[mmaimcal] forwarded message on subarrays from Jacob Baars

[Steven T. Myers]

I still see little benefit from distinguishing between the number that
the correlator can handle (6 proposed) and the software (8 proposed),
and as per my previous reply to Stephane's first mail on the subject I
prefer to set the latter two to 8 (my 4 "hard" versus 8 "soft" 
subarrays).  This will simplify things and will be one less complicated
distinction that the user needs to be aware of.  Unless there is a
compelling case that the correlator needs to have 6 instead of 8, I
strongly urge us to keep things as simple as possible.  (The cost of
another 4 first LOs is an example of a good reason to distinguish between
4 and 8 there, but 4 isnt enough for everything...).

  -steve


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On Tue, 11 Apr 2000, Al Wootten wrote:

> Imcalers:  Comments on this note from Jaap?  I think it looks workable.
> 
> Al
> 
> I have finally found the time to work on a possible wording of the 
> "sub array" issue.
> We, or at least some of us, discussed that a short note might be 
> appended to the ALMA System Preliminary Design Recommendations, as 
> well as to the ASAC minutes. Using mainly a proposed version by 
> Stephane, here is a draft proposal of such a note.
> 
> Any comments and improvements, as well as alternatives to its 
> dissemination are are welcome.
> 
> regards,
> 
> Jaap
> =====================================
> DRAFT
> 
> There exists confusion, and possibly differences of opinion, among 
> the scientists and engineers of the ALMA Project as to the final 
> decision regarding the number of sub-arrays, which would be supported 
> in ALMA. After discussions in the ASAC and among the Project 
> Scientists and System Engineers, we have agreed that the following 
> definition is appropriate.
> 
> We distinguish three types of sub-array levels:
> 
>      1) Number of different frequencies the LO system can drive simultaneously
>          Specification: up to 4.
>      2) Number of antenna sets the correlator can treat independently:
>          Specification: up to 6
>      3) Number of antenna sets the software can handle independently:
>          Specification: up to 8
>      4) Independent control of any antenna will be possible (for 
> maintenance and repair).
> 
> 
>