[time-nuts] More details on IEEE Spectrum clock competition

[Jeff Mock]

Philip,

I think this sounds pretty reasonable, here's my 2-cents worth.

I think calibration should be part of delivering the clock.  You can 
imagine a designer developing elaborate models for the timebase and you 
don't want to stifle creativity here.  I think calibration is part of 
the delivered clock and not done by the judges.  The clock should be 
settable by a layperson, but I think you should let people go wild 
calibrating the clock.

The two big enemies the designer fights will likely be environmental and 
aging.  I think you've covered a good environmental specification, but 
aging should be incorporated into the contest.  For example, a temp 
compensated xtal oscillator my be calibrated to well less than 0.1 ppm 
and look really fantastic for a few days, but the crystal might age 2-3 
ppm over the first year of operation.

I imagine running the contest over a few months.  At some submission 
date the clocks are collected at your office, set to the current time, 
and left to run for a few months (or however much time you have).  At 
the end of 3-months all of the clocks are measured and a winner is 
picked.   Maybe you can publish intermediate results for dramatic effect.

Tom Van Baak has a nice story on his website about how he got interested 
in precision timing, http://www.leapsecond.com/.  He wanted a clock that 
would be accurate to better than 1-second over a year so that he could 
appreciate and adjust the clock during a leapsecond.  I don't know how, 
but I think that it might be possible to build a clock for this contest 
that meets that criteria.  If so, I think the entries need a feature for 
measuring accuracy more precisely.  I suggest requiring that the entires 
have a BNC connector that outputs a TTL level pulse once per second, the 
rising edge of the signal marks the beginning of a second (this is 
usually just called a PPS signal).  The accuracy of the clock can be 
done visually to 1s resolution, finer measurement can be done with 
comparison against PPS from a GPS receiver.

jeff



p.ross at ieee.org wrote:
> A number of people have asked for more details on IEEE Spectrum's digital 
> clock competition, so we've formulated the following list. Throughout, the 
> idea is to build a clock that an ordinary person would want to use, in an 
> ordinary home. That's why we want a display that can be read with ease 
> from across a room.
> 
> 
>         Operating environment and other specs for IEEE Spectrum's Digital 
> Clock Competition:
>  
>         --between 10 and 50 degrees C
> 
>         --between 0 and 100 percent relative humidity
>         --with seven-segment LED display, no smaller than 0.56 inches
>         --no limit on power
>         --calibration should be within the grasp of a layman
>         --lacking an oscilloscope here in the office, we will check 
> accuracy against a WWVB or GPS signal (other suggestions--even volunteers 
> to help in the judging--are welcome)
>         --parts to be available from any of the big distributors 
> (RadioShack, Mouser, DigiKey, Maplin, etc.) or, in sufficient quantities 
> (100s, say) from a surplus store
> 
> 
> 
> 
> Philip E. Ross
> Senior editor
> IEEE Spectrum Magazine
> 212 419 7562
> http://www.spectrum.ieee.org
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>