[time-nuts] 2.5 Ghz 12 digit counter project

Don Latham djl at montana.com
Fri Dec 28 18:42:01 UTC 2012


Second that!  modular prescalers available from RFBay, need only 12v,
can get enough from the counter.
Don L
Bob Camp
> Hi
>
> As far as I can see, you would do *much* better with a surplus HP
> counter (sub $200 or even sub $100) and some sort of pre-scaler.
>
> Bob
>
> On Dec 28, 2012, at 2:51 AM, Bruce Griffiths
> <bruce.griffiths at xtra.co.nz> wrote:
>
>> Tom Harris wrote:
>>> Watch out for Silicon Chip designs, they have a habit of not making
>>> the
>>> source code available, which you only find out at the end of the
>>> project. I
>>> suppose that it is to allow the author to make a few extra $$ selling
>>> programmed micros. They had a nice 3 phase inverter design a year ago
>>> that
>>> had this problem, I wrote to the author promising not to distribute
>>> the
>>> source, I just wanted to read it, but didn't even get the courtesy of
>>> an
>>> answer.
>>>
>>> I suspect that this counter is like the inverter, an oldish design
>>> that is
>>> not worth building as you can get the same for half the cost out of
>>> China.
>>> What makes it worthwhile is getting the hardware&  the source code,
>>> so that
>>> you can tinker with it.
>>>
>>> Actually I had a look at the counter and it looks similar to the 8
>>> digit
>>> designs using the Intersil 7217 IC from the 80's.
>>>
>>> Gripe ends.
>>>
>>> On 28 December 2012 06:12, Paul Amaranth<Paul at auroragrp.com>  wrote:
>>>
>>>
>>>> Did anyone see the article in the December Silicon Chips magazine
>>>> about
>>>> building a 12 digit 2.5 GHz counter?  It has an option for a GPS
>>>> 1pps
>>>> input so you could have some expectation that the last couple of
>>>> digits mean something.  The website only has the article cover page
>>>> in pretty much unreadable type.
>>>>
>>>> --
>>>> Paul Amaranth, GCIH  | Rochester MI, USA
>>>> Aurora Group, Inc.   |   Security, Systems&  Software
>>>> paul at AuroraGrp.Com   |   Unix&  Windows
>>>>
>>>>
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>>>>
>>>
>>>
>>>
>> I've read the entire set of articles and like most of the designs from
>> this particular designer its largely an unadulterated piece of junk.
>>
>> Aside from the usual logic design errors I've come to expect from this
>> designer the GPS PPS input is used directly to set the gate time so
>> jitter on this signal directly (several tens of nanaosec or even more
>> if sawtooth error is present better if the PPS is derived from a
>> GPSDO) affects accuracy.
>>
>> Bruce
>>
>>
>> Bruce
>>
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>
>
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-- 
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com





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