Frequency Domain Analysis Flashcards

1
Q

Which part of a discrete fourier series is real?

A

Even - Cosine part

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2
Q

Which part of a discrete fourier sries is Imaginary?

A

Odd - Sine

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3
Q

Describe what the spectra of a periodic series is….

A

It is where a fourier series calculation is performed on a signal. There is a formula that is used to represent the calculaiton. The table method can be used to seperate the real and imaginary part to calulate the solution. The answer is represented by ak and ai and can be split into ints magnitude and its phase

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4
Q

What is the symbol representation of the imaginary and real part of a fourier series

A

ak = real ai = imaginary

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5
Q

Name the mthod of solving a fourier series and briefly describe it

A

Tablular method. This is where you take each calculation of each element in the series (k substittions) and seperate it into its imaginary and real parts.

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6
Q

What effect does using a unit step function have on a fourier series calculation

A

it means that the sum is used to calculate the series rather than just an impulse each element it caluclated individually.

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7
Q

which conditions are a fourier series used as a calculation

A

frequency analysis on the point where the data is represented as a periodic series (i.e cosine, sines etc… repeating itself etc…)

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8
Q

Describe the magnitude of a fourier series

A

the square root of the (real part squared + the imaginary part squared)

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9
Q

describe the phase of the fourier series

A

arctan of the real part divided by the imaginary part

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10
Q

NAme the 6 properties of a fourier series

A

Linearity time shifting differentiation integration circular convolution modulation

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11
Q

describe what linearity is

A

The sum of two weights (elements) is equal to the addition of each of the respective weights (elements)

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12
Q

time shifting is..

A

defines the effect of shifting x[n] by n0 at sampling intevals. it changes the phase (moves it along) but not the magnitude

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13
Q

differentiation

A

Used to estimate the slope of sigma

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14
Q

integration

A

running sum of x[n]. only period if x[n] has zero averages

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15
Q

circular convolution

A

over one period it ensures the convergence of the summation It also shows that time domain convolution is equal to the frequency domain multiplication

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16
Q

modulation

A

over one period

17
Q

What is a fourier transform?

A

It is a way manipulated data in the frequency domain. This is because the frequency and time domain can be mapped to each other and convolution or multiplication can be performed on both of them.

18
Q

Foruier trasnsform may be suitable for what?

A

aperiod signals with properties and pairs

19
Q

Describe how a fourier transform looks different to a descrete signal

A

it is continous and in terms of X(omega) instead of x[n]. it is also a very different shape as some DSP operation has been performed on it by an LTI processor.

20
Q

Formula for a spectra of periodic series in a fourier series

A
21
Q

Describe a table where the tabular method has been used to solve a fourier series

A
22
Q

Formula for calculating the phase and magnitude of a FS

A
23
Q

Derive FT part 1:

A
24
Q

FT derive part 2:

A
25
Q

FT derive part 3:

A
26
Q

FT derive par t4:

A
27
Q

What are the properties of fourier transform?

A

Linearity

Time shifting

Convolution

28
Q

Draw the mathematical descriptions of the properties of the fourier transform…

A
29
Q

how does the fourier transform with the frequency domain map to the time domain?

A
30
Q

What are the equations that map from frequency domain to time domain within the foruier tranform.

A
31
Q

How do you calulcate the frequency response H(omega) - graphic formula

A
32
Q

discrete to fourier graph…

A
33
Q

What times of signal are the foruier transform and fourier series used for repectively

A

fourier transform - aperiodic

fourier series. - periodic

34
Q

Fourier series table…

operation | periodic signal | discrete fourier series | - 9 rows

A
35
Q

The fourier transform of aperiodic signals : properties and pairs:

properties: operation | signal | FT | - 7 rows

pairs - | waveform | signal | spectrum X(omega) | - 5 rows

A
36
Q
A