[evlatests] VLA Tests/ 3bit sampler update

[Vivek Dhawan]

Hi all,

here is the picture I was unable to show at the meeting.

The plot shows the 8 3-bit samplers on each antenna, frequency going
vertically over 2GHz (in 16 subbands) for each sampler (baseband) A1,
B1, etc. All samplers are fed the same 2 GHz of sky.

The colour coding is by signal-to-noise, red is bad, green is good, blue
is best. After the sampler replacements are done, we will have no more
yellow on the array, the few remaining slightly weaker ones will look
like 7C2 and 8B2,C2. These we will to live with as we do not have the
chips to replace them all.

The samplers 7B2 and 8A1, B1 were in a funky state at the start of the
first block of data, they are fine in the second block after a reset.

7B1D1 and 8A1C1 are Hittite samplers the rest are the old Teledynes.

I will do a more thorough analysis, comparing 8 and 3-bit samplers,
after the replacements are all done.


On 04/22/2015 03:07 PM, Rick Perley wrote:
>      There are two volunteers for the meeting tomorrow.  So let's go ahead and
> have this:
>
>      10AM, Rm 317, 23 April.
>
>      Topics:
>
>      1) Doug Whiton:  Effect of Wind Stow Limits on VLA antenna operations
>
>      2)  Vivek Dhawan:  Update on performance of the Hittite Samplers.
>
>      There is time aplenty for more topics.
>
>
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