27AXIS 210A/211A - AudioFull-duplex mode means you can transmit and receive audio (talk and listen) at the sametime, without having to use any of the controls. This is just like having a telephoneconversation. The only controls you may wish to use are the mute buttons to turn off thesound, and the sliders, to adjust the input/output volume levels. This mode requires theclient PC to have a sound card with full-duplex audio support. If your available bandwidthis 0.2 Mbit/s or less, using Half-duplex mode is recommended instead.Half-duplex mode also transmits and receives audio in both directions, but only in onedirection at a time. This means that you must select when to receive or transmit audio withthe help of the push-to-talk button. To speak, press and hold the button (check that themicrophone is not muted). When finished, release the button. You will now receive audiofrom the other end of the connection.When using half-duplex, the Send the sound from the active client to all other clientsoption transmits the audio signal from the client that is talking to all the other clients.Note that the push-to-talk button is configured from AMC; see AXIS Media Control, onpage 24. It is also possible to configure the push-to-talk button so that it toggles betweenthe speaking and listening modes. Half-Duplex mode is best if you only have limitedbandwidth available.When selecting the Simplex - Network Camera speaker only mode, the speaker connectedto the camera plays audio, but no audio is transmitted from the camera to other webclients. This could be used to provide spoken instructions to a person seen in the camera.This mode requires you to use the push-to-talk button.Simplex - Network Camera microphone only mode transmits audio only from the AXIS210A/211A to web clients. It does not receive audio from any other web clients. This canbe used in remote monitoring, and web attractions to provide live audio and video of amonitored situation.Audio InputAudio from an external microphone or a line source can be connected to the Line/Mic injack of the AXIS 210A/211A. The audio source can be set to Internal microphone, Externalmicrophone or Line. If you are using a microphone, the input sensitivity can be set toHigh or Low. See Technical Specifications, on page 57 for the exact maximum levels.The Enable microphone power option provides DC power for an external microphone. Ifusing a small electret condenser microphone such as a clip-on microphone or a PCmicrophone, this option needs to be enabled.To use a high impedance dynamic microphone, DC power should not be enabled. DC powerwill not harm the microphone, but if you are uncertain, try switching it off and on. Thedefault value is DC power enabled. To use a professional microphone requiring 48Vphantom power, you need an external power supply and must use a balanced-unbalancedconverter (audio transformer) in between.