[evlatests] [evla-sw-discuss] parameter simplification for the VHF receivers

[Michael Rupen]

In the SDM, the Feed Table has separate rows for each Spectral Window.
Thus one can track the feeds & receivers independently for each SpW, which
is what we want.  This would require a change in MCAF, which currently
assumes all SpWs in the same configuration use the same receiver. That's
not a big deal, except the Executor (or someone) has to tell MCAF which
SpW use which receiver/feed; or we embed the knowledge that 0-100 MHz
(say) is 4-band or whatever, in MCAF itself.

       Michael


>
> do they come through different receivers within the box?
>
> i'm concerned about being able to distinguish between them in the SDM.
>
> 	-bryan
>
>
> Ken Sowinski wrote, On 6/27/12 9:30 AM:
>> Currently parmainator distinguishes between 75 MHz and 300 MHz for
>> band related paramters.  The parameters of interest are subreflector
>> rotation and focus and band-dependent delays.  Also there are T_cals,
>> which are now obsolete in the paramters DB, and tables of attenuator
>> settings, also obsolete.
>>
>> I suggest that we have only one band code "VHF" to select the low
>> frequency receivers.  Receiver.java will transform any reference
>> to "75MHz" or "300MHz" to "VHF".  This allows us to keep only
>> one set of parameters in the DB, rather than two identical sets;
>> prevents possible mistakes when two sets are maintains; more
>> accurately reflects the current hardware; and, eliminates the confusing
>> necessity of having to know whether the script selected "75MHz" or
>> "300MHz".
>>
>> The rational is that there is one receiver box containing all
>> receivers.  Its single output (dual polarization) is conneted
>> to one T301 input.  Regardless of which band is selected, the
>> hardware configuration is the same and the same wideband signal
>> is presented to the T304.
>>
>> Would doing this prevent anything that would be practical and useful
>> with the current scheme?
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