[evlatests] Antenna 14 FRM interference

[Frank Schinzel]

Of course I should have added that all where MJPs are installed the 
interference is present on baselines to antenna 14 and on all baselines 
with no MJPs it is of course gone. The only exception is antenna 4 where 
the receiver itself seems to be picking up low level of interference 
without having an MJP attached that correlates with 14, which I think is 
interesting to note.

     Frank

On 06/02/2016 04:31 PM, Frank Schinzel wrote:
> Hi everyone,
>
> We did today a test today to verify the extend of the FRM interference 
> from antenna 14 at 4 band. We observed Cas A at low elevation with the 
> antennas facing West. We did one 5 min scan with the FRM off and 
> another one with the FRM on. The interference clearly shows up. What 
> surprised me the most is that cross-correlation products in IF6 show 
> this as correlated interference present across the entire B array (see 
> attached config.pdf).
>
> For your enjoyment I have made comparison plots across the band for XY 
> auto-correlations of antenna 14 (AC14_FRM_off.pdf, AC14_FRM_on.pdf, 
> and AC14_FRM_on_zoom.pdf).
>
> I also added an example of two cross-correlation plots with FRM on and 
> off just showing IF6 XY (XC_FRM_off.ps and XC_FRM_on.ps). Those are 
> for two baselines one between 14 and the neighboring antenna 23 and 
> one where I didn't see strong interference in the cross-correlation 
> between antennas 14 and 22.
>
> It would be great if we could address this issue in the near future 
> before we take some more 4-band data.
>
>      Frank
>
>
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