Data Acquisition Toolbox

Running in Full Duplex Mode

The term full duplex refers to a system that can send and receive information simultaneously. For sound cards, full duplex means that the device can acquire input data via an analog input subsystem while outputting data via an analog output subsystem at the same time.

Note that full tells you nothing about the bit resolution or the number of channels used in each direction. Therefore, sound cards can simultaneously receive and send data using 8 or 16 bits while in mono or stereo mode. A common restriction of full duplex mode is that both subsystems must be configured for the same sampling rate.

If you try to run your card in full duplex mode and the following error is returned,

• ?? Error using ==> daqdevice/start
  Device 'Winsound' already in use.
  

then your sound card is not configured properly, it does not support this mode, or you don't have the correct driver installed.

If your card supports full duplex mode, then you might need to enable this feature through the Multimedia Properties dialog box. Refer to Sound Cards for a picture of this dialog box. If you are unsure about the full duplex capabilities of your sound card, refer to its specification sheet or user manual. It is usually very easy to update your hardware drivers to the latest version by visiting the vendor's Web site.

Testing with a CD Player

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