[evla-sw-discuss] Delay models to station boards

[Ken Sowinski]

On Wed, 21 May 2008, Barry Clark wrote:

I can answer some of these questions based on existing station board
code that digests the delay polynomials and regurgitates to the
hardware registers.

> The units of the coefficients should be stated in the documentation.
> I'm not sure what units you are expecting but something like microseconds,
> microseconds per day, microseconds per day per day make nice readable
> numbers.  Clocks instead of microseconds is still pretty reasonable,
> but clocks per clock is annoyingly small.

The existing code is expecting seconds, seconds/second, etc.  It
is easy to change we just need agreement.  The translation to clocks
and seconds/clock is taken care of on the station board and depends
on things that the polynomial creator probably does not want to know.

> Similarly a documentatin matter - are the sbDelayModel coefficients
> ab initio or as an offset from the bbDelayModel?  (if the latter,
> floats are adequate.)

The current code, and Brent's programmers manual, expects these to
be offsets from the wideband delays polynomial.  Units are the same
as for the wideband delay.  I doubt that the higher order terms will
ever be perceptibly different from 0.0.