#6 Rotor support for Orion Teletrack Az-G

[Anonymous]

The Orion Teletrack Az-G is a portable mount for small telescopes. However I believe it is strong and fast enough to be used to track LEO satellites, such as AO-51 and VO-52, using a portable antenna such as a tape measure beam or an Arrow.

There is at least one other open source program that is able to interface with the mount (http://papywizard.org). The Papywizard software directly interfaces with the mount over a serial-Bluetooth adapter, however the Skyscan AZ handheld controller that comes with the unit also includes a serial interface and the last page of the manual includes an instruction set for the serial interface. I would love to take on this project myself, but unfortunately my programming knowledge ended with Atari Basic.

Looking at the example in the manual (using the hand held controller), it may be fairly easy to send commands.

1) calculate the tracking rate desired, multiply by 4
2) convert to 2 bytes (trackrate=TrackRateHighByte*256+TrackRateLowByte)
3) send to mount in following format (all number HEX):
Positive Azm: 80, 3, 16, 6, TrackRateHighByte, TrackRateLowByte, 0, 0
Negative Azm: 80, 3, 16, 7, TrackRateHighByte, TrackRateLowByte, 0,0
Positive Alt: 80, 3, 17, 6, TrackRateHightByte, TrackRateLowByte, 0, 0
Negative Alt: 80, 3,17, 7, TrackRateHighByte, TrackRateLowByte, 0, 0

It is also possible to GET position data. I have tried manually sending commands to the mount via cutecom and it does seem to respond as I expected. Manual can be found at: http://content.telescope.com/rsc/img/catalog/product/instructions/29295.pdf

[Stéphane Fillod]

This looks like doable, and has its place in Hamlib.
Before creating a specific backend for the Orion Teletrack Az-G, do you know any open-source library offering an abstraction layer for controlling telescope rotors, so hamlib backend can be based on? That kind of library would make support broader for people into astronomy.

[Anonymous]

I don't know of a specific library, but stellarium (http://www.stellarium.org/) has the ability to control a telescope mount:
http://www.stellarium.org/wiki/index.php/Telescope_Control_plug-in

I don't think it has a driver for the Teletrack, but there are several others supported. I'll keep looking around to see if there's anything else. Also, I'll try to contact the author of Pappywizard and see if he might be willing to help.

[Anonymous]

Stellarium is able to control this telescope mount using the Celestron NexStar device driver. I am able to use the telescope plugin as well as the satellite plugin to roughly track a satellite, however it is still a very manual process (Stellarium will not continuously update object positions, so you have to press <ctrl-1> several times to keep the antenna aligned). I've tried contacting the author of the telescope plugin without success, but the source code is available at https://stellarium.svn.sourceforge.net/svnroot/stellarium/trunk/telescope_server/

[Stéphane Fillod]

IMHO, neither INDI[1] nor RTS2[2] are suitable to provide a simple abstraction layer for telescope mounts. Too bad. So I ended up writing from scratch a dedicated rotator backend for the Celestron NexStar familly of devices.

Eric, I'll need you to test this backend.
It's in the GIT repo right now, and is also available from the daily snapshot[3].
The model ID is 1401. Make sure to pass the option -vvvvv (five v's) to rotctl[4], since I'll need serial traces to help in the debug. The protocol documentation did not let me understand the elevation unit (aka declination). Please test the 'p' (get_pos) command at known elevations and send me in private the serial traces. Can you also tell me what is this full elevation range of the telescope? Hamlib expects elevation 0° to be horizon, 90° at zenith and 180° at horizon (flipped).

[1] http://www.indilib.org
[2] http://rts2.org/
[3] http://n0nb.users.sourceforge.net/
[4] http://hamlib.sourceforge.net/pdf/rotctl.1.pdf

[Nobody/Anonymous]

Hi. Eric here, formerly N3KQX, now K0JEG. I got a message on QRZ.com asking me to check out this page and try out the rotor controller. I'm happy to report that it seems to be working perfectly. I didn't see any errors using rotctld and gnome predict. It was able to track VO-52 well enough for me to pick up the Dutch beacon with it set up inside the ham shack. I will continue to test and get the information you want from the p command. I believe it does follow the rule of 0°=horizon, 90°=zenith and 180°=horizon, at least that's what it was reporting to gnome predict and just a quick visual looks like that's the case.

THANK YOU!