Lec 6: Design Considerations Flashcards Preview

EE20083 Signal processing > Lec 6: Design Considerations > Flashcards

Flashcards in Lec 6: Design Considerations Deck (28)
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1
Q

The phase and magnitude of a frequency response?

A
2
Q

Filter phase linearity key information?

A

In this example, the phase response is said to be linear, because it is a linear function of frequency.

Not all filters have linear phase.

3
Q

Checking that the filter response is linear?

A
4
Q

Consider breaking down a square wave into individual frequency components, each component is then scaled and shifted (by the filter magnitude and phase response) and then summed back together.

Linear Phase

A
5
Q

Consider breaking down a square wave into individual frequency components, each component is then scaled and shifted (by the filter magnitude and phase response) and then summed back together.

Non-linear phase?

A
6
Q

Identifying linearity in a signal with a greater number of cisoid terms?

A

Black - Linear phase means that all frequencies are delayed equally, and so the waveform morphology is minimally distorted.

Red - Non-linear phase means that some frequencies are delayed more than others, leading to greater distortion of the signal morphology.

7
Q

The four types of Linear Phase FIR filters

A
8
Q

The symmetry and anti-symmetry of an impulse response?

A
9
Q

The impulse response of type 1 Linear phase FIR filter?

A
10
Q

The impulse response of type 2 Linear phase FIR filter?

A
11
Q

The impulse response of type 3 Linear phase FIR filter?

A
12
Q

The impulse response of type 4 Linear phase FIR filter?

A
13
Q

The all pass filter?

A
14
Q

All pass filter example

A
15
Q

What is Zero phase filtering?

A

Sometimes we want to ensure that we have no effect on the phase at all (i.e we do not want any shift in any frequency component).

This is called zero phase filtering and is actually quite easy to do, but only offline once a signal has already been captured.

16
Q

How is zero phase filtering conducted?

A
17
Q

Where is zero phase filtering used?

A

Zero phase filtering can be very important in applications where the timing information needs to be preserved (for example in a communications system, or in the analysis of biomedical signals).

18
Q

casual/non-casual zero phase filtering?

A

non-casual

19
Q

zero phase filtering MATLAB

A
20
Q

Differences in FIR IIR stability?

A

FIR filters (realised non-recursively) are unconditionally stable (all poles are at 0).

21
Q

FIR IIR linearity differences?

A

FIR filters can have an exactly linear phase response, this is an important requirement in many applications such as digital audio processing.

22
Q

The effect of finite precision in FIR and IIR?

A
23
Q

FIR IIR differences number of coefficients?

A

FIR filters require more coefficients (higher order) for sharp cutoff characteristics than IIR filter. Thus equivalent FIR filters tend to be much larger and slower than IIR filters.

24
Q

FIR and IIR differneces Analogue filters ?

A

Analogue filters may be readily transformed into equivalent IIR digital filters (due to the feedback terms). This is not possible with FIR digital filters as they have no analogue counterpart.

25
Q

FIR and IIR differences ease of design?

A

In general, FIR filters are more difficult to design, unless CAD support is available.

26
Q

When to use IIR filtering?

A

Use IIR when the only important requirements are sharp cutoff and high throughput (low order).

27
Q

When to use FIR filtering?

A
28
Q
A