Query: Interest in clock synthesizer module --useful for stabilizing PC timekeeping (among other things) - NTP

This is a discussion on Query: Interest in clock synthesizer module --useful for stabilizing PC timekeeping (among other things) - NTP ; I'm working on a project for TAPR ( http://www.tapr.org ) that might be of interest to the timekeeping community. It's a very simple clock synthesizer called the "Clock-Block" that accepts a reference input in the roughly 2-50MHz range and generates ...

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Thread: Query: Interest in clock synthesizer module --useful for stabilizing PC timekeeping (among other things)

  1. Query: Interest in clock synthesizer module --useful for stabilizing PC timekeeping (among other things)

    I'm working on a project for TAPR (http://www.tapr.org) that might be of
    interest to the timekeeping community.

    It's a very simple clock synthesizer called the "Clock-Block" that
    accepts a reference input in the roughly 2-50MHz range and generates an
    output in the 5-250MHz range, programmable by a series of jumpers or
    switches.

    My primary inspiration for designing this circuit was Poul-Henning
    Kemp's suggestion that it would work nicely to replace the crystal
    oscillator on a PC to allow much more stable timekeeping. For example,
    it can generate 14.318182MHz or 33.333333MHz from a GPS disciplined
    oscillator or other stable reference. A PC with a Clock-Block and
    external reference should be able to keep *very* good NTP time.

    But there are likely to be other interesting uses as well; one I'm
    considering is replacing the clock in a sound card to get precise sample
    rates.

    There's information about my prototype (and a picture) at
    http://www.febo.com/time-freq/hardware/ICS525/

    The prototype works well and we are now ready to move to production.
    Before we do that, I'd like to get a sense of the interest level (if
    any), and in particular whether there's enough demand to warrant an
    semi-kit or assembled version instead of TAPR's usual bag o' parts.

    As a kit, the Clock-Block would be quite inexpensive; we haven't
    finalized the BOM yet but I believe TAPR would be able to sell it for
    well under $50.

    However, assembly may be problematic for some folks, because the
    synthesizer chip is a "SSOP" surface mount package with about 0.5mm lead
    pitch. I've had no trouble putting down these chips using a microscope
    and small iron but not everyone may be willing to take on that challenge.

    I am guessing that given the likely low volume, a semi-kit (all the
    surface mount parts soldered down, but the remaining parts -- two DIP
    switches and four 2 pin headers -- left as an exercise for the buyer,
    would cost in the range of $80-$100.

    A fully assembled and tested version would probably be $100-120 (most of
    the increased cost is testing, not soldering down the few remaining parts).

    I've tried to be conservative in these prices and I hope the actual
    price will be lower, but don't know that for sure at this point. A lot
    depends on quantity so there's a bit of chicken and egg here.

    I'm hoping to collect no-obligation expressions of interest from this
    group, assuming prices in the ranges described above. If you'd be
    interested in buying one or more Clock-Blocks, please let me know
    privately how many, and what version.

    Thanks!

    John Ackermann
    jra@febo.com
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  2. Re: Query: Interest in clock synthesizer module -- useful for stabilizingPC timekeeping (among other things)

    John Ackermann N8UR wrote:

    > I'm working on a project for TAPR (http://www.tapr.org) that might be of
    > interest to the timekeeping community.
    >
    > It's a very simple clock synthesizer called the "Clock-Block" that
    > accepts a reference input in the roughly 2-50MHz range and generates an
    > output in the 5-250MHz range, programmable by a series of jumpers or
    > switches.
    >
    > My primary inspiration for designing this circuit was Poul-Henning
    > Kemp's suggestion that it would work nicely to replace the crystal
    > oscillator on a PC to allow much more stable timekeeping. For example,
    > it can generate 14.318182MHz or 33.333333MHz from a GPS disciplined
    > oscillator or other stable reference. A PC with a Clock-Block and
    > external reference should be able to keep *very* good NTP time.
    >
    > But there are likely to be other interesting uses as well; one I'm
    > considering is replacing the clock in a sound card to get precise sample
    > rates.
    >
    > There's information about my prototype (and a picture) at
    > http://www.febo.com/time-freq/hardware/ICS525/
    >
    > The prototype works well and we are now ready to move to production.
    > Before we do that, I'd like to get a sense of the interest level (if
    > any), and in particular whether there's enough demand to warrant an
    > semi-kit or assembled version instead of TAPR's usual bag o' parts.
    >
    > As a kit, the Clock-Block would be quite inexpensive; we haven't
    > finalized the BOM yet but I believe TAPR would be able to sell it for
    > well under $50.
    >
    > However, assembly may be problematic for some folks, because the
    > synthesizer chip is a "SSOP" surface mount package with about 0.5mm lead
    > pitch. I've had no trouble putting down these chips using a microscope
    > and small iron but not everyone may be willing to take on that challenge.
    >
    > I am guessing that given the likely low volume, a semi-kit (all the
    > surface mount parts soldered down, but the remaining parts -- two DIP
    > switches and four 2 pin headers -- left as an exercise for the buyer,
    > would cost in the range of $80-$100.
    >
    > A fully assembled and tested version would probably be $100-120 (most of
    > the increased cost is testing, not soldering down the few remaining parts).
    >
    > I've tried to be conservative in these prices and I hope the actual
    > price will be lower, but don't know that for sure at this point. A lot
    > depends on quantity so there's a bit of chicken and egg here.
    >
    > I'm hoping to collect no-obligation expressions of interest from this
    > group, assuming prices in the ranges described above. If you'd be
    > interested in buying one or more Clock-Blocks, please let me know
    > privately how many, and what version.
    >
    > Thanks!
    >
    > John Ackermann
    > jra@febo.com
    > _______________________________________________
    > questions mailing list
    > questions@lists.ntp.isc.org
    > https://lists.ntp.isc.org/mailman/listinfo/questions
    >


    I think the big issue here would be replacing the PC's native hardware.
    It would void the warranty (at the very least).

    It would have to be removed before anyone would attempt any required
    repairs, etc, etc.

  3. Re: Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)

    Very interesting ideea, but I have a question: Did you take into
    consideration the temperature ?

    I made some empirical observations and the main problem of the 14 MHz
    crystal on the motherboard is the temperature. If you compensate the
    mainboard crystal the results are great.

    A good ideea is to replace the crystal itself with an OCXO but the
    price is higher enough to discourage a self-starter.

    As we see here:
    http://www.mirror99.com/20050701/sym...ystal_jde.jspx

    at this price we could buy a rubidium oscillator.

    If you have to replace something on the motherboard, an ideea is to
    replace the crystal with a better one:
    http://www.rfx.co.uk/pages/ocxoindex.html.


  4. Re: Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)

    Searching ebay.com I found something intereseting. You may search for
    "10MHz GPS disciplined Parts Kit w/PCB for Isotemp OCXO!" and you'lll
    found an external OCXO 10MHz reference.


  5. Re: Query: Interest in clock synthesizer module-- useful for stabilizing PC timekeeping (among other things)

    Eugen COCA said the following on 08/17/2006 01:53 AM:
    > Very interesting ideea, but I have a question: Did you take into
    > consideration the temperature ?
    >
    > I made some empirical observations and the main problem of the 14 MHz
    > crystal on the motherboard is the temperature. If you compensate the
    > mainboard crystal the results are great.
    >
    > A good ideea is to replace the crystal itself with an OCXO but the
    > price is higher enough to discourage a self-starter.


    The idea behind the ClockBlock is to replace the crystal with something
    tied to an external reference. For example, if your motherboard has a
    66MHz crystal, the Clock-Block could be programmed to generate that
    frequency using a 5 or 10MHz OCXO, GPSDO, Rb or Cs, or whatever as a
    reference input. The reality is that virtually any oscillator will be
    better than the 29 cent rock that's on the motherboard, but obviously
    the better the reference the better the timekeeping.

    John
    ----
    >
    > As we see here:
    > http://www.mirror99.com/20050701/sym...ystal_jde.jspx
    >
    > at this price we could buy a rubidium oscillator.
    >
    > If you have to replace something on the motherboard, an ideea is to
    > replace the crystal with a better one:
    > http://www.rfx.co.uk/pages/ocxoindex.html.
    >
    > _______________________________________________
    > questions mailing list
    > questions@lists.ntp.isc.org
    > https://lists.ntp.isc.org/mailman/listinfo/questions
    >
    >


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  6. Re: [time] Query: Interest in clock synthesizermodule -- useful for stabilizing PC timekeeping (among other things)

    Steve Herber said the following on 08/17/2006 01:16 PM:
    > Thank you for your efforts. The device looks good and simple. KISS.
    >
    > Can you explain to me, and maybe the list, how a person with a linux ntp
    > server would use this device, and any other equipment, to build a more
    > stable clock system? What equipment, what changes to the equipment,
    > what skills would be needed, and what the result should be.
    >
    > For example, I am interested in using the Garmin pps out GPS system but
    > don't have the time or ready skills to attach one to my PC. Would I
    > have the same problem with your device?


    The Clock-Block is going to require some willingness to do-it-yourself
    (or find someone to do it for you!) with a soldering iron.
    Unfortunately, if you're not ready to interface a GPS to the PC, you're
    probably not going to be comfortable installing this board.

    The idea is to replace the $0.29 cent crystal that controls your PC's
    clock with something more stable. The Clock-Block basically serves as a
    translator between the frequency of that more stable clock (for example,
    10MHz) and the frequency your PC expects (which might be anything from 5
    to 50MHz). The better the quality the external reference, the better
    the timekeeping -- you can use anything from a cheap crystal, to a
    Cesium atomic beam frequency standard, with corresponding results.

    So, in order to use the Clock-Block, you need an external frequency
    reference and the willingness/ability to remove the crystal or
    oscillator on your PC motherboard and solder a piece of coax from the
    Clock-Block to replace it.

    The end result will be an NTP server that shows a drift of approximately
    zero (how approximately will of course depend on the quality of the
    external reference signal).

    John
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