04-Feb-1995 / MCBA--Software changes:
- The CCD readout code has been entirely overhauled to improve
reliability and increase speed. As a result, the entire chip can be
read out in high-speed mode in 6 seconds (used to be 10) and in low-speed
mode in 34 seconds (used to be 38).
- Exposures now start immediately after executing the "exp"
command--they used to wait about 3 seconds, and were synchronised
to the PC seconds-clock.
- Exposure timing has been improved, eliminating one cause of the
program crashing.
- The focus stepper motor speed has been reduced, to avoid the
problem of missing steps which has occurred recently. A new command,
``focus delay xxx'' has been added so that users can change the
speed--the number xxx is the delay in microseconds between
steps.
- A new command, ``move peak x y'' will move the
telescope so that the brightest single pixel in the most recent
image processed with ``stats'' or ``readstats'' is moved to coordinate
x y on the CCD. This command is expected to be very useful for
automatically calibrating the telescope, and in assisting the registration
of images.
- A better algorithm has been incorporated for detecting the
completion of a telescope slew. This is not easy, due to the unreliability
of the information returned by the Apple II. The slew wait can now
be interrupted more easily by hitting a key on the keyboard.
- The statistics area on the CCD can now be set to a subset of the
image readout area, which means that it is possible to use the ``readstats''
command with negligible time overhead if only a small area is being
used for statistics (as is the case for estimating flat-field exposures).
- Communication between the PC and the workstation has been improved.
The link will now be re-established more rapidly if it goes down.
The focus motor controller has had low-pass filtering installed on the
inputs from the PC; this has fixed the problem whereby the controller
would spontaneously reset or issue pulses when a power spike occurred
on the mains.
An Uninterruptible Power Supply (UPS) has been brought up from Sydney,
as has a revised version of a servo amplifier. Neither has been tested,
so please don't use them yet.