[evla-sw-discuss] VCI stationHw element creation

[David Harland]

This note pertains to the stationHw message of the VCI and my 
supposition that
the SSS software no longer needs to be the prospective producer of this 
message.
I'm looking for someone to either concur with or refute that statement.


Background
==========

In the original incarnations of the VCI, up through version 3.3 (current 
vers
is 3.5), this message required a different configuration for a given antenna
for each IF setup below:

  + Four 3-bit pairs
  + Two 8-bit pairs
  + Two 3-bit pairs and one 8-bit pair.

(See pages 48 & 49 of vers 3.3 to confirm the above.)

Because the content of this message had depended on the initial 
quantization of
the basebands, we were really stuck in the situation of needing to send this
message prior to every scan.  This made the job of creating these msgs fall
most naturally to the SSS software.


Current Situation
=================

On p54 of vers 3.5 of the VCI document you will see that the baseBandHw 
element
of the stationHw element has fewer data fields than it had had in 
version 3.3.
This latest construct has nothing that needs to change from scan to scan.
(I'm choosing to ignore the noiseDiode and monitorData elements for the 
moment.)
So long as the connections from antenna to station boards stays undisturbed,
this message need not be resent.

One key for the SSS software, though, is that the mapping of antenna IF 
to bbId
be as shown on page 16 of rev. 2.1 of the EVLA Correlator System 
Numbering Plan.
In the obs prep tool the SSS software will know which antenna IF a user is
splitting into subbands, and that software must be able to predictably 
map that
IF to a BBID.


noiseDiode & monitorData Elements
=================================

I don't have a feel for how often "normal" observers would want to play with
these elements.  If these are used very rarely, then perhaps the OPT is not
the place to gather this information.  If the consensus is to gather 
this info
in the OPT, then we will need to have something the OPT could hand this 
data to,
so that that "something" could then add that info to the stationHw msgs and
send them to the configuration mapper.