What is brick-wall filter?
An idealized electronic filter, one that has full transmission in the pass band, and complete attenuation in the stop band, with abrupt transitions, is known colloquially as a “brick-wall filter”, in reference to the shape of the transfer function.
What is a PCM filter?
The filter is the final step of converting PCM digital audio to analogue. It removes the jagged stair step pattern, restoring the waveform to a near perfect representation of the original analogue signal.
What is digital filter in DAC?
In a mixed-signal system (analog and digital), a reconstruction filter, sometimes called an anti-imaging filter, is used to construct a smooth analog signal from a digital input, as in the case of a digital to analog converter (DAC) or other sampled data output device.
What is Wall filter in ultrasound?
The wall filter in ultrasound is a way of filtering out low or high frequency Doppler signals. In clinical ultrasound, it is usually used to filter out very low frequencies that may add noise to a spectral Doppler waveform. A typical use is removing the low frequency reverberation of an arterial wall.
What is a DSD filter?
The DSD format is an unfiltered stream of a 1-bit SD modulator, for high-quality playback of which you need to completely filter out the entire RF noise of the modulator, otherwise it will fold back on the non-linearities of the DACs and analog stage.
Why do DACs Have filters?
A real DAC can’t have infinite bandwidth so it can’t produce perfect impulses or steps, but there are still aliases above the Nyquist frequency which must be filtered.
What happens if wall filter is too low in ultrasound?
A potential pitfall is that the wall filter may filter out genuine low-frequency slow flow, such as venous blood flow. If the goal is to evaluate venous blood flow, make sure the wall filter is set as low as possible.