[time-nuts] Sidereal time

Bob Camp lists at cq.nu
Fri Jan 15 14:09:31 UTC 2010


Hi

There may be a gotcha.

If that HP box has their standard time base in it, your idea isn't going to
work. The normal HP approach is to lock a local oscillator up to the
incoming reference input. That way they can handle a bunch of different time
base inputs without much bother. Their standard VCXO does not have enough
range to lock to a reference 0.03% off frequency.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Brian Kirby
Sent: Thursday, January 14, 2010 10:13 PM
To: precise time
Subject: [time-nuts] Sidereal time

I would like to have an electronic clock to keep sidereal time.  I am 
planning on using a HP 59309A, which can except an external clock of 
1/5/10 Mhz.

According to Wikipedia sidereal time is 23 hours 56 minutes and 4.091 
seconds - a total of 86,164.091 seconds

So 86,400 seconds for a normal "atomic defined" day divided by 
86,164.091 = 1.002,737,903,89

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.

Is my math and theory correct ?

Brian - KD4FM

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