[evlatests] Set-and-Remember Failures

[Ken Sowinski]

On Sat, 21 Jan 2012, Rick Perley wrote:

>    This raises a question:  Since it is clear from the data that the
> correct power level is in general determined with ~5 seconds, why does
> it take so long for the system to 'remember' this?
>     Finally:  I'm not likely to be the last person to want short
> observations with a long script.  Assuming that we'll never be able to
> guarantee long scripts running successfully with requiring a restart, is
> there a way to remember the appropriate level settings from the earlier
> portion, or to ensure that the initial scans on any script be extended
> long enough for these settings to be remembered?

One way to achieve this is to use the 'preamble' feature 
of the executor to execute a script fragment before the
real observing starts.

For eight-bit samplers setting downconverter attenuators
once is adequate.  When we address the use of three-bit
samplers we will probably want a way to re-set the
attenuators over time for a very long observation.

In both cases we will eventually need to think about when and
how to adjust the requantizer gain knob in the correlator.