Make a Radio Telescope With Raspberry Pi

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About: I am a hobbyist who likes space and electronics.

It is really easy to get an optical telescope. You can just buy one from a manufacturer of such telescopes. However, the same cannot really be said of radio telescopes. Usually, you have to make them yourself. In this Instructable, I will show how to build a radio telescope.

Step 1: Getting the Parts

In order to make this radio telescope, first, you will need to get the parts for it.

You will also need appropriate software in order to use the radio telescope. You need to have downloaded onto the Raspberry Pi Raspbian, which should include Python 3, and the Python library for the ADS1115.

For your smartphone, you will want to use a satellite tracking app in order to discern between satellites and stellar objects, and a star tracking app to know where celestial objects are in the sky.

Step 2: Hardware

Follow the diagram and pictures shown in making the electronics for the radio telescope.

The wires going to the dial of the finder should be disconnected from the dial. The ground connection of the ADS1115 connects to the ground pin that leads to the dial, and the analog input should be connected to the other wire.

On the dish itself, a nylon washer should be placed between the nut and the backup support.

Step 3: Software

In order to read and store the data, the Raspberry Pi and the ADS1115 come into play. Any Raspberry Pi with the latest version of Raspbian can do. The instructions for the software library are in the PDF on the Adafruit website. Before downloading, you must set Python 3 as the default Python. In order to check, type into terminal

python --version

If you get a response that reads Python 3.x.x, the default Python version is Python 3, and you do not need to change the default Python version. However, if your default version is version 2, you will have to change it by going into terminal and typing in

sudo update-alternatives --config python

Then, press 0 to select Python 3 as the default version. Once you have downloaded the Python library, you can download the code for using the radio telescope. On the Raspberry Pi, create a folder in /home/pi called radio_telescope_files. You should of course have standard peripherals for a Raspberry Pi, such as keyboard, mouse, and monitor. If you have the Raspberry Pi Zero without GPIO pins, you will have to solder them yourself. You will also have to solder the pins on the ADS1115 breakout board.

Step 4: Short Tests

Once you have the appropriate software on the Pi, and all the pins soldered on, you can connect the breakout board to the Raspberry Pi. In order to do so, put the pins of the board into a breadboard. The VDD pin should be connected to a 3.3-volt or 5-volt pin on the Raspberry Pi, GND to any ground pin on the Pi, SCL to pin 5 on the Pi, which is SCL, and SDA to pin 3, or SDA, on the Pi. Once the ADS1115 is connected to the Pi, you can now connect the green wire of the modified Finder to A0 on the ADS1115, and the black wire to GND on the board. If it suits you better, you can connect the respective wires by attaching an alligator clip wire to the wire, and a jumper wire to the other end, connecting to the respective board connection. Then, connect the LNB to the input on the Finder by coaxial cable. Plug the power cable into the barrel jack to turn the finder on.

In order to test the Radio telescope, point the dish at such as the sun, the strongest emitter of radio waves from our perspective on Earth. In order to do so, point the dish towards the sun so that the top of the shadow of the LNB hits where the LNB arm meets the dish. Now, turn your Raspberry Pi on and run toScreen.py, the Python script for reading results from the ADS1115 and printing them on screen. You can run this in either the Python 3 IDLE, or terminal. Either way, you should get a prompt asking for the gain, followed by the sample rate, and how long you want the Pi to read the ADS1115’s output. With your dish pointed at the sun, run the script for about 10 seconds. If very low numbers initially shows up, turn the gain knob on the Finder up, very slowly. The numbers should increase until it reaches about 30700. By then, you can stop turning the knob.

Step 5: Saving Results

toScreen.py is a good way to test the radio telescope, but it does not store data. writeToFile.py can store the data, and you can run this in the same way in IDLE and terminal. This script stores data in a text file, which should be found in the folder named ‘Data.’ If you run this, it will ask for the gain, the sample rate, what duration of time you want the Pi to read the ADC, and the name of the file in which you store this data. The radio telescope will pick up the radio signal strength at points throughout the time the radio telescope has been scanning the sky will be stored in the Raspberry Pi.

After collecting the data, it can be graphed in a spreadsheet program, by first getting the timestamps of the data, putting them in column A, then getting the data, and putting them in column B. This can be achieved by using the column.py script. To get the timestamps, run the script, then enter time for the message asking which to read, the timestamps or the data values. In reading the graph, it is important to know that the leftmost point on it represents the westernmost point in the sky that was scanned.

Step 6: Further Use

The radio telescope can be used for observing not just the sun, but other celestial objects such as stars, using the same method as used for the sun. If you have any questions, comments or concerns, let me know in the comments.

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    19 Discussions

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    morgan1020

    Question 13 days ago

    Hello! I am trying to build this telescope and I have a few questions!

    1) I am omitting the satellite finder, and I am trying to read your circuit diagram. What is the box, with the round object on it connected to the finder and the power supply? Is this denoting the DC barrel jack?

    2) How is the system powered? Is it just the LNB being connected to power supply?

    Thank you for any answers and an awesome idea!

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    graham129812

    Question 7 weeks ago on Step 1

    Greetings. Where did you put the RF choke. I don’t see it mentioned in the text and can’t tell from the photos. Will you let me know? Thanks!

    1 answer
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    ElectricSpacegraham129812

    Reply 7 weeks ago

    The RF choke should be located on the +15 V red wire going to the satellite finder.

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    mustang247

    Question 10 months ago on Step 3

    Good day. Can this be hooked up to a laptop instead of smartphone?

    1 answer
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    ElectricSpacemustang247

    Reply 10 months ago

    It can be hooked up to a laptop instead of a Raspberry Pi, if you can get it to work with the ADS1115 or another Analog to Digital Converter.

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    ElectricSpaceJeffreyM108

    Reply 10 months ago

    Yes, if you can get the Arduino, or any microcontroller or computer working with the ADS1115, it would work.

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    fred_

    Question 10 months ago

    Any plans to add some pan and tilt steppers/servos and scan a region for imaging?

    1 answer
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    Nyxius

    Question 10 months ago on Step 6

    So this is essentially a 1 dimensional telescope? As opposed to the 2 d sensor matrix of the typical CCD?

    4 answers
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    ElectricSpaceNyxius

    Reply 10 months ago

    Yes, as it can scan radio signal strength in a line when it is left to scan the sky for a while. However, if you are able to scan the sky directly under or over the part of the sky already scanned, it is possible to make a 2D radio image, but it would be difficult.

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    NyxiusElectricSpace

    Reply 10 months ago

    The sensor is at the focal point of the dish right?

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    NyxiusElectricSpace

    Reply 10 months ago

    Since the sensor is in the focal plane, and the focal plane image is the 2d Fourier transform of the spacial image, couldn't you move the sensor slightly on a DVD drive rail in the focal plane to image the 2d domain Fourier image? Then one can apply a specific solution inverse Fourier transform to create a real image.

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    paulhurm

    10 months ago

    Have you had any luck yet with observing an actual celestial object such as Cas A?

    1 reply
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    MR_Huns

    10 months ago

    Absolutely brilliant! The natural progression from SDR. I knew it would be harder than Charlie Sheen made it look in The Arrival, but I had no idea it was this easy. Thank you so much. I'm totally going to put it on my to make list.

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    Swansong

    10 months ago

    That's a neat setup to track celestial bodies :) It'd be an awesome tool to have in an astronomy class!