Networked Radio Direction Finding with KerberosSDR and RDFMapper

We've just uploaded a short Python script to GitHub that allows radio direction bearings from a KerberosSDR to be used with the RDF Mapper software created by Jonathan Musther. RDF Mapper is a (~US$25) program that was initially written for the RDF42, a kit based doppler direction finding system. RDFMapper runs on Windows/MacOS and Linux.

KerberosSDR is our experimental 4-Tuner Coherent RTL-SDR product made in collaboration with Othernet. It can be used for applications such as radio direction finding and passive radar. Currently it's available for US$149 on the Othernet store.

The RDF Mapper software allows you to upload bearings from multiple devices distributed around a city to a public RDF server, and view all the bearings on any internet connected PC. This can allow you to quickly triangulate the location of a transmitter.

Normally you would use RDFMapper combined with an RDF42 to upload bearings, but we've written a simple script that can be used to upload bearings generated by a KerberosSDR onto the server. The RDFMapper software can then be used to visualize those bearings.

The script is based on Python, and can run directly on the Pi 3/4 or Tinkerboard that is running the KerberosSDR, or on another PC that can see the KerberosSDR bearing server if you prefer.

Instructions are available on the GitHub page. Simply set unique station names for each of your distributed units, entry your lat/lon and fixed direction bearing. Then on the RDF Mapper software open the 'Web upload/download' tab and add the unique station ID name. All the other tabs for connecting to a GPS and serial port can be ignored, as those are used for the RDF42.

This script will only work for stationary KerberosSDR units as the lat/lon is fixed. If you want to try radio direction finding in a vehicle, we recommend using our Android App for a better experience. If there is interest, we may also add support for the Android app to upload to an RDFMapper server for mobile bearing uploads. 

Notes: RDFMapper runs on the system's default browser and it needs to run in either Chrome or Firefox to work. IE does not work. It also appears that Jonathan processes orders manually, so we just want to note that there may be a delay between payment and receiving the software.

RDF Mapper Software. Data from networked units.
RDF Mapper Software. Plotting bearing data from networked units.


  1. Mike Maynard

    With a quick look at the python script, it wouldnt be very hard to add GPS capability to the script to upload the stations current position at each data point upload. At least that is, with my limited python knowledge!

    • Wil Hofman

      RDF-Mapper does accept a USB GPS unit and plot your current position on the map.
      And of course the bearing lines will be plotted from that current position.
      I often use RDF-Mapper in mobile hunts together with imported bearings from my home-base RDF station.
      (Both setups using the RDF42)

  2. Damon

    Okay, I’m going through the process of buying RDF Mapper and I realized that you mentioned it only accepts fixed GPS locations. One or more of our KerberosSDR devices will be on a car, so we need a mobile version of this. It would be great if you could add support for the KerberosSDR Android app to upload to an RDFMapper server for mobile bearing uploads.
    I’m still buying the RDF Mapper, but I would hope that Jonathon could also incorporate mobile stations in his software.

  3. Damon

    I’ve been asking for this for awhile. This is going to be amazing. I’m going to try this in the next week or so and see how well it works.
    Good going, folks!!!

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