i am programming for google android and i wonder if the scans for wireless 802.11 networks are done passively or actively? i mean: does the device actually emit a beacon request signal on WifiManager.startScan()
or does it just listen for beacons sent periodically by the access points?
Android does passive scans, it listens for beacons. Doing an active scan can create a lot of congestion on the network by sending out probe requests and waiting for probe responses.