rights is all they should have. That's long enough that other universities/staff who want to keep absolutely current on what is going on in a field will have to pay something for that faster access, but short enough that those of us who are essentially outside of some specific field can get public access in a reasonable time. I think the periodicals should be satisfied with six months protection, no more. Less would be even better from my perspective, but the reality is also that I just write the authors and ask and I've never been turned down... not once. So even if I want something that is hot off the press I can get it for free. Never failed.
"John Larkin" wrote in = message news: snipped-for-privacy@4ax.com...
message news: snipped-for-privacy@4ax.com...
Since Jack Kilby didn't file his patent for the IC until Feb 6, 1959, I assume all the dividers in the HP instrument were made with discrete transistors.
I took a look at _Electronic Measurements, 2nd ed._ by Terman and Pettit (1952). The preface says that generation of time delays is one section that they have added on a subject that was "nonexistent... or were = prehaps only scientific curiousities" at the time of their first edition (1935). = =20
The techniques they show all seem to be based on one-shots or linear = analog=20 ramps, eg. from a Miller integrator. At the end they cite some "other = schemes" from "the literature": "Electronic Time Measurements" from vol 20 of the Rad Lab series and Some Precision Circuit Techniques Used in Waveform Generation and Time Measurement, Rev. of Sci. Instruments, vol 17, p. 396 (Oct. 1946). Britton Chance, "Time Modulation", Proc. IRE vol 35, p. 1039, Oct 1947.
You might want to take a look at this book: Author: Oliver, Bernard M., 1916- =20 Added author: Cage, John M. =20 Title: Electronic Measurements and Instrumentation. Edited by = Bernard M. Oliver [and] John M. Cage. =20 Imprint: New York, Mc-Graw-Hill [1971] =20 Physical Description: xviii, 729 p. illus. 24 cm. =20 =20 As I recall most of the chapters were written by HP people; but I don't know if there is anything on time delay generation.
--=20 Regards, Howard snipped-for-privacy@ix.netcom.com
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