[time-nuts] Sidereal time

Hal Murray hmurray at megapathdsl.net
Fri Jan 15 09:27:37 UTC 2010


> If I set the 59309A to 10 Mhz external clock and dial a synthesizer up
> to 10.0273790, the unit should be able to keep sidereal time. 

Sounds good to me, but since this is time-nuts, you need a GPIB connection to the synthesizer so you can tweak it to track the details from IERS.

It would be interesting to work out the details and see which is the most-significant digit that changes.  Would you need to tweak the synthesizer, or are the changes off the bottom?



Plan B:  Do it in software.

Consider a small CPU running from 10 MHz that can drive a display.  If it has a connection to the outside world, then you can tell it how many ticks per sidereal second and when to start using the new value.

Small LCDs are not expensive.  There are some designed to fit into a disk/CD slot on PCs.


SparkFun has Arduinos for $30 and LCDs for $14 and up.  Some assembly required.

Or get their Serial Enabled LCD for $30 which includes a PIC16F88 and figure out how to reprogram it to keep time.


-- 
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