An automated external defibrillator ("AED") (10) employing a self-test circuit (11) and an encoded status indicator. The self-test circuit (11) automatically tests AED (10) and dependent upon the tests, generates both a base status signal (110) indicative of an operational readiness of AED (10) and a test status signal (120) indicative of self-test information of AED (10). The encoded status indicator concurrently visually indicates both the base status signal (110) and the test status signal (120) with the visual indication of the base status signal (110) being perceivable to a human eye and the visual indication of the test status signal (120) being unperceivable to the human eye. The encoded status indicator may employ a light source (14) for emitting a status light (20) and an encoder (13) to intensity modulate the status light (20) as emitted by the light source (14) as a function of an encoding of the base status signal (110) and the test status signal (120) by the encoder (13).
