Home Made Radio Telescope

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Dundee

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Hello Troops :)
Just thought I might post my latest project.
I started this whole thing with a desire to listen to radio emissions from Jupiter.
The cunning plan :) was to re-purpose my old Satellite TV Dish, point it first at the sun and put a Sat finder on the output and use the input to the meter as the input to a small amplifier. Then, if that worked I would try the same with Jupiter.

Well fast forward a gazillion google searches and much reading and I found the Sun part would work, but I had little to no hope of receiving radio emissions from Jupiter. At least using that method. (Google project Jove for the right way)

However I did find the Open source radio astronomy project.
I have made contact with one of the founding members and she was very kind in sending links to what I need to begin making a home made radio telescope. Unfortunately the website is down at the min but I am told it will be sorted soon.

The short version is you build a Horn antenna, feed the output into a low noise amplifier, feed that into a software defined radio, and run some Perl scripts and if all goes well, Bazinga, you can pick up the Hydrogen line from space and plot the milky way and other very cool stuff.

Other than needing one more coat of paint I have finished the feed horn tonight, next is the antenna control.
There is lots of ways you can approach it but to test it I will be building a polar mount for it. So in this case you line the antenna up on the path that the stars move across the sky. Scan the antenna up and down and detect the hydrogen emissions from the milky way as the night progresses. Then reconstruct thew image later.

Here is the feed horn I finished tonight.



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So that's the start.
I was going to make the LNA but the project uses surface mount components, and although I have made lots of CT Boards over the years, I am not set up for surface mount tech. I have emailed one of the creators of the project for a plan B, but since then I have found an LNA for only about $30 online that is ready built. So I might just order one of them.

Anyway, i will post links after the video.
Here is a better description of the project than I can give.
Will keep you posted if anyone takes an interest.

Make sure you hang out till he shows the plot of the milky way, very cool.



And here is the project I am trying to copy.

 
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Dundee

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I am making the antenna control in a way that will facilitate other antennas and or dishes.
It would be very cool to pick up a signal from a Pulsar or other stuff.
The learning curve is very steep for me, but I think once I get this one completed, it will I hope make it easier to implement my cunning plan for world domination...ahem I mean look at other stuff :)
 
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Horsa

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That sounds great. It's good that you've found something fun & interesting to occupy your time with. I hope it works for you. You're so talented. :0)
 
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Dundee

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Yeah it is as much about the challenge of making it all work as anything else. I have had many days of design and ideas floating around in my head for the rotator. Think o have come up with a plan. ?
 
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Dundee

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Brilliant, Dundee! So, do you just want to map out the galaxy in radio or hoping to find LGMs?
Well initially I will be stoked if I can point it at the sun and get a Hydrogen line.
But after that...well I may pass on the little green men but would not say no to a visit from one of those blonde beauties :)
Nordics are they? Yep one can come and abduct me any time ;)
 
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Dundee

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No not quite there yet, here in OZ the cellular network is pretty close to the hydrogen line frequency. So the low noise amplifier that they recommend is from the USA and does not take that into consideration.
However I spoke to my radio mate and he gave me a link to an Aussie company that has LNA's that are designed for Australian conditions in the 21cm band with inbuilt filters to block out the cell towers. I will be ordering one tomorrow.

The second mistake I almost made is with the rota-tor.
I had this brilliant design in my head and tried to buy the bits today for it. I bought the steel but the bearings and bushes I wanted I could not find. Which was lucky as I realized I was thinking arse about.

From the ground up, my initial design was to rotate horizontally first, then the vertical was above that.
The penny dropped about 3:00pm
That will give me a lovely rotator if I mounted a cannon on it, but was never going to be a polar mount style rotator.

For that, you need the vertical rotation first, line that up with 23 degrees 26 minutes then the horizontal on top of that.
That way the rotation plane matches the tilt of the earth and the left right follows the plane.
Lol Rookie mistake, lucky I spotted my stuff up.
But I am sure you spotted my error as soon as you read it.
All is good though, I have enough steel and have the beginnings of a plan, so a bit of thought and a few diagrams and I will have a design.
To reduce the scope for errors I will test it with my camera. If I take a timed exposure and it is not blurry I have the tracking right.
If its blurry I have stuffed up.
I will control the stepper motors with an Arduino as they are baby simple to work with, and cheap.
The plan is to get the Arduino to do all the work, I send it a set of coordinates and rotation speed etc via the serial port and
It just does it. Not too hard I think. We will see soon enough.

Had some ideas about the noise floor. My son does heaps of SDR stuff (Software Designed Radio)
We found that using a PC, there is a shit ton if noise from the power grid and power supply and the PC.
We chucked the software on a laptop runniong off the battery and the noise floor dropped like a prolapse.
We then used a Raspberry PI running off a battery and it dropped again.

So once I get past the point it at the sun and see the H line in the waterfall bit.
I will mount the LNA right at the feed horn and put a battery powered Pi to record the data right behind it.
Minimize the loss.

I will reconstruct the data on the pc after a dozen hours of data is collected and hopefully have a milky way to post.

The hold up now is I cant seem to buy the mechanical stuff I need off the shelf, engineers charge $100+ per hour to make shit for me. So I decided stuff it, any nuff nuff can drill and tap a thread and weld up a mount.
So I need to buy a bit of gear and I will just make this shit myself.

Not too expensive, decent drill press, a few taps and dies.

Will keep you posted.
:)
 
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Dundee

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Me too, and the best bit is that the tech is doable, not even difficult really.
All jokes aside, I hope to get it to a stage where i am rotating a proper dish and picking up Pulsars and Planet emissions.

You, me, a spaceship, a place to bunk down...
From here to eternity baby cakes.

 
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Dundee

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Hey Oh clever one!!!
When I am working out the speed to rotate the telescope across the ecliptic.
Is the following correct?

1 rotation / day = 360 degrees
86400 seconds in a day
360 / 86400 = 0.0041666666 of a degree per second
= 0.25 minute per degree
or move it minute of ark every 4 seconds?

Is it that simple or am I missing something?

I bought a big geared wheel and a small one to drive it today
so I am just trying to sus out the math
 
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Dundee

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I am trying to work out the gearing now though, doing my head in a bit.
My drive gear has 9 teeth, the driven gear 160, I have to get another set to slow it all down. But dont want to be in a situation that one step from the stepper motor gives some absurd fractional rotation like 0.012 arc seconds.
I want to end up with one step = say 0.25 arc seconds, or something neat.

Doing my head in at the min though. I will win, I might get a few more grey hairs due to the stress, but I will win eventually :)
 

LETA

4☆babbler
Staff
Why don't you reach out to one of the scientists for some advice. Seems rather involved and non-trivial. We want pics!
 
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