Thursday, 23 May 2013

Radio Astronomy Station. Part 1.

Whats All This?
I've worked on a few big projects in my life. Mostly as a result of companies I've worked for. I'm not talking 'Death Star' sized projects but the kind of thing you can really get your teeth into and come out the other side feeling exhilarated and the sense of achievement.

I plan to cover the development of a Radio Astronomy station using pretty much off-the-shelf hardware so that capable readers of this blog could quite easily follow instructions and put one together themselves.

Radio Astronomy by the numbers
For the average tech type person this project will involve a number of steps.
  1. Set up a PC with Windows 7. Install the 'Radio Eyes' and 'Skypipe' Radio Astronomy applications. Install a 'Driver' program to talk to the positioning system. This computer will be located near the Dish.
  2. Set up a Raspberry Pi computer running 'Raspbian' operating system. Install the driver software to receive radio signals with it using a DVB USB stick that has an RTL2832 and E4000 devices in it.
  3. Program an Arduino Uno controller board with a Real Time Clock and a L298 H-Bridge motor driver to position the dish.
  4. Set up a C-Band 2.4 meter dish antenna with Elevation and Azimuth motors. Mount the Raspberry Pi and DVB Software Defined receiver at the dish focal point.

The blog is going to detail the above steps and the software for the system will be available free to download except for 'Radio Eyes' and 'Skypipe' which are available through RadioSky Publishing

Putting It Together
Look around for a good sized mesh type C-Band satellite dish. You can find them on Ebay quite cheaply. You'll probably want a good sized pole to mount the dish with as well. Maybe 75mm diameter and 2 meters in length. Depending where you mount this you'll want half a meter in the ground and concreted in. If the soil is soft you may want it deeper. Stability is of utmost importance. Think about adding struts if the pole moves at all.
You should end up with the dish mount at about head height. This makes it easier to work on. An actuator will be mounted under the dish in order to give elevation drive. This should be able to swing the dish from 0 degrees up to 90 degrees. Actuators can be driven with 12, 24 or 36 volts depending on the type available to you. Actuators have two motor wires, usually RED and BLACK. They will also have two sensor wires connected to a reed switch inside the actuator that 'pulses' as the actuator drives the arm in or out.

This is a picture of the 2.4 meter 'JoySky' dish that I am using.

In the next post I'll put up a block diagram of what I'm building so you can get a better idea of how it all goes together.

Cheers 'till then.