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TELECOM MIDTERM > Study Sheet > Flashcards

Study Sheet Flashcards

1
Q

What is sound?

A

Audible frequencies created by a source such as a person talking.

A periodic variation in air pressure.

travels in form of sound waves

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2
Q

types of sound waves

A

Pressure waves that vibrate molecules in a medium such as the air.

high frequency vs low frequency

loud vs soft (amplitude)

pleasant vs noise

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3
Q

frequency

A

number of cycles per second

Number of events happening over a defined time period.

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4
Q

wavelength

A

length of the waveform

The length of one complete waveform. The higher the frequency, the shorter the wavelength; and the lower the frequency, the longer the wavelength.

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5
Q

what is a decibel used for

A

unit used to measure signal strength

used on a logarithmic scale

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6
Q

convert decibels to milliwatts

10 milliwatts equals how many decibels

100 milliwatts equals how many decibels

A

10mw = 10dbm

100mw = 20 dbm

milli watts on the x axis and decibels on the y

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7
Q

to double a milliwat is how many decibels

A

3

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8
Q

human ear can hear from qhat decibel to what decibel

A

0-120

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9
Q

formula to convert power to decibels

A

Decibels (dB) = 10 log(P2/P1)

P1 is reference and P2 is output

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10
Q

frequency of human hearing

A

20 Hz

20,000Hz
20kHz

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11
Q

frequency of human speech

A

400 hz

4,000 hz

4khz

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12
Q

local loop

A

subscriber loop consisting of twisted pair connecting each phone to local exchange.

has both DC and AC power

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13
Q

ADSL

A

Asynchrnous Digital Subscriber Line

used for internet access on same wires

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14
Q

local exchange office does what

A

provides power to telephone circuits

dial tone

ring signal

other info and billing tracking

circuitry for routing

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15
Q

ringing voltage

A

90 VAC at 20 hz

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16
Q

where do telephones enter home business

A

demarcation point

subscriber interface

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17
Q

LEC

A

local exchange carrier

local companies that provide phone service

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18
Q

LATA

A

local area and transport network

geographic regions

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19
Q

POP

A

point of presence office for that compnay in a LATA

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20
Q

trunks for long distance carriers are called

A

IXC;s

inter exchange carrier

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21
Q

IXC

A

interexchange carrier

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22
Q

what is DTMF

A

Dual Tone Multi Frequencey

used for dialing and sending the number input as a frequency to the central office

23
Q

Steps of Analog to Digital conversion

A

Sampling-8000 times

Quanitizing: compares to 255 level scale

Encoding: Translating PAM sample into PCM word converted into bipolar signal and multiplexed into DS-1

24
Q

digital modulation techniques

A 
ASK-amplitude
FSK-frequencey
PSK-phase shift
QAM-quadrature amplitude
PCM-pulse code modulation
25
Q

PCM

A

pulse code modulation is used for converting in todays modems

26
Q

B8ZS

A

binary 8 zero binary 8 substitute

8 zeros are converted to a special bit pattern that is a bipolar violation due to FCC rules

27
Q

AMI

A

alternate mark inversion not widely used replaced by B8Zs

28
Q

FDM

A

Frequncey Division Multiplexing

puts different frequenceys on one signal

29
Q

TDM

A

time division multiplexing

puts digital words into time slots in one signal

30
Q

another name for channel

A

DS-0

31
Q

how many DS-0 in DS-1

A

24

32
Q

How may DS-1 in a DS-3

A

28

33
Q

How many DC-3 in OC 48

A

48..what ever the number is thats how many DC-3’s

34
Q

whats the name of the multiplexer turning DS-1 into DS-3

A

M13 Multiplexer

35
Q

channel banks

A

convert DS0 into DS1

36
Q

DS3 bandwidth

A

45 MBps

37
Q

DS-0 bandwidth

A

64kp

38
Q

DS-3 cable is

A

coax or fiber

39
Q

DS-3 can also be sent overe

A

microwave…3 per channel

40
Q

DS-3 framing formats

A

M13

C bit parity

Unchannelized

41
Q

SONET is

A

synchrnous opitcal network

Sonet frames are similar to TDM protocols

relies on external clock and not timing bits

42
Q

4 types of fast packet multiplexing

A

Statistcal fast packet

Asynchrnous Transfer Mode ATM-multiplexes fixed length cells

Frame Relay-multiplexes variable length packets

IP…multiplexes variable length packets

43
Q

DWDM

A

dense wave divsion multiplexing is multiplexing for fiber optic systems

44
Q

4 types of transmissino modes

A

serial-one bit after other
parrallel-bits across multiple conductos

asycnhrnous-start and stop bits to define frames

synchrnous-clock source to synch frames

45
Q

SS7

A

signaling system 7….

out of band signaling used to SETUP calls

46
Q

Trunk

A

circuit shared by multiple users that CONNECTS SWITCHES

47
Q

Tandem switch

A

switch connected to other switches

48
Q

CLEC vs ILEC

A

competetive local exchange carrier

Incumbent local exchange carrier

49
Q

feature group trunk

A

trunk used to connect LONG DISTANCE to LOCAL switches

50
Q

IMT

A

inter-machine trunks

51
Q

what kind of switch switches international calls

A

gateway switch

52
Q

most common network

A

T1 or DS1 same thing

53
Q

LEvels of switches

A

Class 5-local
Class 4-Tandem
Class3-LD switch

international gateway switch

TELECOM MIDTERM (12 decks)

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