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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