[evlatests] S band default frequencies

[David Harland]

Juergen,

The changes i'll make, based on Barry's response, will apply in the OPT 
to the EVLA antennas / VLA correlator combo.  We can address the 
settings for EVLA/WIDAR once the WIDAR user interface is available for 
testing.  For a look at the default LO tunings currently used in the SSS 
code for EVLA/WIDAR, see the entry on the test program page 
<https://staff.nrao.edu/evla/sss/sssTestPgm.shtml> called 
"EVLA...Auto.Config'n".  The default LO tunings are in an xml file for 
each changing.

David

Juergen Ott wrote:
>
> I guess that another constraint is to place the frequency at least 
> close to center of the band to take advantage of the wider continuum 
> bandwidths that will become possible.
>
> Juergen
>
> Juergen Ott wrote:
>> Ideally you want the recommended continuum frequencies for each band 
>> as the default.  This is typically the spot with the lowest Tsys and 
>> away from any known RFI. Not sure what thwy are for the EVLA.
>>
>> Juergen
>>
>> David Harland wrote:
>>  
>>> I don't know how much it matters for the hardware config portion of 
>>> the OPT, since users are expected to choose their own frequencies, 
>>> but we do start w/ defaults & it would make sense to pick the same 
>>> ones as are picked elsewhere. Right now i think for each band we 
>>> default to the center of the nominal range of the bands. This is 
>>> what i found using webtest <https://webtest.aoc.nrao.edu/rct>:
>>>
>>> 4 73.75MHz
>>>
>>> P 320.25MHz
>>>
>>> L 1.6GHz
>>>
>>> S 3.0
>>>
>>> C 6.0
>>>
>>> X 10.0
>>>
>>> Ku 15.0
>>>
>>> K 22.25
>>>
>>> Ka 33.25
>>>
>>> Q 45.0
>>>
>>> If anyone wants these adjusted, let me know the value to use for a 
>>> particular band. Right now we use the same default frequency for IFs 
>>> AC and BD. If that should not be the case, let me know the default 
>>> freqs by band and IF.
>>>
>>> David
>>>
>>>
>>> Ken Sowinski wrote:
>>>      
>>>> The satellite radio signals at 2300 MHz are strong ebough in LCP to
>>>> seriously distort the attenuator settings in the down converters such
>>>> that power as seen at the VLA T5s is much too low.  To avoid this
>>>> I suggest moving the default S band frequencies for use with the
>>>> old correlator from 3000 and 3050 MHz to 3500 and 3550 MHz.  This
>>>> will move 2300 MHz out of the downconverter input filter bandpass.
>>>>
>>>> I can change the default frequencies in the parameters DB, but does
>>>> anything else (such as obs2script) need to be changed as well?
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