[time-nuts] PICTIC II

Joseph Gray jgray at zianet.com
Sun Jun 27 19:01:28 EDT 2010


As asked by another, please post a PDF of the schematic. I don't have
any software installed that can read the files you posted.

Joe Gray
W5JG

On Sun, Jun 27, 2010 at 3:54 PM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> On 06/26/2010 09:11 AM, Richard H McCorkle wrote:
>>
>> Fellow Time-Nuts,
>> When I first uploaded the Simple PICTIC interpolating time interval
>> counter to the K04BB site in 12/08 and presented it to the group as
>> a Christmas present my goal was to get amateurs building their own
>> interpolating time interval counters for GPS monitoring and making
>> improvements to my design. The interpolator in the PICTIC was
>> “borrowed” from an early HP counter with minor modifications so I
>> didn’t design it and had no personal attachment to it.
>
> Which counter? Just curious.
>
>>   Over the last 18 months I have developed a new diode switched
>> interpolator based on the comments made on line and have thoroughly
>> tested it. Some suggestions made improvements in the performance and
>> some resulted in poorer performance. I incorporated those suggestions
>> that made improvements, eliminated those that made things worse, and
>> once I was satisfied I sent the revised interpolator design directly
>> to Bruce off line. Based on comments and suggestions he returned
>> during a long series of emails I incorporated additional changes in
>> the code, front-end, and interpolator designs and tested those
>> changes until I was satisfied with the performance and he had no
>> further comments. I am finally satisfied with the new design and
>> admit that by incorporating the majority of the suggestions made
>> the new interpolator has significantly better linearity than the
>> HP interpolator used in the PICTIC and it is now suitable for
>> higher resolutions.
>>   I was reluctant to post the PICTIC II in this forum, as I don’t
>> want to get in another public discussion of its faults without any
>> discussion of the merits of a $50 serial output interpolating TIC
>> on a 3.8” x 2.5” thru-hole board designed for amateur construction.
>> The K04BB WIKI PICTIC page was recently updated to include the
>> PICTIC II code and ExpressPCB board layout and schematic files for
>> those that might be interested.
>>
>> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>>
>> The PICTIC II incorporates the new interpolator, requires a delay
>> between the inputs, and uses a low stability XO timebase with
>> software peak detection for calibration with provision for an
>> external timebase like the PICTIC to minimize size and cost.
>
> Sounds interesting. What is the ball-park figures? Resolution, jitter,
> linearity?
>
> Cheers,
> Magnus
>
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