The information security community has long suffered from a lack of effective and affordable tools and techniques for locating radio devices. Many methods are available, but most of them require multiple radio receivers and/or physical motion of one or more antennas. Pseudo-doppler is an old technique that implements Direction Finding (DF) by rapidly switching between multiple fixed antennas connected to a single radio receiver.
We have taken a modern approach to the implementation of pseudo-doppler DF with Software Defined Radio (SDR). Our open source solution enables low cost DF of bursty, packet-based target systems using arbitrary digital modulations. Additionally we will discuss our future work toward asymmetric pseudo-doppler approaches that eliminate the need for direction calibration and that can be used as a countermeasure against targets that attempt to spoof direction.