Basics

Question 1

What are the broad classifications of signals?

Answer 1

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

Question 2

What is a continuous-time signal?

Answer 2

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

Question 3

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

Answer 3

analog signal

Question 4

What is Forrier Transform in simple terms

Answer 4

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

Question 5

What is the process of sampling a signal?

Answer 5

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.

Question 6

What is a discrete-time signal?

Answer 6

A signal with defined values only at discrete points in time

Question 7

How can a discrete-time signal be created?

Answer 7

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

Question 8

What is a continuous-value signal?

Answer 8

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

Question 9

What is a continuum?

Answer 9

A set of values with no space between allowed values

Question 10

What is an example of a continuum with infinite extent?

Answer 10

The set of real numbers

Question 11

What is a discrete-value signal?

Answer 11

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

Question 12

What characterizes a discrete set of values?

Answer 12

There is a finite space between allowed values

Question 13

Give an example of a discrete set of values.

Answer 13

The set of integers

Question 14

What is a digital signal?

Answer 14

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

Question 15

What is a random signal?

Answer 15

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

Question 16

What is a nonrandom signal also known as?

Answer 16

Deterministic signal

Question 17

What is another common name for a random signal?

Answer 17

Noise

Question 18

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

Answer 18

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.

Question 19

What is a continuous time signal?

Answer 19

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.

Question 20

What is sampling?

Answer 20

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

Question 21

What is a digital signal?

Answer 21

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

Question 22

What is a random signal?

Answer 22

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

Question 23

What is a deterministic signal?

Answer 23

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

Question 24

What is sampling in signals?

Answer 24

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

Question 25

What is quantisation?

Answer 25

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

Question 26

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

Answer 26

They are transformed into another domain called the frequency domain

Question 27

What is time invariant?

Answer 27

A time shifting input only results in equal time shift in output. If x(t) -> y(t) x(t-T) -> y(t-T)

Question 28

What’s linearity

Answer 28

Proportionate; if input is scaled, output is scaled. If x(t) -> y(t) ax(t) -> ay(t)

Question 29

What is Forrier transform?

Answer 29

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

Question 30

what is X(f)=∫x(t).e^{-j 3 pi f t} dt

Answer 30

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

Question 31

What is X(e^jw)=∑x[n].e^{jwn}

Answer 31

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

Question 32

What’s power spectral density

Answer 32

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

Question 33

What is a spectrogram?

Answer 33

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 

Question 34

Homogeneous responses

Answer 34

y(ax)=ay(x)

Question 35

Superposition or additive response

Answer 35

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

Question 36

What’s Taylor expansion

Answer 36

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

Question 37

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

Answer 37

Modulator Transmitter Propagation Antenna Demodulator

Question 38

What is Dirac delta function

Answer 38

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.

Question 39

What does a delay in impulse results in?

Answer 39

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

Question 40

What does a delay in impulse results in?

Answer 40

system’s response to shift in time without altering its shape or magnitude. Here’s how it affects the system in the time domain and frequency domain

Question 41

What is Nyquist Theorem

Answer 41

Sampling rate f_s must be at least twice the signal’s highest frequency f_max to avoid aliasing

Question 42

What is aliasing

Answer 42

Overlapping of frequency components resulting from a sample rate below the Nyquist rate

Question 43

Equation for CT sinusoid

Answer 43

g(t) = A cos(2*pi*f_0 + theta) = A cos(w_0*t + theta)