Did you know that ATC conversations and conversations between planes are freely available, with no encryption? It is legal to listen in on ATC conversations, and in this guide I will tell you how if you have some free time.
What You Need
RTL-SDR Stick and Antenna (x1)
This is the antenna and radio processor we will be using to get a signal from an air traffic control tower.
SDRSharp by Airspy
This is the program that we will be using to listen to these conversations and to tune the antenna.
Initial Setup
If it is your first time using SDR# (SDRSharp), then you must install SDR#, then install the drivers. The below guide will show you how to do so.
First, install SDR# and let the installation wizard guide you through the process.
Then, open the newly added program Zadig and you should see a screen like the one below.
- A: This is where you choose the interface you want to install drivers for
- B: This is where you check if a driver was installed
- C: This is where you can install the drivers
Follow the steps below:
- First, use dropdown A to select an interface. The interface must start with Bulk-in, Interface. If you have multiple bulk-in interfaces, repeat these steps for every one
- Next, make sure textbox B tells you that there is no driver installed
- Finally, click Install WCID Driver (button C)
Opening SDR#
Once all the drivers are installed, you may close out of Zadig and open SDR#. You should see a screen like the one below.
- A: This is the frequency selector. This is where you can choose which frequency your antenna is supposed to be tuned to. Right now it is tuned to 120 MHz, but in the next section you will learn to find the frequency of your ATC tower
- B: This is where you can choose your radio settings. For this tutorial, keep the default settings but change the radio mode to AM
- C: This is where you choose the source of the radio stream. Right now you want it set to RTL-SDR USB
- D: This is where you can visualize the radio waves. You can click anywhere on this to set the frequency to the location of the waves to which you clicked. You can drag the lighter waves to set the bandwidth. You want to make sure that the bandwidth is not too big otherwise you will get interference, but not too small so you only get part of the wave. I have set my bandwidth to 7.557 kHz
Reading Aerospace Vector Maps
Using a site, like SkyVector, you can find your airport and look at the frequency under it. Tune to that frequency. For place value context, think of the second segment of numbers as MHz SkyVector shows frequencies in megahertz.
Some airports, like the ones marked with a star, do not have full-time ATC, meaning that planes have to talk directly to each other.
Tune to this frequency on SDR#.
Listening to these frequencies
Look for any spikes in these frequencies. Ste the frequency to the frequency of these spikes (you can do this easily by clicking on these spikes) Adjust the bandwidth to these spikes, hovering over the top-right Zoom button and using the slider below it to zoom into the waves. Click on the top-left gear icon and adjust the setting to match the ones below:
Now, turn the volume up and listen. If you do not hear talking, experiment with the bandwidth or choose another frequency. A good frequency should be like the one below:
Done!
And that is the end of the project! Pretty easy, right? There are some caveats, though. You will only get the best signal when you live no further than 50 kilometers away from an airport with a full-time ATC, and the radio tends to disconnect a lot if not screwed in fully. Either way, it is still a super cool project, and is definitely worth trying out if you are interested in this kind of thing. Frequencies might not be exact, so experiment a little!