[time-nuts] Sidereal time

[Bob Camp]

Hi

Gee, there's an idea. Grab a TBolt and a simple micro. Hook them up to something like a Soekris and a big LED display. Network it up to get the latest offsets. Toss in a bit of wire and software and you get very high accuracy sidereal time. 

If NTP is "good enough" you could dispense with the TBolt and part of the wire. Tough to see the difference between NTP and GPS on a wall clock....

Bob

On Jan 15, 2010, at 4:27 AM, Hal Murray wrote:

> 
>> 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.
> 
> 
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
> 
> 
> 
> 
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