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Receiving and Decoding Data from an Esophageal Monitor Inside the Body

March 31, 2014 admin

Blogger Dolske has recently posted about how he was able to receive and decode signals coming from inside his body. The signals originated from a Bravo Ph Esophageal monitor which is a small wireless sensor that is attached inside your body by a doctor. It is used to monitor pH levels within the body to help diagnose esophageal problems such as acid reflux. The monitor remains in the body for a number of days continually sending data to an external monitoring device which records and logs the pH data.

Bravo pH Esophageal Monitor
Bravo pH Esophageal Monitor

Using his RTL-SDR, Dolse was able to capture the wireless monitors signal using information he found about the monitor online. He found that the monitor used amplitude-shift keying and transmitted at 433.92 MHz. After capturing some signals with the RTL-SDR, he looked at the captured waveform in Audacity and was able to decode a few packets by hand. Finally, he went even further and wrote a Firefox browser based decoder which decodes and displays the pH data on screen.

Web Interface for Showing Decoded pH data from the Esophageal monitor.
Web Interface for Showing Decoded pH data from the Esophageal monitor.

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