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(EST)-ELECTRONIC SYSTEMS AND TECHNOLOGIES > SIGNAL AND NOISE > Flashcards

SIGNAL AND NOISE Flashcards

1
Q

any unwated form of evnergy that inteferes with transmitted signals

A

NOISE

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2
Q

deviation of received signal from its expected form cause by the imperfect response of a system

A

DISTORTION

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3
Q

contamination caused by interaction with other signals from other sources.

A

INTERFERENCE

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4
Q

two types of interference

A

constructive and destructive interference

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5
Q

a noise that is only present when the signal is also present

A

CORRELATED NOISE

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6
Q

2 main catergories of noIse

A

CORRELATED NOISE

UNCORRELATED NOISE

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7
Q

UNWANTED MULTIPLES OF A SINGLE FREQUENCY CREATED WHEN AMPLIFIED IN A NON LINEAR DEVICE

A

HARMONIC DISTORTION

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8
Q

UNWANTED CROSS-PRODUCT FREQUENCY CREATED WHEN SIGNALS ARE MIXED IN A NON LINEAR DEVICE

A

INTERMODULATION DEVICE

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9
Q

TYPE OF NOISE WHERE IT IS PRESENT REGARDLESS OF SIGNAL

A

UNCORRELATED NOISE

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10
Q

2 TYPES OF UNCORRELATED NOISE

A

EXTERNAL AND INTERNAL NOISE

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11
Q

2 KINDS OF EXTERNAL NOISE

A

EXTRATERRESTRIAL NOISE

TERRESTRIAL NOISE

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12
Q

2 EXAMPLES OF EXTRATERRESTRIAL NOISE

A 
SOLAR NOISE (SOLAR FLARES/ SUN SPOT CYCLE/ RADIATION)
& 
COSMIC NOISE ( NOISE FROM OTHER CELESTIAL BODIES)
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13
Q

2 EXAMPLES OF TERRESTRIAL NOISE

A

ATMOSPHERIC NOISE (LIGHTNING DISCHARGES AND OTHER ELECTRIC DISTURBANCES. LESS SEVERE ABOVE 30MHZ

INDUSTRIAL NOISE (A.K.A MAN MADE NOISE)

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14
Q

TYPES OF INTERNAL NOISE

A

THERMAL NOISE (RAPID AND RANDOM MOVEMENTS OF ELECTRONS)

SEMICONDUCTOR NOISE

MISCELLANEOUS NOISE

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15
Q

FOUR OTHER TERMS FORM THERMAL NOISE

A

WHITE NOSE
BROWNIAN NOISE
JOHNSON NOISE
GAUSSIAN NOISE

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16
Q

WHAT IS THE MAIN CONTRIBUTOR TO INTERNAL NOISE

A

RESISTORS

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17
Q

formulas for NOISE POWER & VOLTAGE NOISE FOR RESISTORS

A

Pn=kTB , Vn=√4kTRB

botzmann constant= k = 1.38x10^-23 (m^2 Kg s^-2 K^-1)
ambient temp= T = 290K
Bandwidth = B = (hertz) hz
Resistance= R = (ohms)

18
Q

2 ELECTRONIC DEVICES/PARTS THAT CONTRIBUTE TO THERMAL NOISE

A

RESISTORS &

RC NETWORKS

19
Q

RC NETORKS NOISE FORMULAE

-capacitor and inductor doesn’t generate noise, they only shape noise as they are frequency dependent devices

A

VOLTAGE NOISE= Vn = √(kT/C)

BANDWIDTH= B = 1/(4RC)

Capacitance= C

20
Q

3 TYPES OF SEMICONDUCTOR NOISES (internal)

A

SHOT NOISE

BURST NOISE

avalance noise

21
Q

KIND OF NOISE THAT IS DEPENDENT ON THE CURRENT FLOW INSTEAD OF THE TEMPERATURE
(also give the formula )

A

SHOT NOISE= i(n)= √[2Bi(dc)q]
B= hz
i(dc)= direct current (A)
q= charge of an electron 1.609x10^-19 Coulombs (C)

22
Q

IS A LOW FREQUENCY NOISE WHICH APPEARS AS A SERIES OF BURST OF TWO OR MORE LEVELS. (CAN BE OBSERVED IN BJT’S)

A

BURST NOISE

23
Q

this noise is created when avalance breakdown occurs, it can be used for noise generators

A

avalance noise

24
Q

kinds of miscellaneous noises

A

transit time noise

flicker noise

25
Q

this noise is similar to shot noise but occurs when the transit time for electrons is comaparable to the signal’s period.

A

transit time noise

26
Q

this noise if proportional to emiter current and junction temperature, inversely proportional to frequency (negligible above 500Hz)

A

flickers noisez

27
Q

flicker noise is also called as?

A

1/f noise
pink noise

since it it inversely proportional to the frequency.

28
Q

measure of signal’s power content vs ffrequency

A

POWER SPECTRAL DENSITY

29
Q

POWER SPECTRAL DENSITY (Sp)

pormyula

A

Sp = kT

Sp (unit= w/hz , v^2/hz, A^2/hz)

(boltmann contant =k)
= 1.38x10^-23 m^2 Kg s^-2 K^-1

(T= ambient temp)= 290K

30
Q

noise voltage across a resistor.

A

Pn = kTB
Vn^2/R = kTB
(Vn/2)^2 / R = kTB

31
Q

total noise voltage (series)

A 
Vn = √(4kTRB) ----
Vn(total) =  √(4kT(R1+R2 )B)----
32
Q

total noise current (parallel)

A 
G=1/R  = conductance
In(total) =  √(4kT(G1+G2 )B)
33
Q

(equivalent noise ratio)

of cascading devices

A

Req =(equialent noise ratio)= R1 + R2/G1 + R3/G1G2 + ….

34
Q

RELATIVE MEASURE OF THE DESIRED SIGNAL POWER TO THE UNDESIRED POWER

A

(SNR)
SIGNAL TO NOISE RATIO
SNR = Ps / Pn = Vs^2/ Vn^2

SNR(db) = 20 log Vs/Vn = 10log Ps/Pn

    • higher SNR the better
    • usually by decibels
35
Q

MINIMUM SNR NOISE FOR: (in db)

TELEPHONE SERVICE:
TRANSMISSION (VIDEO)=
TRANSMISSION (DATA)=

A

TELEPHONE SERVICE: 30db
TRANSMISSION (VIDEO)= 45db
TRANSMISSION (DATA)= 15db

36
Q

specufues how noisy a device is….

A 
NOISE FACTOR (NF)
NF= SNR(in)/ SNR(out) =
37
Q

ideal NOISE FACTOR = ?

A

NF= SNRi/ SNRo = (Si/Ni)/(GSi/GNi) =1

1

38
Q

a device with noise

A

NF= SNRi/ SNRo = (Si/Ni)/(GSi/GNi + Na)

then resulting NF is > 1 (not ideal)

39
Q

NOISE FACTOR, how to express in db?

A

NF(db) = 10log [(Si/Ni / So/No]

40
Q

total noise factor of cascading amplifiers

A

NFeq = NF1 + (NF2 -1)/G1 + (NF3-1)/G1G2

(EST)-ELECTRONIC SYSTEMS AND TECHNOLOGIES (2 decks)

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