Whether you are tracking down a stuck transmitter keying up a local repeater, hunting for a rouge interference source, or competing in a club foxhunt, Radio Direction Finding or "RDF" is one of the most practical and fun skills in radio.
Signal hunting relies on manual triangulation using hand held directional antennas, like a yagi. While effective, manual hunting takes time and requires sweeping multiple vectors. Modern Software Defined Radio technology has introduced a game-changer: phase-coherent radio direction finding using the KrakenSDR.
The Mohave Area Repeater Club is excited to announce that we've acquired a KrakenSDR system and have deployed it several times in real world and training scenarios. This powerful tool brings high-precision radio direction finding and automated signal hunting to our local GMRS & Armature Radio community. To support field training, emergency response efforts, and fox hunting across the region, MohaveARC is making the KrakenSDR available for use by radio clubs in the region. Whether you're running a fox hunt for training or tracking down harmful interference, reach out to us via the contact page to learn how you can deploy the unit.
What Makes the KrakenSDR Different?
Most standard SDRs, like a single RTL-SDR dongle, process RF signals through a single channel. To determine a signal's line of bearing in real time, you need multiple receivers operating on the exact same clock and local oscillator, a property known as phase coherence.
The KrakenSDR combines five rtl-sdr receivers onto a single board, synchronized with a shared clock and an internal noise source for automatic phase calibration.
Accuracy in the real world
Real-world testing shows that the KrakenSDR achieves an accuracy of about 30 meters in a Uniform Circular Array (UCA) configuration, and down to 10 meters with a Linear Array. Getting within that 10 to 30 meter radius is crucial when narrowing a signal down to a specific property or vehicle. In fact, during initial testing, the KrakenSDR alone was precise enough to tell us which side of a house the transmitter was on.
While the SDR excels at rapidly getting us into the immediate area, pairing its digital bearings with traditional direction-finding tools, like directional loop or Yagi antennas paired with near-field attenuation is what allows us to zero in on the exact physical spot.
Kraken Antenna Array
Precise spacing and length is everything when it comes to KrakenSDR antenna placement. Pictured here is a 5-element Uniform Circular Array mounted on a member's vehicle, tuned for maximum accuracy.
Kraken SDR In Action
We recorded a short demo of the KrakenSDR software while going head to head with some veteran hams from the Hualapai Armature Radio Club in a Fox Hunt. It wouldn't be fair to call it a fair race though. As you'll see in the video, the KrakenSDR gave us turn by turn directions straight to the transmitter.