B1P2 - An introduction to the theory of signals

Question 1

amplitude-shift keying (ASK)

Answer 1

where symbols are repped by segments of a carrier signal with different amplitudes;

Question 2

angular frequency (omega)

Answer 2

omega = 2pif = (2*pi) / T = rad s^-1;

Question 3

baud (Bd)

Answer 3

number of symbols transmitted per second;

Question 4

bit error rate (BER)

Answer 4

the number of bits received in error as a proportion of the number of bits transmitted;

a BER <= 10^-7 is considered acceptable;

Question 5

carrier wave

Answer 5

a signal in a channel modulated by another signal containing the message data;

Question 6

Fourier series

Answer 6

a periodic signal repped as the summation of sinusoids;

Question 7

Fourier tranform

Answer 7

for an aperiodic signal: FourierTransform(timeDomain_rep) = frequencyDomain_rep;

Question 8

frequency domain (rep)

Answer 8

repping a signal in terms of its component frequencies;

Question 9

frequency-shift keying (FSK)

Answer 9

where symbols are repped by segments of a carrier signal with different frequencies;

Question 10

fundamental frequency

Answer 10

the lowest frequency component of a signal;

Question 11

harmonic

Answer 11

a natural-number multiple of the fundamental frequency of a periodic waveform;

Question 12

I wave

Answer 12

the in-phase component of a quadrature[(2*pi)/4]-modulated signal;

Question 13

main lobe

Answer 13

the interval of a continuous spectrum containing most of the signal energy;

Question 14

aperiodic signal

Answer 14

a non-repeating signal;

Question 15

orthogonal

Answer 15

a relation between two signals, where they can be sent simultaneously and each completely recovered at the receiver;

Question 16

phase-shift keying (PSK)

Answer 16

where symbols are repped by segments of a carrier signal with different phases [e.g. differring in phase by pi];

Question 17

quadrature

Answer 17

the relation between sine (I) and cosine (Q) waves, whose phase differs by (2*pi)/4; quad relation never changes even if one or both waves are multiplied by -1;

can therefore rep 4 symbols, each consisting of two bits: 00 = +sin+cos; 01 = +sin-cos; 10 = -sin+cos; 11 = -sin-cos;

Question 18

quadrature amplitude modulation (QAM)

Answer 18

where symbols are repped using the quad scheme (2 bits) AND the I and Q waves also taking different amplitudes;

Question 19

quadrature phase-shift keying (QPSK)

Answer 19

where symbols are repped using the quad scheme (2 bits) AND the I and Q waves each taking on different phases (while also preserving their quad-relation);

Question 20

Q wave

Answer 20

the cosine wave of a quad-modulated signal;

Question 21

side lobes

Answer 21

the lower-energy tail ends of a signal’s main lobe in a continuous spectrum;

Question 22

signal constellation diagram

Answer 22

a graph whose axes rep the signs (+/-1) and amplitudes of the I and Q waves, and whose points rep the symbols of the signal;

Question 23

spectrul nulls

Answer 23

intervals where the spectral energy is zero on a continuous spectrum;

Question 24

symbol

Answer 24

an element from a finite source alphabet;

Question 25

time domain

Answer 25

repping the amplitude of a signal as a function of time;