[time-nuts] Sidereal time

J. Forster jfor at quik.com
Fri Jan 15 17:44:09 UTC 2010


Looing at the schematics quickly, it looks like 1 MHz. There is a clock
failure circuit on that line.

-John

=================


> Hi
>
> So now the question becomes: With only modest / reversible butchery,
> what's
> the slowest pulse train it will accept?
>
> 1 MHz is not to bad to generate. Something slower would still be easier
> with
> a computer. If 1 ms accuracy is "good enough" then driving it with
> anything
> over 10 KHz is kind of overkill.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of J. Forster
> Sent: Friday, January 15, 2010 12:28 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Sidereal time
>
> The external input triggers logic (via a selectable divider). It would
> easily go +/- 50% in frequency.
>
> Artek Media has the manual.
>
>
> -John
>
> =============
>
>
>> 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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>
>
>
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