[evlatests] Mystery Moon Test

[Rick Perley]

     Having the T302 attenuators on would depress the PDif values. But 
why would it cause such a huge non-linearity in the PDif values?  
Perhaps a clue here ...

On 12/17/2015 08:36 AM, Ken Sowinski wrote:
> On Thu, 17 Dec 2015, Rick Perley wrote:
>
>>    Rob ran the 'Moon compression test' last month at X-band.  The 
>> results are bizarre:
>>
>>    1) We expect a power increment of about a factor of 5 to 8. This 
>> is what was observed in the 'PSum' digital power.  So far, so good.
>>
>>    2) The 'set and remember' regimen was applied when the source was 
>> on the moon.  The digital power level should be about 15, when on the 
>> moon.  This was also the case.  Still good....
>>
>>    3) We then expect a 'PDif' compression (PDif on moon)/(PDif off 
>> moon) of about 0.9.  In fact, this ratio was about between 0.1 and 
>> 0.4 (!!!!!)  That is, for every antenna and every IF channel, the 
>> PDif when on the moon was only 10 to 40% of the value when on cold sky.
>>
>>    This is a level of compressin that I have never seen before.
>>
>>    It may be worth noting that the PDif values, which are normally 
>> hundreds of millicounts, where only 10 -- 50 millicounts.
>>
>>    Something is wrong.  Any ideas?
>
> Did someone turn on the T302 solar attenuator?
>
>
>>    Rob reports that the TPD values (recorded in parallel) were also 
>> weird.
>>
>>
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