Low-cost multichannel radio direction finding system based on software-defined radio

A radio direction finding (RDF) system to find line-of-bearing (LOB) towards communication used by nefarious actors may be a useful tool for illegal boat activity detection. Crews of boats involved in illegal activities, such as smuggling, may communicate with their accomplices on other boats or land using various RF communication systems with different frequencies. The Citizen Band (CB) radios have less of a chance to be intercepted by Electronic Intelligence (ELINT) and direction finding used by the USCG than VHF, UHF two-way radios. Also, 27 MHz GPS buoys are used by smugglers to tag packages left afloat in open water to be picked up by an accomplice. To detect such activity RDF system should be able to detect transmissions that are: distant, few, and short and occurring on any channel. The system should support installation on a vehicle or a boat for mobility. Stevens Institute of Technology has developed and tested a low-cost RDF system, that is capable of simultaneous direction-finding towards distant transmissions with simultaneous detection on multiple channels based on software-defined radio (SDR) and pseudo-doppler (PD) principles of direction-finding. Software with a user-friendly interface has been developed to process, display results, and integrate with mapping systems in real-time. The same approach can be used for RDF working in the other frequency bands.