[Gb-ccb] CCB interface questions (fwd)

[Brian Mason]

Thanks- this is quite clear. Just to make sure... It sounds to me like
we'll have 16 input ports J1 ... J16 (to follow a GB convention) which
correspond to the individual ADCs-- frequency assignments and module
assignments are irrelevant to the CCB software interface (they might
however impact a more optimal physical layout of the circuitboard). It is
the norm at GB to designate cabling connections via a "cabling file"
external to (read by)  the manager as you've suggested.

So we will have output like
 
J1(00) J1(01) J1(10) J1(11) J2(00) ... J16(11)

*always*... with some of the phase bins empty when less than 2 switches
are active, and all the last J13...J16 bins (16 of them) empty for 3mm.

You may find it interesting to review
http://wiki.gb.nrao.edu/bin/view/Projects/KaSoftware

where I've started outlining what needs to be in the CCB FITS file that
the manager writes. (There is also much else in this page which doesn't
pertain to the CCB).  Note that any actual labels-- eg "CCB Port" are only
nominal, although I think we've actually adopted the 'RX Output' port
labels.

 Brian

On Thu, 11 Mar 2004, Martin Shepherd wrote:

> In my reply to Melinda's query I unfortunately got the ordering of the
> phase-switch bins completely wrong. Sorry for the confusion.
> Fortunately Tim's reply reminded me.
> 
> The ordering of the phase-switch bins in the data array for a given
> ADC, won't be their time order within the phase-switch cycle, as I
> incorrectly stated in my previous email, but rather:
> 
>         Switch A   Switch B
>  Bin 0:   0           0
>  Bin 1:   0           1
>  Bin 2:   1           0
>  Bin 3:   1           1
> 
> Where 0 means that the phase switch is off, and 1 means that it is
> on. In other words they will be ordered in the binary order of a 2-bit
> integer formed by concantenating the boolean control bits of switches
> A and B.
> 
> Note that there will always be 4 bins per ADC, regardless of how many
> phase-switches are enabled. The bins that aren't sampled will simply
> hold zeroes. Thus the data array will always contain 64 elements.
> 
> Martin
> _______________________________________________
> gb-ccb mailing list
> gb-ccb at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/gb-ccb
> 

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Brian Mason                           | office: +1(304)456-2338
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