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EE30175 Digital Audio Signsl Processing > Basics > Flashcards

Basics Flashcards

1
Q

What are the broad classifications of signals?

A

Continuous time, discrete time, continuous value, discrete value, random, nonrandom

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2
Q

What is a continuous-time signal?

A

A signal defined at every instant of time over some time interval

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3
Q

Another common name for a continuous-time signal is _______.

A

analog signal

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4
Q

What is Forrier Transform in simple terms

A

The Fourier transform is an analysis process, decomposing a complex-valued time function into its constituent frequencies and their amplitudes.

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5
Q

What is the process of sampling a signal?

A

sampling refers to the process of reducing a continuous-time (CT) signal to a discrete-time (DT) signal, which is defined only on a discrete subset of the time axis.

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6
Q

What is a discrete-time signal?

A

A signal with defined values only at discrete points in time

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7
Q

How can a discrete-time signal be created?

A

By sampling a continuous-time signal or from an inherently discrete-time system

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8
Q

What is a continuous-value signal?

A

A signal that may have a value anywhere within a continuum of allowed values

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9
Q

What is a continuum?

A

A set of values with no space between allowed values

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10
Q

What is an example of a continuum with infinite extent?

A

The set of real numbers

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11
Q

What is a discrete-value signal?

A

A signal that can only have values from a discrete set of values

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12
Q

What characterizes a discrete set of values?

A

There is a finite space between allowed values

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13
Q

Give an example of a discrete set of values.

A

The set of integers

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14
Q

What is a digital signal?

A

The transmission of a sequence of values of a discrete-time signal in encoded form

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15
Q

What is a random signal?

A

A signal whose values cannot be predicted exactly and cannot be described by any mathematical function

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16
Q

What is a nonrandom signal also known as?

A

Deterministic signal

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17
Q

What is another common name for a random signal?

A

Noise

18
Q

What is a transmitter? A receiver? And a channel?

A

A transmitter is a device that produces a signal.

A receiver is a device which acquires the signal.

A channel is the path a signal and/or noise stick from a transmitter and/or noise source to. receiver.

19
Q

What is a continuous time signal?

A

A continuous time signal is one which is defined at every instant of time over sometime interval another common name for a continuous time signal is then analog signal.

20
Q

What is sampling?

A

The process of sampling is a signal is to take values from it as discreet points in time and then to use only the samples to represent the original continuous time signal the set of examples ticket from continuous time signal is one example of this great time signal

21
Q

What is a digital signal?

A

A digital signal is the transmission of a sequence of values of a discreet time signal in the form of digits and some encoded form usually binary the term digital is also sometimes used loosely to refer to a discrete value signal which only has two possible values

22
Q

What is a random signal?

A

A random signal is one whose values cannot be predicted exactly and cannot be described by any mathematical function

23
Q

What is a deterministic signal?

A

A deterministic signal is one which can be mathematically described at least approximately

24
Q

What is sampling in signals?

A

The process of sampling acquires its values of discrete times and that sequence of values constitutes a continuous value, discreet time signal

25
Q

What is quantisation?

A

The process of quantisation approximate each sample as the newest member of a finite set of discreet value values producing a discrete value, discrete signal

26
Q

What happens when continuous time signals that can be described by mathematical functions are transformed through continuous time Fourier transform CTFT?

A

They are transformed into another domain called the frequency domain

27
Q

What is time invariant?

A

A time shifting input only results in equal time shift in output.

If x(t) -> y(t)
x(t-T) -> y(t-T)

28
Q

What’s linearity

A

Proportionate; if input is scaled, output is scaled.

If x(t) -> y(t)
ax(t) -> ay(t)

29
Q

What is Forrier transform?

A

It is a mathematical tool used to analyse signals by transforming them from the time domain to the frequency domain

30
Q

what is

X(f)=∫x(t).e^{-j 3 pi f t} dt

A

Continuous signal Fourier transform

X(f): frequency-domain representation of x(t)
f: continuous frequency variable
e^… : complex exponential that represents sinusoidal components.

31
Q

What is

X(e^jw)=∑x[n].e^{jwn}

A

X(…): frequency representation of x[n]
w: angular frequency, normalised to 0,2pi

32
Q

What’s power spectral density

A

P(f) of a signal indicates the power per unit frequency at each frequency f. Particularly useful for random or non-periodic signals.

33
Q

What is a spectrogram?

A

A spectrogram is a visual presentation of the frequency content of a signal as it changes overtime it’s combines both time domain and frequency domain information providing insights into how the signal spectral composition evolves 

34
Q

Homogeneous responses

A

y(ax)=ay(x)

35
Q

Superposition or additive response

A

y(x+z)=y(x)+y(z)

36
Q

What’s Taylor expansion

A

Used to make a non-linear equation approximately linear around a point.

f ( x ) = f ( a ) + f ′ ( a ) ( x − a ) + f ″ ( a ) 2 ! ( x − a ) 2 + f ‴ ( a ) 3 !

The more terms the smaller and less significant

37
Q

An LTI system can be decomposed into cascade building blocks, what are the blocks?

A

Modulator

Transmitter

Propagation

Antenna

Demodulator

38
Q

What is Dirac delta function

A

The Dirac delta function, often denoted as 𝛿(𝑡), is a mathematical construct used in signal processing to model an idealized impulse. It is not a function in the traditional sense but a generalized function or distribution.

39
Q

What does a delay in impulse results in?

A

Time will they results in more jumps or rotations in the delayed impulse due to more complex phase

40
Q

What does a delay in impulse results in?

A

Time will they results in more jumps or rotations in the delayed impulse due to more complex phase

EE30175 Digital Audio Signsl Processing (1 decks)

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