Heresy: Why do you really NEED super accurate siderial time? If you are using it to point a telescope, you only need it accurate enough to get the guide stars into the field. Remember, the atmosphere refracts kinda randomly.
-John =============== > 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. >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
