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 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
