hacker

wilho

PiRotator

RaspberryPi controlled antenna rotator

Summary:

Current commercial az/el antenna rotators are really expensive(easily over 1500€ with controllers), and moreover technically most are from 90s (analog potentiometer sensors/control, no network, rs/lpt controllable, no web, no rest api, etc).

I tried to take little bit different approach..

Goals:

• Cheap common hardware (wormgears, nema steppers, rasberrypi, etc)
• Intelligence on mast (controlbox includes rasberrypi, this enables many things, like SDR on mast)
• All digital (digital rotary sensors, steppers, tcp/ip, etc)
• network (only IO is network, controlling thru different apis(REST, legacy RS emulation api))
• backward compatibility to legacy software, via software RS (ham radio deluxe, pstrotator, etc)
• project is only for fun, and learning new stuff!

Hardware:

• Steppers:
  • Common 4-lead NEMA 23
  • one full step 1.8 degrees
  • cheap (from 10$/each)
  • easy to control
• Worm gears:

  • 90 degree Gearbox ?WormGear Speed Reducer 1:60 ratio

  • most important is ?WormGear, because of that we do not need any brake system!

  • relatively sheap (about 50$ / each)

  • with 1:60 reduction we do not need that much power and precision is 1.8 (from step) / 60 -> 0.03angle /step

• Absolute rotary encoders:
  • Cheapest used 10bit absolute rotary sensors what i could find (KOYO TRD-3A1024)

  • precision is more than enough (10bit -> 1024 -> 360/1024= 0.35 degrees)

  • price about 15€/each
  • 10bit means on this case that there are 10pin for data + 2 power pins
• Slip rings:

  • https://en.wikipedia.org/wiki/Slip_ring

  • Capsule slip ring OD22MM 18Wires
  • stepper control cables and rotary sensors data cables to upper module go thru axle, with slip ring we dont have to worry about these cables and rotation.
  • about 15€
• Stepper control:

  • https://www.piborg.org/picoborgrev

  • ?PicoBorg Reverse

  • easy, cheap, efficient,
• Controller:
  • Raspberrypi 2 or B+
  • full OS
  • enough gpio ports for encoders and stepper control
  • network port
  • could run as "SDR streamer" with rtl_tcp or similar
  • full python
• Connectors/box/cables/gears/belts/bolts/etc:

Software:

Plan / specs for pirotator server:

• REST api for controlling (done)
  • you could control your rotator via simple http posts
  • enables many kind of solutions
• Legacy rotator emulation for legacy software via virtual RS (done)
  • emulates yeasu GS-232B protocol (only control and feedback commands implemented)

  • client OS sees ?SerialPort via virtual serial port software (eg. hw-groups HW virtual serial port -HW VSP3)

  • Tested with HRD rotator and PSTrotator
• Simpple CLI UI (70%)
  • mainly for debugging purposes
• Multithreaded structure, and locks/aborts (90%)
  • could use all of those apis/interfaces at same time
• Neat WEB/JavaScript UI top of REST api (15%)
  • Graphical javascipt / angular UI

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