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

[Eric Fort]

over what durration will the clocks accuracy be measured?  (seconds,
minutes, hours, days, months, (years)?

"accuracy to be measured before disciplining with GPS, WWVB....."
"calibration should be within the grasp of a layman"

Could some clarification be given here?  I'm thinking that the clock could
be self calibrating say automatically or by user button press but this
presents a chicken and egg problem in light of the quotes above.  Many of
the designs I've seen previously keep an internal memory that tracks and
allows compensation for parameters such as drift, aging rate, and temp
coefficient updating these variables when connected to a known better
reference.  in this way the accuracy improves with time.  while a layman
could calibrate this type of clock quite easily (or would not need to as the
clock would calibrate itself) any calibration pretty much by definition is a
comparison to a better reference (wwvb, gps, hydrogen maser,  rubidium,
cesium beam, etc.)  so how do you expect calibration to be accomplished
without, use of a better standard?  would such a device be allowed to
remember and store calibration factors during its initial calibration or
would this fall into the category of discipline?  I would say that the
initial determination and programming of calibration factors (which will
vary among devices) is calibration, after which it becomes discipline as the
routine continues to run.  What's your interpretation?

Eric

On Nov 30, 2007 6:43 AM, <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
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