[evlatests] X-band subband ordering

[Michael Rupen]

There is clearly something wrong with the X-band labelling.  I would
prefer to defer further & deeper tests until we've switched completely
to the new "automated" approach to getting metadata through to the SDM,
next week.  There are many tests to do but we will just have to re-do
them when the new system is in place giving (for instance) both baseband
pairs at the same time.

On the VCI side there are many possible confusions.  Note for instance that
we auto-magically change the filter sideband flippers so that the CBE
*always* receives USB data, at every band.  We confirmed yesterday that
this does indeed work.  There is a great deal of development going on at
the moment with the VCI and the Configuration Mapper.  Again it would
seem wise to let the dust settle before checking the details of such
messages.

                     Michael

>
> Looking at some VCI documents with Adam earlier today we were surprised to
> see LSB used for all bands where I would have thought X-band to need the
> opposite sideband sense...
>
> -W
>
> On Fri, 19 Feb 2010, Rick Perley wrote:
>
>>    A quick perusal of X-band data shows that the ordering of the
>> subbands is reversed:
>>
>>    The correct spectral features (and continuity of phase) are
>> recovered if the subbands are ordered {4,3,2,1}, rather than their
>> current ordering {1,2,3,4}.  Note that this is not the same as simply
>> reversing the frequency axis.  It appears the frequency ordering within
>> each subband is correct (and runs 'backward').
>>
>>    Data quality looks good, but a closer inspection is needed.
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