Wire and Wireless Communications (C7 Pastboard: Excel)

ECE Board Exam April 2001

A duration of traffic path occupancy from a call, sometimes referred to as an average duration of occupancy of one or more path from calls.

Holding time

ECE Board Exam November 2000

Frequency band where Total Access Communication System (TACS) is allocated.

935-960 MHz; 890-915 MHz

ECE Board Exam April 2000

Referred as the forward link channel of the cellular duplex system

Cell to mobile unit

ECE Board Exam November 1999

This referred to a condition in a telephone network where the calling party cannot get connected to the party being called

Blocked call

ECE Board Exam April 1999

One of the components of a basic cellular system that handles the billing activities of the network.

Mobile telephone switching office

ECE Board Exam November 1998

Refers to a continuous tone generated in a local exchange terminal through a combination of two frequencies 350 Hz and 440 Hz

Call waiting tone

ECE Board Exam April 1998

A multiple access technique used in GSM cellular system.

TDMA

ECE Board Exam November 1997

What signal-to-noise ratio is required for satisfactory telephone services?

30 dB

ECE Board Exam April 1997

What is the advantage of sidetone?

Assures that the telephone is working

ECE Board Exam November 1996

A special device circuit connecting two private branch exchanges (PBX).

Tie trunk

ECE Board Exam March 1996

The modulation system used for telegraphy is

Frequency shift keying

ECE Board Exam Board April 2001

Describe as the signal-to-noise ratio required to meet a satisfactory telephone service

30 dB

ECE Board Exam November 2000

Which of the following system uses frequency band 870-890 MHz as a transmit band of its base station?

Advanced Mobile Phone Service AMPS

ECE Board Exam April 2000

What third symbol in emission designation indicates cellular voice transmission?

E

ECE Board Exam November 1999

A term for a conventional land telephone line which is attached to the local telephone exchange by a pair of twisted copper wires.

Fixed wire

ECE Board Exam April 1999

A mobile telephone system, which used analogue cellular radio standard which was superceded by the Advanced Mobile Phone System in the US.

IMTS

ECE Board Exam November 1998

Refers to the duration occupancy period of call during its use.

Holding time

ECE Board Exam April 1998

How wide is the spectrum bandwidth of a single GSM carrier?

200 kHz

ECE Board Exam November 1997

The standard deviation of the variation in the transmission loss of a circuit should not exceed

1 dB

ECE Board Exam April 1997

One (1) Erlang is equal to ________.

36 CCS

ECE Board Exam April 2001

A type of call where cell cannot receive the supervisory audio tones in 5 seconds causing the cell site to turn the cell transceiver.

Call drop

ECE Board Exam November 2000

Telephone channel has a band-pass characteristics occupying the frequency range of ______

300 – 3400 Hz

ECE Board Exam April 2000

A digital mobile telephone system which called a European derivative of a Global System for Mobile Communication System operating at a higher frequency band.

DCS-1800

ECE Board Exam 1999

The receiving and transmission of printed materials over the telephone wires.

Facsimile

ECE Board Exam April 1999

One of the following central office switching equipment resistance limits refers to the longest subscriber loop length.

2000 ohms

ECE Board Exam April 1998

The modulation technique used by GSM cellular system

Gaussian Minimum Shift Keying

ECE Board Exam November 1997

Nominal voice channel

4 kHz

ECE Board Exam April 1997

Transmission of printed material over telephone lines

Facsimile

ECE Board Exam November 1996

What is the transmission rate of a GSM cellular system?

270 kbps

ECE Board Exam March 1996

A device to be connected across the headset in telephone receivers to reduce the effects of acoustic shock.

Two rectifiers in parallel with opposite polarities

ECE Board Exam April 2001

The signal quality of the cells is constantly monitored by the base station, when the quality of the calls drops below a certain specified level, the base request the MTSO to try and find a better cell site is referred as _________.

Hand – off

ECE Board Exam November 2000

In mobile communication such as the cellular service, the current maximum power is rated at __________

3 watts

ECE Board Exam April 2000

A special tone frequency which is transmitted by the mobile unit to cell site signaling call termination.

10 kHz

ECE Board Exam November 1999

This is the Nordic analogue mobile radio telephone system originally used in Scandinavia.

NMT

ECE Board Exam April 1999

An analogue mobile telephone system which was designed for United Kingdowm using 900 MHz frequency band.

TACS

ECE Board Exam April 1998

An interfering current in a telegraph or signaling channel due to telegraph or signaling current by another channel.

Cross fire

ECE Board Exam November 1997

What is the channel bandwidth of a standard analogue telephone system?

300 – 3400 Hz

ECE Board Exam April 1997

1 – CCS is equal to

100

ECE Board Exam March 1996

Crosstalk coupling is ___________

dBm (disturbing pair) minus dBm (disturbed pair).

the difference between readings on a cable pair with a tone and a cable pair without tone read at the far end of the cable.

signals from one circuit that get into another circuit

ECE Board Exam April 2001

Process of automatically changing frequencies as the mobile unit transfer into a different frequency zones so that the conversation can be continued in the new zone without redialing.

Hand-off

ECE Board Exam November 1996

What is the diameter of a copper wire to be used in a 16 km loop with a dc loop resistance of 100 ohms/km?

ECE Board Exam April 2001

Process of automatically changing frequencies as the mobile unit transfer into a different frequency zone so that the conversation can be continued in the new zone without redialing.

Hand-off

ECE Board Exam November 2000

A stage in cellular communication where voice channel is assigned to link up a call connection after a mobile or network originated a call.

Call completion

ECE Board Exam November 1999

How much approximate maximum power can a human voice possibly produce?

1 milliwatt

ECE Board Exam April 1999

A transmission facility connecting points 1 and 2 which is either permanent or temporary, normally voice grade facility provided by a public network provider.

Channel

ECE Board Exam April 1998

Best described as an amplifier used in radio telephony.

Class C

ECE Board Exam November 1997

Refers to the first generation of local loop system in telecommunication technology

Analogue cellular

ECE Board Exam April 1997

1 Erlang is ____________

1 TU

ECE Board Exam November 1996

Combination of modulator, channel and detector.

Discrete channel

ECE Board Exam March 1996

The local loop of the telephone system is understood to be

A two-wire or four-wire communication circuit between the customer’s premise and the central office.

ECE Board Exam November 1997

Refers to the first generation of local loop system in telecommunication technology

Analogue cellular

ECE Board Exam April 1997

_________ is used to measure speech volume

Volume unit meter

ECE Board Exam November 1996

What component in the telephone set has the primary function of interfacing the handset to the local loop?

Induction coil

ECE Board Exam March 1996

The ______ filter attenuates signals but passes frequencies below and above that band.

Band stop

ECE Board Exam November 1996

____________ is out-of-bound signaling between toll central offices (Bell System Standard)

3700 Hz

ECE Board Exam March 1996

In a telephone system, the customer’s telephone directory numbering is from 000 to 999, what is the capacity of the system?

1,000 lines

ECE Board Exam April 2001

How much signal-to-noise ratio is required to attain a satisfactory local exchange network?

35 dB

ECE Board Exam April 2000

What is the channel bandwidth of a standard analog telephone system?

300-3400 kHz

ECE Board Exam November 1996

A voice grade circuit using the PTN has an ideal passband of

0 to 4 kHz

ECE Board Exam November 1996

What kind of receiver is used in conventional telephone handset?

Electromagnetic

ECE Board Exam April 2001

In telecommunications the acronym NAM stands for

Numeric assignment module

ECE Board Exam November 2000

Referred as the reverse link channel of the cellular duplex system.

Mobile unit to cell

ECE Board Exam April 2000

Provides interface between the mobile telephone switching office and the mobile units

Cell site

ECE Board Exam November 1996

What is the power loss of a telephone hybrid?

3 Db

ECE Board Exam April 2001

This is small radio transceiver communication device which is normally wall mounted and where the WLL subscriber plugs its telephone handset.

Telephone wireless terminal

ECE Board Exam April 2000

A term used in wireless telegraphy and telephony to counter irregular disturbing radiation due to various causes which is produced by arc transmitter causing a rushing sound in receiving telephones.

Mush

ECE Board Exam November 1996

What is the phase delay of an 800 Hz voice signal if the phase shift is 15 deg.?

ECE Board Exam November 1996

A digital identification associated with a cellular system

SIM

ECE Board Exam April 2001

Component of a basic cellular system that provides interface between the switching office and the mobile units.
Cell site

ECE Board Exam November 2000

Which of the following cellular system is the only system allowed inside United States?

AMPS

ECE Board Exam April 2000

Which of the following system uses frequency band 825 – 845 MHz as a receive band of it base station?

Advanced Mobile Phone Services (AMPS)

The Telephone System (Blake C8)

        TRUE/FALSE

  1.   A telephone from 1930 could not work on today's public switched telephone network.

ANS:   F

  2.   The public switched telephone network is changing from an all analog to a mostly digital system.

ANS:   T

  3.   A LATA is a local calling area.

ANS:   T

  4.   A feature of the public switched telephone system is that calls cannot be "blocked".

ANS:   F

  5.   Telephones connect to the central office via trunk lines.

ANS:   F

  6.   The telephone switching hierarchy is being replaced by a "flat" network topology.

ANS:   T

  7.   Most local loops still use copper wire.

ANS:   T

  8.   A "twisted-pair" is twisted to minimize "crosstalk".

ANS:   T

  9.   The wires in a local loop are called TIP and GND.

ANS:   F

10.   In a local loop, the red wire is positive.

ANS:   F

11.   In a local loop, the TIP wire is positive.

ANS:   T

12.   Local loops can carry voice signals in only one direction at a time.

ANS:   F

13.   Local loops carry DC current.

ANS:   T

14.   Local loops carry signaling information.

ANS:   T

15.   Loading coils allow high-speed data loads to be carried on a local loop.

ANS:   F

16.   Typically, when a phone is on hook, a voltage of 48 volts appears across it.

ANS:   T

17.   When a telephone is off hook, the DC voltage across it can drop substantially from its on-hook value.

ANS:   T

18.   The DC resistance of a telephone is about 2000 ohms.

ANS:   F

19.   When a telephone is on hook, the DC current through it is in the range of 20 to 80 mA.

ANS:   F

20.   Touch-Tone is a registered trademark of AT&T.

ANS:   T

21.   DTMF is the same as Touch-Tone.

ANS:   T

22.   DTMF uses sets of 3 tones.

ANS:   F

23.   The technology to "dial" telephone numbers was invented in 1893.

ANS:   T

24.   A crosspoint switch allows any incoming line to be connected to any outgoing line.

ANS:   T

25.   The central office uses 24 volts AC at 20 hertz to cause a telephone to ring.

ANS:   F

26.   The local-loop is full-duplex.

ANS:   T

27.   Telephones usually contain a hybrid coil or an equivalent circuit.

ANS:   T

28.   To allow for "sidetone", a hybrid coil should be slightly unbalanced.

ANS:   T

29.   The signal levels in analog telephone systems have increased substantially over the past 100 years.

ANS:   F

30.   The signal levels in modern analog telephone systems are still based on 19^th-century technology.

ANS:   T

31.   To allow multiplexing, the bandwidth of voice-grade telephone signals is deliberately restricted.

ANS:   T

32.   The net gain of a telephone system must be greater than 0 dB for an acceptable signal level.

ANS:   F

33.   Too much gain in a telephone system causes "singing".

ANS:   T

34.   Echo suppressors prevent oscillations on long-distance telephone circuits.

ANS:   T

35.   Echo suppressors can be switched off by a subscriber's equipment.

ANS:   T

36.   C-message weighting increases the bandwidth of a local loop.

ANS:   F

37.   The reference level for measuring noise in a telephone system is 10^–12 Watts.

ANS:   T

38.   In a telephone system, signal strength is given relative to the zero transmission loss point.

ANS:   T

39.   TDM is being replaced by the newer FDM technology in telephone systems.

ANS:   F

40.   DS-1 can be used to carry digital data that did not originate as a voice signal.

ANS:   T

41.   When using DS-1 to carry data, it is common to use each channel to carry 64 kbps.

ANS:   F

42.   Digital carriers up to T3 can use copper wires.

ANS:   F

43.   A DS-1C signal carries twice as many channels as a DS-1 signal.

ANS:   T

44.   A DS-1C signal uses twice the bit rate of a DS-1 signal.

ANS:   F

45.   "Stuff" bits are used to compensate for differences in clock rates.

ANS:   T

46.   Every "in-channel" signal is also an "in-band" signal.

ANS:   F

47.   Common-channel signaling is being replaced by the more modern MF signaling.

ANS:   F

48.   Common-channel signaling reduces opportunities for stealing telephone service.

ANS:   T

49.   ADSL is faster than ISDN.

ANS:   T

50.   B-ISDN is a slower version of standard ISDN.

ANS:   F

       MULTIPLE CHOICE

  1.   DTMF stands for:

a.	Digital Telephony Multiple Frequency	c.	Dual-Tone Multifrequency
b.	Dial Tone Master Frequency	d.	Digital Trunk Master Frequency

ANS:   C

  2.   PSTN stands for:

a.	Public Switched Telephone Network	c.	Primary Service Telephone Network
b.	Private Switched Telephone Network	d.	Primary Service Telephone Numbers

ANS:   A

  3.   POTS stands for:

a.	Private Office Telephone System	c.	Primary Operational Test System
b.	Primary Office Telephone Service	d.	Plain Old Telephone Service

ANS:   D

  4.   LATA stands for:

a.	Local Access and Transport Area	c.	Local Area Telephone Access
b.	Local Access Telephone Area	d.	Local Area Transport Access

ANS:   A

  5.   A LATA is a:

a.	a local calling area	c.	a way of accessing a tandem office
b.	a type of digital local network	d.	a way of accessing a central office

ANS:   A

  6.   Central offices are connected by:

a.	local loops	c.	both a and b
b.	trunk lines	d.	none of the above

ANS:   B

  7.   Local loops terminate at:

a.	a tandem office	c.	a central office
b.	a toll station	d.	an interexchange office

ANS:   C

  8.   Call blocking:

a.	cannot occur in the public telephone network
b.	occurs on the local loop when there is an electrical power failure
c.	occurs only on long-distance cables
d.	occurs when the central office capacity is exceeded

ANS:   D

  9.   In telephony, POP stands for:

a.	Post Office Protocol	c.	Power-On Protocol
b.	Point Of Presence	d.	none of the above

ANS:   B

10.   The cable used for local loops is mainly:

a.	twisted-pair copper wire	c.	coaxial cable
b.	shielded twisted-pair copper wire	d.	fiber-optic

ANS:   A

11.   FITL stands for:

a.	Framing Information for Toll Loops	c.	Framing In The Loop
b.	Fiber In the Toll Loop	d.	Fiber-In-The-Loop

ANS:   D

12.   Loading coils were used to:

a.	increase the speed of the local loop for digital data
b.	reduce the attenuation of voice signals
c.	reduce crosstalk
d.	provide C-type conditioning to a local loop

ANS:   B

13.   DC current flows through a telephone:

a.	when it is on hook	c.	as long as it is attached to a local loop
b.	when it is off hook	d.	only when it is ringing

ANS:   B

14.   The range of DC current that flows through a telephone is:

a.	20 mA to 80 mA	c.	2 mA to 8 mA
b.	200 mA to 800 mA	d.	20 mA to 80 mA

ANS:   D

15.   The separation of control functions from signal switching is known as:

a.	step-by-step switching control	c.	common control
b.	crossbar control	d.	ESS

ANS:   C

16.   The typical voltage across a telephone when on-hook is:

a.	48 volts DC	c.	90 volts DC
b.	48 volts, 20 hertz AC	d.	90 volts, 20 hertz AC

ANS:   A

17.   The typical voltage needed to "ring" a telephone is:

a.	48 volts DC	c.	90 volts DC
b.	48 volts, 20 hertz AC	d.	90 volts, 20 hertz AC

ANS:   D

18.   The bandwidth of voice-grade signals on a telephone system is restricted in order to:

a.	allow lines to be "conditioned"	c.	allow signals to be multiplexed
b.	prevent "singing"	d.	all of the above

ANS:   C

19.   VNL stands for:

a.	voltage net loss	c.	via net loss
b.	volume net loss	d.	voice noise level

ANS:   C

20.   Signal loss is designed into a telephone system to:

a.	eliminate reflections	c.	improve signal-to-noise ratio
b.	prevent oscillation	d.	reduce power consumption

ANS:   B

21.   The reference noise level for telephony is:

a.	1 mW	c.	1 pW
b.	0 dBm	d.	0 dBr

ANS:   C

22.   The number of voice channels in a basic FDM group is:

a.	6	c.	24
b.	12	d.	60

ANS:   B

23.   Basic FDM groups can be combined into:

a.	supergroups	c.	jumbogroups
b.	mastergroups	d.	all of the above

ANS:   D

24.   In telephone system FDM, voice is put on a carrier using:

a.	SSB	c.	PDM
b.	DSBSC	d.	PCM

ANS:   A

25.   PABX stands for:

a.	Power Amplification Before Transmission
b.	Private Automatic Branch Exchange
c.	Public Automated Branch Exchange
d.	Public Access Branch Exchange

ANS:   B

26.   SLIC stands for:

a.	Single-Line Interface Circuit	c.	Subscriber Line Interface Card
b.	Standard Line Interface Card	d.	Standard Local Interface Circuit

ANS:   C

27.   In DS-1, bits are "robbed" in order to:

a.	provide synchronization	c.	cancel echoes
b.	carry signaling	d.	check for errors

ANS:   B

28.   "Bit-stuffing" is more formally called:

a.	compensation	c.	justification
b.	rectification	d.	frame alignment

ANS:   C

29.   ISDN stands for:

a.	Integrated Services Digital Network	c.	Integrated Services Data Network
b.	Information Services Digital Network	d.	Information Systems Digital Network

ANS:   A

30.   Basic ISDN has not been widely adopted because:

a.	it took to long to develop
b.	it is too slow
c.	it has been surpassed by newer technologies
d.	all of the above

ANS:   D

31.   ADSL stands for:

a.	All-Digital Subscriber Line	c.	Allocated Digital Service Line
b.	Asymmetrical Digital Subscriber Line	d.	Access to Data Services Line

ANS:   B

32.   Compared to ISDN, internet access using ADSL is typically:

a.	much faster	c.	much more expensive
b.	about the same speed	d.	none of the above

ANS:   A

        COMPLETION

  1.   A ____________________ is a local calling area.

ANS:   LATA                      

  2.   Central offices are connected together by ____________________ lines.

ANS:   trunk                        

  3.   One central office can be connected to another through a ____________________ office.

ANS:   tandem                     

  4.   With 7-digit phone numbers, ____________________ thousand telephones can connect to a central office.

ANS:   ten                           

  5.   Call ____________________ is when it becomes impossible for a subscriber to place a call due to an overload of lines being used.

ANS:   blocking                   

  6.   New ____________________ switching equipment uses TDM to combine signals.

ANS:   digital                       

  7.   Most local loops still use ____________________ copper wire.

ANS:   twisted-pair              

  8.   As compared to a hierarchical network, a ____________________ network never needs more than one intermediate switch.

ANS:   flat                           

  9.   ____________________ coils were used to reduce the attenuation of voice frequencies.

ANS:   Loading                   

10.   In a twisted-pair telephone cable, the red wire is called ____________________.

ANS:   ring                          

11.   In a twisted-pair telephone cable, the green wire is called ____________________.

ANS:   tip                            

12.   Of the red and green 'phone wires, the ____________________ wire is positive with respect to the other.

ANS:   green                        

13.   A telephone is said to have ____________________ the line when the central office sends it dial tone.

ANS:   seized                      

14.   The ____________________ functions are provided by a SLIC.

ANS:   BORSCHT               

15.   A ____________________ coil prevents loss of signal energy within a telephone while allowing full-duplex operation over a single pair of wires.

ANS:   hybrid                      

16.   In a crosspoint switch, not all ____________________ can be in use at the same time.

ANS:   lines                         

17.   The old carbon transmitters generated a relatively ____________________ signal voltage.

ANS:   large                         

18.   The generic term for Touch-Tone^® signaling is ____________________.

ANS:   DTMF                      

19.   A ____________________ line provides more bandwidth than a standard line.

ANS:   conditioned              

20.   In the telephone system, amplifiers are called ____________________.

ANS:   repeaters                  

21.   An echo ____________________ converts a long-distance line from full-duplex to half-duplex operation.

ANS:   suppressor               

22.   ____________________ weighting is an attempt to adjust the noise or signal level to the response of a typical telephone receiver.

ANS:   C-message               

23.   In FDM telephony, the modulation is usually ____________________.

ANS:  

SSB

SSBSC

24.   In FDM telephony, ____________________ bands separate the channels in a group.

ANS:   guard                       

25.   Because of "bit robbing", a channel in a DS-1 frame allows only ____________________ kbps when used to send digital data.

ANS:   56                            

26.   A ____________________ is a group of 12 DS-1 frames with signaling information in the sixth and twelfth frames.

ANS:   superframe              

27.   In DS-1C, ____________________ bits are used to compensate for differences between clock rates.

ANS:   stuff                         

28.   Busy and dial tone are referred to as ____________________ signals because they use the same pair of wires as the voice signal.

ANS:   in-channel                

29.   SS7 is the current version of _________________________ signaling.

ANS:   common-channel     

30.   SS7 is a ____________________-switched data network.

ANS:   packet                      

31.   In ISDN, the ____________________ channel is used for common-channel signaling.

ANS:   D                             

32.   In ISDN, the ____________________ channels are used for voice or data.

ANS:   B                              

33.   Terminal equipment especially designed for ISDN is designated ____________________ equipment.

ANS:   TE1                          

34.   The A in ADSL stands for ____________________.

ANS:   asymmetrical           

35.   In ADSL, the speed from the network to the subscriber is ____________________ than the speed in the opposite direction.

ANS:  

greater

faster

       SHORT ANSWER

  1.   For a certain telephone, the DC loop voltage is 48 V on hook and 8 V off hook. If the loop current is 40 mA, what is the DC resistance of the local loop?

ANS:  

1000 ohms

  2.   For a certain telephone, the DC loop voltage is 48 V on hook and 8 V off hook. If the loop current is 40 mA, what is the DC resistance of the telephone?

ANS:  

200 ohms

  3.   Which two DTMF tones correspond to the digit "1"? (Use the table in the text.)

ANS:  

697 Hz and 1209 Hz

  4.   Calculate the dB of VNL required for a channel with a 3 ms delay.

ANS:  

1 dB

  5.   If a telephone voice signal has a level of 0 dBm, what is its level in dBrn?

ANS:  

90 dBrn

  6.   A telephone test-tone has a level of 80 dBrn at a point where the level is +5dB TLP. If C-weighting produces a 10-dB loss, what would the signal level be in dBrnc0?

ANS:  

65 dBrnc TLP