This is still incredibly DF-able, as well as RF fingerprinting of the transmitter.
I'd be very interested in an SDR application which strove for undetectable communications, either super high chirp rate FHSS or UWB.
In practice, you're probably best off by masquerading as another communications technology and hiding your traffic within that, rather than trying to use long-haul broadcast RF to hide your location. A common technique if you do need to radiate a lot of RF and don't want to be DF'd is to remote the transmitter from yourself over some other protocol -- a separate point to point radio link, or stored communications, or an IP/PSTN/etc. link. This is how a lot of pirate radios, military radios and radars, etc. work -- the emitter is at risk, but as long as you can break the link between emitter and controller, that's not the end of the world.
I'd be very interested in an SDR application which strove for undetectable communications, either super high chirp rate FHSS or UWB.
In practice, you're probably best off by masquerading as another communications technology and hiding your traffic within that, rather than trying to use long-haul broadcast RF to hide your location. A common technique if you do need to radiate a lot of RF and don't want to be DF'd is to remote the transmitter from yourself over some other protocol -- a separate point to point radio link, or stored communications, or an IP/PSTN/etc. link. This is how a lot of pirate radios, military radios and radars, etc. work -- the emitter is at risk, but as long as you can break the link between emitter and controller, that's not the end of the world.