BeginnerTopic 22 of 101Signals, Control & Comms
Filtering concept
Systems that modify frequency content.
In depth
Filtering selectively modifies frequency content: pass, attenuate or phase-shift components. Ideal filters have brick-wall responses (non-causal); practical filters approximate them with transition bands and ripple. Applications: noise removal, band selection, anti-aliasing, equalisation.
Key points
- Passband, stopband, transition band
- Cut-off frequency
- Group delay
ExampleA low-pass filter at 3.4 kHz limits telephone speech bandwidth.
Filters change the frequency content of a signal, which is how noise is removed, bands are selected and signals are shaped.
What is Filtering concept?
Systems that modify frequency content.
Why is it important to understand filtering concept?
Filters change the frequency content of a signal, which is how noise is removed, bands are selected and signals are shaped.
What is a low-pass filter?
A filter that passes low frequencies and attenuates high frequencies, which is used to remove noise and prevent aliasing.
What is a filter's cutoff frequency?
The frequency at which the output power falls to half of the passband value, which is about 70.7 percent in amplitude.
How is Filtering concept used in practice?
Typical applications include removing mains hum from an instrument signal, selecting a radio station from a band of signals and shaping the response of an audio equaliser.
What should I learn before Filtering concept?
Study "Signal flow graphs and Mason's rule" first (topic 21 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Filtering concept?
Passband, stopband, transition band. Cut-off frequency. Group delay.
Can you give an example of Filtering concept?
A low-pass filter at 3.4 kHz limits telephone speech bandwidth.
What comes after Filtering concept?
The next topic is "Sampling", which builds directly on this one.
How difficult is Filtering concept?
It is classed as Beginner in Signals, Control & Comms (topic 22 of 101). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.