Sunday, 14 June 2015

Satellite Tracking / New rotor controller

(it appears I'm about due for my annual blog post entry). Those of you who follow me on twitter will be aware that I've just acquired an old Kenpro 5400 (this is roughly the same as the Yaesu G5500) Azimuth / Elevation rotator, that I plan to use to track cubesats and play with for ham radio.

On opening the control unit (I wanted to see if there were any other primary taps on the transformer, as it's a 110v controller) it was evident it had been 'altered' in the past. To quote someone on #highaltitude "that wiring job is responsible for a thousand dead kittens",

hence a plan was developed to leave the existing controller as an emergency spare and build a fresh 1U rack version instead. The ideas (such as they are) are on a github gist that I'll keep updated with plans. The rough idea being to have a decent embedded board (probably a beaglebone black as a Raspberry Pi depends on an SD card) controlling the relays for output directly, and reading in the potentiometer values to calc position. Using a more powerful microprocessor than say a pic or atmega (arduino) means I can update TLE's automatically and offload much of the tracking directly to the controller - meaning any SDR receivers can concentrate on the signal alone.

I'm also going to house in a GPS module (most likely another one from upu) so that it doubles as a stratum 1 NTP server as well as having accurate position to calculate passes from.

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