Destructive Interference with ADS-B

I did a quick destructive interference extension to my ADS-B ongoing project. Take a look!


Interference is what happens when two signals with different amplitudes combine. Due to the theory of superposition, the wave’s amplitudes can be added on top of each other. Destructive Interference specifically happens when one signal has a negative amplitude compared to the other; when the amplitudes add, they subtract off of the total amplitude.


My code is a simple extension of last week’s matlab solution. I found my approximate packet, and reversed the amplitude of each signal. It can be identified below:

reverse_packet = -packet1;    
reverse_array{i} = reverse_packet;
new_signal = packet1+reverse_packet;
signal_array{i} = new_signal;

This code also takes both the inverse signal and the summed signal (should be a string of 0’s) and saves it into an array.


In a finite-time script like I have (reading from a data file not in real time), I am able to create inverse values for all of my packets. To visualize them I pick random strings and present their inverse values. The wave output should be 0 here:

for i=1:4
r = randi(length(packet_starts1));
hold on
ylim = ([-1.1, 1.1]);
legend('Incoming ADS-B Packet','Destructive Signal')
title('Destructive Interference ADS-B Packet')
ylabel('Relative Amplitude')
hold off

Visualized Random Results

Extension and Application

In matlab this code works well, but I eventually want to port this over to python or GNUradio for real-time use. I plan on using a peak detector block for rapid destructive interference.

Hope you enjoyed the relatively short write-up! Expect more on much diverse topics (like propagation modeling) in the future.