Wednesday, July 11, 2012

Portable SDR with Olinuxino for Tracking Wildlife

I was working on a project for a biologist friend of mine, that involved tracking RF tag implants on wildlife, using an SDR DVB-T dongle. He wanted a portable solution to be placed near the sprainting places of Otters(Lutra lutra), the main subject of the study, where they regularly come to deposit scent marks.

An RF tag is implanted on the animal which sends pulses on a frequency unique for each tag, this way we're able to tell them apart, this is what a cheap RF tag looks like,  this one has a frequency of 148.354Mhz
Software defined radio (SDR) became a bit more accessible recently, when a kernel hacker discovered that DVB-T dongles based on the RTL2832U chip can be used as a cheap SDR, since the chip allows transferring the raw samples to the host. Since the project was on a tight budget that seemed like a perfect solution...

The osmocom project provides a user space driver for the dongle, I started with pyrtlsdr, a Python binding for librtlsdr, and pylab for signal processing of the samples collected by the SDR, to compute and plot the PSD, that last spike corresponds to the signal of the RF tag above:

Finally, I ported everything to an olinuxino ARM-based board running Linux, a script runs on boot and logs the detected frequencies to file on SD card for later processing, the board still hasn't been tested in the field yet, I'm still working out some issues with the power management.


  1. hi, nice work. What linux and python installation do you use on the olinuxino?
    Thanks in advance.

    1. Yocto BSP and I wrote the recipes for librtlsdr and pyrtlsdr