The tiny radio telescope

Big milestone reached! We actually managed to hook up the RTL-SDR dongle to the LNB with the inline signal booster too!

As a simple test, I tuned it to a local radio station...

Finally! Some progress! Our RF coax F type cable to MCX connector has now arrived! We can now attach the RTL-SDR dongle to the satellite dish!

The sterling gentlemen at our local cycle shop (Linden Cycle) donated 2 old bicycle wheels for our project. They also threw in a cog and a derailleur sprocket for a spiffy 3:1 gear ratio.

The idea is to weld the spoked aluminium wheel to the lazy susan turntable top, with the big cog in between. A bicycle chain to a stepper motor will then rotate it, giving up a pretty sweet azimuth system, controlled by a stepper driver and a microcontroller.

The altitude system will work similarly, just a touch worried about getting enogh holding torque for it to be useful!

With the basic components here, we have managed a first successful test! This test officially puts us on par with the NRAO "Itty bitty" project!

Check out the pics for the "data" :)

First off, we pointed the dish (and attached LNB) to some relatively open sky. Unfortunately, I live in a townhouse complex, so open sky is a bit of a commodity here (hence the small reading). This was to calibrate the LNB to get a baseline "0" reading.

We then pointed the LNB near the sun.

Immediately the satellite finder lit up like a Christmas tree and gave us a much stronger reading. This is quite expected as the sun is a very strong RF source. I also pointed it at IS20 (found via a mobile Android app, and eyeballing where our regular TV satellite dish was pointing) and got about the same reading.

After about a minute, the sun started passing out of the dish line of sight, and the following reading was taken

This is great confirmation that, at least, the components are all working! I hacked an LNB power supply from an old Set Top Box that I had lying about (a proper one is on order, waiting for delivery).

Altogether, a great morning's work! Very pleased with the results!

We have finally taken delivery of a satellite meter! This will aid us greatly in aiming the dish at objects, as well as with testing that everything is working correctly!

Using an Android driver and RF analyzer app, we have now confirmed that the RTL-SDR dongle is, in fact, working correctly. This may be my last log for a while now, as we are waiting on delivery of the satellite LNB components. I had to order out of country for a powered multiswitch, as well as a heavy duty lazy susan for the base. Good thing though, is that the lazy susan is rated at 300 lb's so that should be good enough.

I will now also start designing the worm screw based altitude base, and figuring out any bugs with that too. I am unsure if I will go with the worm screw design, as I may decide to do a pair of stepper motors with LEGO tyres on them on a semicircular blade like design. Much in the same way that fairground roller coasters and things work with spinning tyres to accelerate the thing. Hopefully there will be enough grip to do it that way, as we will then be able to take full advantage of the 200 steps/rev on the steppers.

Enlisted the help of my kids to get the satellite dish prepared this weekend. It is now rust free, painted and ready to go!

Getting all that rust off!

Corgi work inspector...

Done, and passed final Corgi inspection.

Managed to get hold of an inline signal booster (line amplifier) at a local satellite TV shop. Relatively inexpensive and hopefully will make a huge impact on what we can detect!

Designed and ready to print. I am not yet sure that the gear ratio will be high enough for a NEMA 17 stepper motor to drive it, but I suspect it should be OK. The antenna is not very heavy, but I am a little worried about possible wind damage....

I managed to find a 1m satellite dish on OLX for only R200! Sweet!