The process of using a radio scanner with a automatic transmitter frequency identification feature (near field reciever) and following the action live without having to know the frequencies in advance. Related to WarDriving WarWalking and WarChalking as it is associated with finding open internet access points. Optoelectronics calls the feature a "Sweeper". Uniden calls it "Close Call" and Radio Shack calls it "Signal Stalker".
When I got to the scene I was not sure which agencies were in charge and transmitting so I went into "WarScanning" mode to hear the activity.