[evlatests] S band default frequencies

Juergen Ott jott at nrao.edu
Wed Apr 8 16:48:12 EDT 2009


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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