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Remote control project


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About this observation
Kevin Gurney
Time of observation
19/02/2019 - 18:15
Hardware project
Raspberry Pi
Misc. electronics components

These photos show the fruits of a recent project to allow remote
control of my MESU200 mount (with Sitech drive electronics as
supplied) and Shelyak spectroscopes (12V flats and calibration

The top panel shows the user control box with: (i) switch-based
joystick for controlling RA and DEC of the mount, (ii) button for the
speed of motion (cycles through three speeds), (iii) Toggle switches
for spectroscope flats and calibration lamps. Controls (i) and (ii)
mimic the hand-pad supplied with the MESU. This box contains an
Arduino microcontroller for encoding the switch signals and sending
them, via USB, to the 'client' computer. This can be sitting anywhere on
the local area network - in a room indoors, or the laptop near the

The bottom panel shows the 'server' computer that sits near the
scope. It contains a Raspberry pi to receive the commands (via wifi
from the client) and decode them to relays that mimic the original
(wired) hand-pad and spectroscope switches. The relays then connect
via the normal cables to the scope mount and the spectroscope.

I have tested this between my 'den' and my backyard, but it should
work across the globe in principle (albeit with some extra work to do
with IP addresses etc.)

Why did I bother to do this? First - it was a fun construction project
:). But there is a rationale...  When imaging, it is possible to frame
the object precisely by plate solving on a short exposure near the
target, 'syncing' the mount to this point, followed by a small scope
motion.  In spectroscopy this is impossible (or very hard at least)
since the image in the guide camera is unlikely to contain enough
information, and be of high enough quality, to plate solve. Precise
location of the star on the slit image is done by use of
hand-controller or a 'virtual hand-pad' in the scope control
software. Further, for imaging, you usually only visit one target per
session; in spectroscopy you might visit a few. So, aside from initial
setting up procedures, you always need to be near the scope (in the
cold!) to go to new targets. However, if remote control is possible
this is not so. I find virtual hand-pads unintuitive and clunky; even
well made button-based pads are less than ideal. The obvious choice
(as with an EQMOD X-box controller) is a joystick. Hence this

I am happy to make any details available to those who want to 'roll
their own' version of this. The software is comprised of Arduino
sketches and Python.

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