One thing that I wanted to do this week was to validate the effect of including frequency diversity in the network that we made for our robots. So, I programmed one ESP32 feather board with a 433 MHz packet radio on its stack to send out a lot of garbage values over the 433 MHz band extremely quickly. I wanted to see if having that much noise on the band would prevent our nodes from talking over 433 MHz.

To test this, I set up two nodes to talk to each other, and printed out the delay times between them to the dashboard. Then, I plugged in the jammer that I made. Immediately, all messages that were being sent between nodes were only being received over the network on 2.4 GHz / Wifi. After I unplugged the jammer, both frequencies were usable once again.

To visually demonstrate the robustness that frequency diversity provides our system, I made all nodes use their LED screen to determine when they received messages as well as what frequencies the messages were received over. When a node receives a message over 433 MHz, the LED screen lights up orange, and for 2.4 GHz it lights up blue; furthermore, when the message is received over both frequencies, the colors combine to make a white-purple. Then, after a second since the last received message, the LED board resets.

Here is a video of me plugging in the 433 MHz jammer to demonstrate the frequency diversity display on the LED. As you can see, the inclusion of both 2.4 GHz and 433 MHz in our network infrastructure allows us to successfully communicate between nodes despite obstacles that arise on one frequency.

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