(DAC) Part of the interface that converts digital numbers from the computer into analog (ordinary) voltages or currents. In ultrasound systems e.g., the high voltage transmit amplifiers that drive the transducers might be controlled by digital to analog converters (DACs) to shape the transmit pulses for better energy delivery to the transducer elements.

The Doppler velocity signal refers to a signal whose voltage is proportional to the Doppler frequency shift, obtained by a frequency-to-voltage conversion of the Doppler signal.

See also Autocorrelation, Temporal Mean Velocity, Doppler Effect, Doppler Ultrasound and Maximum Venous Outflow.

Amplitude shading is a method of reducing the side lobe levels in a transducer array. The shading usually causes the main beam to broaden by applying different voltages to the elements of the array.

See also Analog Output Signal.

The analog output signal is voltage output corresponding to the parameter measured by a device. The produced signal is calibrated by a scaling factor.

Digital systems use discrete numerical values or non-numeric symbols for input, processing, transmission, storage, or display rather than being composed of variable voltage, acoustic field or electromagnetic field.

See also Digital Imaging and Communications in Medicine and Analog to Digital Converter.