usna.navy.mil: APRS Direction Finding Citat: "...One of the most useful tactical local tools of APRS is Signal location and Direction finding. Since APRS can locate signal sources based simply on SIGNAL strength, it is far superior than other DF techniques (for instant come-as-you-are use) because everyone can give data, not just the 1% with DF equipment. *And*, EVERYONE with a radio even if they hear NO SIGNAL is contributing VALUABLE info that can be used to rapidly build the big-picture and localize a signal source. Unfortunately, most of the follow-on clones of APRS did not implement the two original APRSdos OMNI DF techniques which were fundamental to APRS from the beginning. Thus, very few people these days know they exist or use them much... But anyone can still enter a DF report no matter what software they use. See how to Enter a DFS report using UI-view..."