Oh absolutely. A simple RTL-SDR is widespread, but anything coherent is absolutely not. I mean, the Ettus 4x4 pcie card is coherent, but it's also starting at $

Oh absolutely. A simple RTL-SDR is widespread, but anything coherent is absolutely not. I mean, the Ettus 4x4 pcie card is coherent, but it's also starting at $5000 for the card. And since it's a pcie, it goes in a very non-portable computer. The KerberosSDR has one very significant disadvantage: the databus is usb2. The theoretical max is 30M samples at 8bit I and Q... And frankly we need much more bandwidth. But for a beginner foray into coherent radio applications, a KerberosSDR for $100~ is crazy worth it. Now, the older way of doing RDF (I'm a Ham, btw), was to get a handheld receiver capable of listening to the freq in question, highly directional antenna, take measurements and move. Effectively, the human with a receiver is the manual triangulator which can be trained with experience. That was because gear that did triangulation was $$$$$$.