What is the difference between mWifiManager.startScanActive() and mWifiManager.startScan().
What is the difference between active scan and passive scan?
Passive scanning listens to beacons sent by the access points. That means waiting for the beacon to be sent (usually a few seconds).
An active scanning will emit probes to those APs immediately.
please note that an active scan will consume more energy and as "ordinary" wifi access points broadcast their beacons several times per second, an active scan is rarely needed. e.g. requesting a list of wifi networks in reach takes approx 0.7 seconds to finish. so this should be sufficient...
02/19/2013 jadiyappa :
Active scanning is required when enabled the "SSID Hide" in AP. Passive scanning is always waits for the beacon frames from AP.
来源：https://stackoverflow.com/questions/5958715/what-is-the-difference-between-active-scan-and-passive-scan