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.

Apodization is a method for reducing side lobes (lateral array elements) in some arrays. It gradually decreases the vibration of the transducer surface with distance from its center by improving the directivity. It is usually accomplished by using more power to excite the innermost elements.

Frame averaging is a form of lowpass filtering. With frame averaging temporal variation are smoothed by addition of consecutive frames in a real-time mode.

The motion discrimination detector is used for signal processing in color Doppler systems to distinguish between Doppler shifts from moving blood and moving tissue.

See also Zero Crossing Detector.

The multiple frame trigger adjusts the acquisition of a series of consecutive frames, usually with ECG triggering. Multiple frame triggers are used in harmonic power Doppler modes to identify motion artifacts in contrast enhanced Doppler imaging.

The wall filter is designed to exclude Doppler signals with low frequency, and high amplitude (highpass filter) from moving tissue, such as a vessel wall. Wall filter performance is critical for effectiveness of a color Doppler system.