Tuning Into Medical Implants With The RTL-SDR

With a little luck, you will live your whole life without the need for an implanted medical device. But if you do you end up with the news that your doctor will install an active transmitter in your body, you may break the software-defined radio (SDR) and see if you can decode its transmission as [James Wu] did it recently.

Before the Medtronic Bravo Reflux capsule is attached to the lower part of the esophagus, [James] you took a good look at the pencil-width gadget demonstration unit. Although the medical technician told him that the device used a “Bluetooth-like” communication protocol to transmit the pH of his esophagus to a wearable receiver, the large 433 placed on the hardware made him think it was worth taking a closer look at the documentation. Of course, its entry into the FCC database not only confirmed that the radio transmitted a 433.92 MHz encoded OOK-PWM signal, but even broke the contents of each packet. If only it was always that easy, right?

In the end, 433 was a coincidence, but it got him on the right track.

Of course, he still had to put this information into practice, so the next step was to create a configuration file for the popular rtl_433 a program that divides each package into its main parts. This part of the recording is especially interesting for those who may want to download data from their own 433 MHz sensors, medical or otherwise

Unfortunately, one piece of the puzzle was still missing. He knew which field was the pH value from the FCC database, but the 16-bit integer he was getting didn’t make any sense. After several more hardware studies that revealed another attempt to decode transmissions from the early days of the RTL-SDR project, he realized what he actually saw was a combination of two 8-bit pH measurements being sent simultaneously.

We were pleasantly surprised to see how much public information [James] managed to find out about the Medtronic Bravo Reflux capsule, but in a perfect world this would be the norm. You deserve to know everything you need to know about some of the electronics that will be placed in your body, but for now movement to open hardware medical devices struggles to gain a lot of traction.