In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable (or aliases of one another) when sampled. It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal.
Keeping this in view, what is Nyquist limit in ultrasound?
The PRF limit within which aliasing occurs is known as the aliasing or the Nyquist limit. Specifically, aliasing occurs when the velocity is more than one half of the pulse repetition frequency. To a certain degree the PRF can be increased to permit higher velocities to be displayed.
What does PRF means in ultrasound?
Pulse repetition frequency (PRF) The PRF is the number of pulses (send and listen cycles) of ultrasound sent out by the transducer per second. It is dependent on the velocity of sound and on the depth of tissue being interrogated.
How can we avoid aliasing?
The Nyquist Sampling Rate is the lowest sampling rate that can be used without having aliasing. The sampling rate for an analog signal must be at least two times the bandwidth of the signal. So, for example, an audio signal with a bandwidth of 20 kHz must be sampled at least at 40 kHz to avoid aliasing.