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  • IB vlf patent flash phase

    Wihtes in their patent 6172504 claims that the flash phase cirquit solution is new, but if one looks close one could intrepet the cicuit as a
    bar grap meter! Still the ladder is semi log rather then linear like a LM3914 unit, so i wonder whats so unique whit this patent?
    Not to forget to mention flash ADC's then its just a matter of measuring, AC, DC, phase, current, its just another parameter!

    Has any one looked into 5523690, 6005392 and 5148151 if they are similar to this patent?

    What comes close to my mind is phase counting, could simply be implemented with a pll and a counter, btw that's i suppose every MCU based detektor actually does these days, so using phase traps in HW doesn't seam any new to me... OR?... coments on this patent subject invited.

    Does any one know of a detector that uses phase counting in discrete HW (no MCU counting) and later displaying this like a number or bargraph when phases lock ocurr, angle counting, not a bargraph measuring plain DC.

    Btw again, sometimes looking into many patents
    it seams that a wast majority are recykled stuff
    with somewhat little "holding" content and many
    patents have quite limited strengt! Some barely hold!!

    As Don the tijana Lancaster says, its a bit
    of pain the whole patent issue now days.

    And looking into the enormus production of
    Whites it seams to be a lot of recycled designs,
    a pot here a diode there, well that was rather coarse but 7-10 models of the 6000 DI pro only??

    So what is actually new, does anyone have in-depth knowelege of detector design history? Dave perhaps, you have a interesting OTA patent!
    Im interested in the design history to know
    where different solutions "came new" and "when"
    they went into industry practise in a time scale
    of some sort.

    Reg
    BJ

  • #2
    Patents and the History of Metal Detectors

    The Patent Fiasco

    You're right, the White's flash phase patent is just an application of a flash ADC in measuring phase. Not even phase, either, but the output voltages of an I/Q demodulator. I suspect this little solution is well known amongst radio designers who always want to look at I/Q signals.

    Thus the whole problem with patents. It would be impossible for a company like White's to know about all the prior work that's gone on the field of general radio design. Yet I bet with a few days work (or maybe a few hours) one could find prior art that completely negates their patent.

    I have several patents myself, mostly because my company encourages them for their "patent portfolio". To use as a large club when dealing with other companies. But I suspect that only one or two of my patents would hold up. As an example of all the silliness with patents, Motorola came after one of my chip designs because it infringed on their 1996 patent on a bipolar latch. I found prior art (the exact same circuit, in fact) from 1974 in only 2 hours of searching. That's gotta be embarassing.

    Observation #1: Don Lancaster is almost exactly right: read his "Busting a $650 Patent", good info. Read it 2 or 3 times.

    History of Metal Detectors, Part II

    Part 1 was written by Roy Roberts and published in Western & Eastern Treasures. I have the PDF on Geotech. He did a wonderful job, but his coverage stopped with WWII, just before the hobby industry started. I'd love to collect enough info to write a Part II that covers the hobby years.

    Early pioneers in detectors were Gerhard Fisher, Bob Gardiner (Gardiner Electronics), Bill Mahan (D-Tex), Ken White, and Charles Garrett (others??). All their designs were basic BFO and TR, except I think Gardiner did some early work in VLF and discriminators. I'm told that Dick Hirschi invented the TR/Disc, maybe someone can verify.

    And, of course, the VLF motion disc. was invented around 1976-7 by George Payne. This is still the fundamental technology that's the basis for all current designs. There have been minor variations (filter designs, digital processing, multifrequency) and minor feature additions (notch, tone ID, graphical ID) but no really new innovations in VLF.

    Observation #2: We haven't gone very far in 25 years.

    Some people will point to Minelab as an example of innovation. OK, I agree, their pulse techniques are pretty slick, but I believe some of it has been around for a while. Look at Barringer's patents. Also, the multifrequency detector has been around at least since Westinghouse's 1972 patent.

    Observation #3: Patents are at least good for tracking the history of technological developments.

    Send me info

    This is a good opportunity to solicit info from forum visitors on the history of the metal detecting hobby, particularly the last 50 years. I'd like to write this up before the end of the year. Especially needed are articles (or references) that document historical items. Personal recollections are also invited, but I'd like to be able to verify the details.

    - Carl

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