Shutter timing

[Chris Albertson <calbertson@logicon.com>]

Tom writes,

> Also per the notes, this does not guarantee that all images
> are of comparable length.

Tom,

I know about your problem with serial port timing.  One thing I
am doing that you could maybe do in your BASIC software is to
record the _actual_ times.  In other words you capture the wall
clock time just after the shutter opens and just after it closes
even if the open and close times get messed up by the OS.  So the
final FITS files header would record the actual rather then intended
exposure time.  This would likely only require a few small mods to
both your QBASIC program and to the raw-to-fits program. (I'd
suggest the QBASIC program would write out any housekeeping data
after the pixel array.)

My Linux based software will record the time (of day) when the STAMP
sends an ACK.  I am designing things so that the software is "ACK
driven".  The Linux software can queue up STAMP commands far faster
then the serial link could deliver them.  My serial port handler
queues outbound commands at any time and issues them to the STAMP
whenever the STAMP sends an ACK or a power up version message.


-- 
  Chris Albertson

  calbertson@logicon.com                  Voice: 626-351-0089  x17
  Logicon, Pasadena California            Fax:   626-351-0699