Hi SatNOGS team,
First of all congratulations for the good work you guys (m/f) are doing!
I am currently investigating the construction of my own base station. Like everyone else I have my own set of specific constraints (money being an important one), so I’ll be building a modified version of the station based on the standard you developed. Before I commit I’d like to run some of my thoughts by you to make sure what I am attempting to do sounds reasonable. Prepare for a somewhat lengthy post with quite a few questions.
- Hardware design
I am looking at building a V3 design. Would this be the recommended design to build (mature, proven)?
I read about digital/analogue pots for indexing the movement of the axis. As I don’t see them included in the documentation yet, I am assuming this is a work in progress and the current version indexes its position by counting steps and occasionally homing the system using the end stop sensors?
- Metalwork vs 3D-printing
I have more skills in metalworking than in 3D printing, so I’m looking to fabricate most of the hardware instead of printing it. One exception being the worm gear/axis gear combination. Since I don’t have access to a mill, 3D printing would make more sense than attempting to cobble up something in metal. I will attempt to arrange access to a fablab to print 2 sets for me.
https://github.com/satnogs/satnogs-rotator/blob/master/axis_gear.stl
https://github.com/satnogs/satnogs-rotator/blob/master/worm_gear.stl
Would there be other parts where you would recommend printing over fabricating?
- Electronics
What would be the best version to build? I am assuming this one: /satnogs-rotator-controller/tree/v1 ? Although I am proficient at etching PCBs at home, perhaps someone is interested in selling some spare PCBs?
Where do you guys get the Polulu drivers and the PSU converter? If I order from Polulu there is a substantial shipping cost, I wonder if eBay knock-offs are an option (if so, links appreciated)?
- Controller
I see you support both the Raspi and the BeagleBone Black. I am leaning towards the Raspi2 because it’s cheaper and I have experience with it. If that would be a mistake because of support, processing power or other reasons then I’d like to hear about it. A 25€ difference isn’t worth getting stuck on Raspi island if all the rest of you are living on the BeagleBone continent 
- Antennas & receivers
For now I plan to mount a simple laser pointer on the tracking system and attempt to track the ISS with it. Since the ISS is the brightest object in the sky, pointing a laser at it would IMHO be a good way to test-drive the system. Of course I don’t plan to leave the laser on all the time, just occasionally send a brief pulse so I can test if the system is tracking correctly.
Thanks in advance,
David
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