[time-nuts] ensemble of standards

Bob Camp lists at rtty.us
Sun Dec 30 03:39:46 UTC 2012


Hi

Having written code for a 4K PDP-8, I suspect that more of the heavy lifting was hand optimized assembler rather than Fortran. More or less, compile it / it doesn't fit / poke into it / fix it / recompile it / poke it some more / give up & hand optimize the problem areas.

Bob

On Dec 29, 2012, at 10:32 PM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> On 30/12/12 02:46, cdelect at juno.com wrote:
>> Also about ensembles,
>> 
>> http://www.mksa.deit.univpm.it/biblioteca/sala_tecnica/scaffale_strumenti
>> /Campioni/EPSG070861.pdf
>> 
>> This article describes combining 4 HP 5071A standards.
>> 
>> Description on page 2 and block diagram in figure 2.
>> 
>> Unfortunately no details on the controller are given!
>> 
>> It's what I'd like to do to two or more HP 5065A
>> 
>> Anyone know what they did in the controller?
> 
> I'd assume that this is similar to what is described in Chapter 9 of NBS Monograph 140, by Dr. David Allan and friends:
> 
> http://tf.boulder.nist.gov/general/pdf/194.pdf
> 
> When reading the FORTRAN code, one has to realize that the ER calculations is hard-wired to the way that the NBS setup at the time where done, so that the 8 clocks was compared by a number of pair-wise measures and that the time-differences is combined as needed where some of the clocks becomes transfer standards in the comparison back to the primary reference standard. Clock 3 is the main clock in the hookup.
> 
> A modern view on things is found here:
> http://tf.boulder.nist.gov/general/pdf/816.pdf
> 
> The original time-scale algorithm ran on a PDP-8 machine with 4k word memory, coded in Fortran by Dr. Allan. Today they run using a pair of redundant 386 machines and using a blend of Jim Greys buffer and mixers and that of commercial time-interval measurement rig.
> 
> Cheers,
> Magnus
> 
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