KerberosSDR - 4 Channel Coherent RTL-SDR for direction finding, passive radar, beam forming

KerberosSDR – A 4-Channel Phase Coherent RTL-SDR for Passive Radar, Direction Finding and More!
The RTL-SDR software defined radio phenomenon has changed the world by unlocking low cost access to the radio spectrum. Whilst RTL-SDR is now a relatively mature commodity item that almost everyone whose tinkered with electronics has played with, there is still so much more potential to be unlocked.

A phase coherent RTL-SDR can be made out of two or more RTL-SDR dongles that share a common clock. With a bit of help from a noise source, the RTL-SDRs can be synced together. Once synced interesting applications become available, such as direction finding, beam forming and passive radar.

Phase coherent RTL-SDRs have been worked on and demonstrated several times over the past few years, but at RTL-SDR.com we've been disappointed to find that so far there hasn't been any easy way to replicate these experiments.

The required hardware has been difficult to build and access, and the software has been kept as unreleased closed source or has been too complicated to install and use.