[evla-sw-discuss] tone detection parameters

[Brent Carlson]

Some time ago, a decision was made to allow for phase cal tone parameters
on the VCI, in case the VLA tracks spacecraft.  Normally, it would just
have the 1st order coefficient.

Brent


> On Fri, 23 May 2008, Michael Rupen wrote:
>
>>   I'm assuming the review will concentrate on general areas of design
>> rather than page-by-page detailed comments.  Many details will of course
>> arise when you read the beastie, but fiddly bits should probably be
>> discussed on evla-software rather than in a big committee meeting.
>
> Herein the first fiddly bit.
>
> This whole comment is, perhaps, moot since we have no pulse-cal
> generators on the EVLA antennas and no plans to install any.  It
> may be relevant if Pietown is connected or VLBA data is to be
> correlated.
>
> If we had implemented pulse-cal tone extractors before the delay
> modules then the only parameter needed would be the frequency of
> the desired tone relative to baseband.  Instead there is one per
> subband after all the delays has been inserted, so the tone
> detection, as noted by Brent and Dave, must take into account the
> delay and delay rate imposed ahead of the detection.  The VCI
> suggests this information is provided from the outside.  Rather,
> all the information needed already exists in the station board
> CMIB, so it should be able to decide how to drive the tone detector
> knowing only the frequency of the desired tone as in the simple
> case.  The CMIB must take into account the both wideband and
> subband delay and delay rate and, I think, the mixer in the stage 2
> FIR if that is in use.
>
> Thus all the information that needs to be communicated through the
> VCI is the frequency of each tone to be detected and an integration
> time.  That information is relatively static; the polynomial
> describing the phase of the tone is unnecessary.
>
>