What is the difference between active scan and passive scan?

Question

What is the difference between mWifiManager.startScanActive() and mWifiManager.startScan().
What is the difference between active scan and passive scan?

Unconscious

@user I hope you don't mind that I changed the title, because that was really the question – Hugely

Answer 1

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.

Hugely

Thank you very much! I have got it: startScanActive is a active scan, and startScan is a passive scan. – Unconscious

Answer 2

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...

Acariasis

Answer 3

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.

Gwenny