COMMUNICATIONS ENGINEERING PART 9 TELEPHONY Multiple Choice. Choice. Encircle the letter which which corresponds to your answer. 1.
In International International Telephone Telephone Numbering, Numbering, a digit digit or combination combination of digits characterizing the called numbering area within a country is called ______ code. a. local b. CCITT c. Baudot d. Area
2.
The last two digit digit of the loaded cable designation designation 22E66 indicates a. b. c. d.
3.
A condition of a telephone telephone handset, in which itit can be called, called, is _______condition. _______condition. a. b. c. d.
4.
spacing coil inductance wire gauge attenuation
on-hook off-hook busy none of these
When digits 3 is dialed using touch tone system, the amount of time needed to send the tone is a. b. c. d.
0.1 sec 50 msec 0.25 sec 0.25 usec
5. A telephone number perform the following operations except a. To route the call b. To activate the necessary necessary apparatus for proper call charging
c. d.
To order clearing of connection None of the above
6. The number to be be dialed or called called to reach a subscriber in the same local network or numbering area is a. b. c. d.
Local Code Area code Toll access Code Subscriber No.
7. That part of the telephone telephone network between between the telephone telephone instrument at the subscriber premises and the central office equipment is called the __________ a. b. c. d.
Inter-office trunk Tie Line Subscriber loop Service drop wire
8. A line linking telephone Central Offices is is called called _________ _________ line. a. Tie b. Inter- office trunk c. Routing d. Connector 9. A signaling signaling technique technique wherein wherein a number of voice paths paths is carried over one common channel instead of having individual voice channels a. b. c. d.
In band singnaling Out of band singnaling Common channel singnaling Alternate channel singnaling
10. ________is a unit of telephone traffic defined as one user making a call of one second duration. a. b. c. d.
CCS Call-second Erlangs Call-hour
11. During a busy hour in a telephone system an average of one call is lost, then the grade of service is considered to be: a. 1.01 b. 10% c. 0.10% d. 0.01 12. If a busy counts are made during the span of 15 minutes, and the average number of occupied circuit is found to be 8, then the traffic, in Erlang, is: a. b. c. d.
2 8 6 4
13. In a standard CCITT group, 12 channels FDM, the carrier frequency of channel No. 1 is ____________ a. b. c. d.
100 kHz 104 kHz 108 kHz 60 kHz
14. In the FDM hierarchy, a mastergroup is composed of ten supergroups and is equivalent to a. b. c. d.
600 Channels 60 Channels 180 Channels 120 Channels
c. d.
A or B A and B
17. This refers to loop AC reference frequency measured in decibels a. b. c. d.
Signaling limits Resistance limit Attenuation limit All of these
18. An induction coil which is a multiple winding transformer intended to interface a 2-wire circuit to a 4-wire circuit to permit two-way transmission of signals. a. b. c. d.
hybrid function speech transformer transmission regulation circuit A or B
19. A subscriber loop signaling method in which signaling information is indicated by the presence and absence of a battery and ground condition on the line at the called end of the trunk. a. Wet – Dry b. Reverse Battery c. High - Low d. Supervisory 20. An arrangement where the only possible connection between a number of exchanges is through a single tandem or transit exchange where they are all connected.
15. The approximation process in PCM creates noise called: a. b. c. d.
Thermal White Noise Quantizing Noise Agitation Noise
16. The criteria to be considered in designing a telephone system a. Attenuation limit b. Resistance limit
a. b. c. d.
mesh star composite ring
21. CCITT recommendation E-161 recommends that not more than _____ digits make up an international number, excluding the international prefix. a. 10 b. 12 c. 16 d. 20 22. The following are the transmission media used for telephone systems except: a. b. c. d.
parallel wire coaxial cable fiber optics NOTA
26. For crosstalk to be considered intelligible, at least _____ words are intelligible to the listener in a seven second period. a. b. c. d.
5 6 4 3
27. Noise that is non-continuous, consisting of irregular pulses or noise spikes of short duration and of relatively high amplitude. a. b. c. d.
Solar Intermodulation Impulse Crosstalk
23. The subscriber loop provides the following except: a. b. c. d.
talk battery ringing voltage telephone dial current during on hook
24. A method of multiplexing in which the total frequency spectrum available is used by each channel, but only f or part of the time. a. b. c. d.
FDM TDM SDM GSM
28. The signal to noise ratio for voice based on customer satisfaction is a. b. c. d.
30 dB 45 dB 15 dB 20 dB
29. dBa is a noise unit which uses a tone of 1000 Hz and a power level of a. -85 dBm b. -90 dBm c. 85 dBm d. -80dBm
25. The primary cause of echo and singing is a. b. c. d.
intermodulation noise crosstalk impedance mismatch thermal noise
30. The average intensity in one or more traffic paths occupied in the busy hour by one 2-minute call or for an aggregate duration of two minutes. a. b. c. d.
CCS Cm Erlang EBHC
31. A method of handling lost calls wherein a call failing to immediately find a server, waits enters a queue until one becomes available. a. b. c. d.
Lost Calls Cleared Lost Calls Held Lost Calls Delayed NOTA
32. The main terminal used as cross connection point for cables 300 pairs and above. a. b. c. d.
MTTC MDF DP TTC
36. An electronic circuit which is inserted into the 4-wire trunk path effectively to block the passage of reflected signal energy. a. b. c. d.
echo suppressor loading coil loop extender telephone amplifier
37. The following are signaling functions except: a. ringing signals b. address signals c. supervisory signals d. NOTA 38. The standard spacing for 19-D-88 cable loading code is
33. For PCM, the sampling theorem states that the sampling frequency must be ________ the highest frequency contained in the analog signal. a. b. c. d.
twice more than twice less than twice equal to
34. A group of sixty voice grade channels with a bandwidth of 240 KHz is called a a. b. c. d.
group supergroup mastergroup jumbogroup
35. On the subscriber's telephone set employing the touch tone technique, how many signals are transmitted to the telephone exchange for every button that is pressed? a. b. c. d.
2 VHF signals 1 VHF and 1 AF 2 AF tones 16 AF tones
a. b. c. d.
700 ft. 6000 ft. 4500 ft. 3000 ft.
39. A telephone exchange has a subscriber loop limit of 1800 ohms, excluding the telephone instrument. What is the farthest distance, in miles, that a subscriber can be located away from the telephone exchange, if AWG 26 cable, which has a resistance of 431 ohms/loop mile, is used? a. b. c. d.
5.95 8.18 3.9 4.18
40. The Strowger or step-by-step system falls under what type of switching control system? a. b. c. d.
Manual Progressive Common automatic
41. For building telephone facilities, the size of entrance conduit shall not be less than _______ in diameter. a. b. c. d.
47. The voice frequency channel pass band is: a. b. c. d.
30 mm 50 mm 60 mm 75 mm
42. In telephony, tone dialing takes _________ time than pulse dialing.
0 to 4000 Hz 300 to 3000 Hz to carry only speech all of the preceding
48. What is used to transmit more than one conversation over a path? a. hybrid b. tandem c. multiplexing d. all of the above
a. less b. more c. about the same d. can’t be determined
49. The common channel interoffice signaling method 43. A telephone service wherein calls are rerouted into a preassigned station is called ____________. a. b. c. d.
Camp-On Call Forwarding Call Barring Abbreviated Dialing
a. b. c. d.
uses the same channel for signaling as for the related conversation is used on local loops uses a separate channel for signaling only comes the signaling for one related conversation
50. Telephone switching is accomplished by 44. What t ype of operating? a. b. c. d.
control system
Crossbar switches are
Manual Progressive Common automatic
45. PABX stands for a. b. c. d.
Private All-purpose Broadcasting Exchange Private Automatic Branch Exchange Public Access Bidirectional Exchange Public Address Broadcasting Exchange
46. A trunk is a. the base of a communication tower b. a telephone line connecting two C.O.’s c. a line connecting one telephone set to the PABX d. the structure where antenna are attached
a. b. c. d.
Manual Switchboard Step-by-step Switches Crossbar switches Any of the preceding
51. The step-by-step switch a. b. c. d.
was invented by Strowger generates much noise operates using a system of electromechanical switches all of these
52. The telephone was invented by a. b. c. d.
James Watson Alexander Graham Bell Philip Reis Almon Strowger
53. A switching network capable of providing a path from every inlet link to every outlet link in the absence of traffic. a. b. c. d.
Concentration Blocking Full availability switch Crosspoint
54. An exchange primarily used as a switching point for traffic between other exchanges is a. Transfer system b. Transit Exchange c. Connecting Point d. Tandem Exchange 55. A telephone switch is an example of ____ switching a. b. c. d.
packet message circuit virtual circuit
58. A telephone switching system with a capacity of 100 lines could assign telephone numbers from a. b. c. d.
0001 – 1000 000-999 0000-1000 001 – 999
59. The following are the building blocks of a Step-by-Step Switching System except: a. b. c. d.
marker linefinder selector connector
60. Which has longer subscriber loop length, the Central Office Switching equipment having a resistance limit of a. b. c. d.
500 ohms 1000 ohms 1500 ohms 2000 ohms
56. The local loop of a telephone system is 61. A fax transmission is usually at a _______ mode. a. a two-wire communication circuit between a customer’s premise and the central office b. a group of wires connecting a telephone set to a modem c. a four wire circuit connecting a fax machine to a computer d. a single piece of wire connecting the subscriber’s telephone to another telephone set. 57. Identical telephone numbers in different parts of the country are distinguished by their a. b. c. d.
access codes country codes trunk prefixes area codes
a. simplex b. half-duplex c. full duplex d. multiplex 62. A permanent circuit for private use within a communications network a. b. c. d.
two –wire 4-wire switched leased
63. The class of exchange with the primary function of connecting central offices when a direct trunk is not available. a. b. c. d.
local gateway toll tandem
68. The minimum size for an entrance conduit for building telephone facilities. a. b. c. d.
50 mm 50 cm 65 mm 65 cm
69. The size of entrance conduit for a 100 pair entrance cable. 64. Dial tone, busy tone and ring back tones are examples of _______ signals. a. b. c. d.
supervisory address musical digital
65. How much time in seconds is saved if we use Touch Tone Dialing instead of Pulse Dialing to call telephone number 781-10-05? a. b. c. d.
3.55 7.75 7.55 7.15
66. With attenuation limit at 6 dB, what is the length of cable using gauge 26 with attenuation of 1.61 dB per km. a. b. c. d.
1.3 km 4.7 km 3.7 km 2.5 km
67. The maximum length for 1300-ohm signaling or loop resistance using AWG No. 26 wire with 133.9 ohm per km. a. b. c. d.
5.2 km 4.7 km 7.5 km 9.7 km
a. b. c. d.
50 mm 65 mm 75 mm. 100 mm.
70. The backboard color for the house or riser cable. a. b. c. d.
yellow white blue red
71. The maximum span from telephone pole to the building for an aerial entrance cable. a. b. c. d.
30 m 600 mm 45 m 5.5 m
72. The sampling period for telephone signals. a. b. c. d.
8000 Hz. 125 µsec. 6400 Hz. 100 µsec.
73. The inability to interconnect two idle lines connected to a switching network due to all possible paths are in use. a. Concentration b. Blocking c. Full availability d. Crosspoint
74. The minimum depth for an underground entrance conduit under areas used for vehicular traffic inside private property. a. b. c. d.
300 mm 600 mm 50 mm 1m
75. The minimum clearance for aerial entrance cables over areas accessible to pedestrians is a. b. c. d.
4.5 m 5.5 m 3.5 m 6.5 m
80. The name of the device invented by Johann Philipp Reis in 1860 which could transmit a musical tone over a wire to a distance point. a. harmonic telegraph b. phonograph c. telephone d. radio 81. When was the first complete sentence ever transmitted by the telephone? a. b. c. d.
1860 1876 1892 1905
76. The steel gauge of the outdoor MTTC. a. b. c. d.
16 18 20 22
77. PAM is: a. b. c. d.
a pulse system immune from noise a digital system a popular system for telephone transmissions an analog system
78. A suitable sampling rate for a signal containing frequency components between 40 Hz and 4 k Hz would be: a. b. c. d.
10 kHz 80 Hz 90 Hz 4.04 kHz
79. Quantization noise can be reduced by: a. b. c. d.
taking samples at a faster rate using a PCM system increasing the number of standard amplitude using higher amplitude signals
82. Who invented the first practical system for the electrical switching of calls installed in 1892? a. b. c. d.
Bell Watson Edison Strowger
83. What part of the conventional telephone set the transmitter and receiver unit are located? a. b. c. d.
dial base keypad handset
84. The type of transmitter widely used in the conventional telephone set. a. b. c. d.
carbon ceramic piezoelectric electromagnetic
85. Who invented the first carbon type transmitter? a. b. c. d.
c. d.
Bell Watson Gray Edison
91. What is the standard bandwidth of voice channel according to CCITT recommendations?
86. The type of receiver widely used in the conventional telephone set. a. b. c. d.
electromagnetic ceramic carbon piezoelectric
2 4 7 12
88. In the telephone industry, performed by a. b. c. d.
a. b. c. d.
a. b. c. d.
BORSCHT functions
are
subscriber line interface cross point matrix switching network connector switch
a. b. c. d.
dial tone side tone echo singing
90. The type of dialing possible for telephone set with rotary dial.
dial tone ringing tone busy tone congestion tone
94. BORSCHT stands for a.
a. tone dialing b. pulse dialing
dial tone ringing tone busy tone congestion tone
93. The signal heard on the telephone line which indicates that the called subscriber set is in use.
89. In the telephone unit, what is produced when the balancing network in a hybrid circuit is intentionally unbalanced slightly so that small amount of transmitted signal is fed to the receiver of the talking phone? a. b. c. d.
300 – 3.4 KHz 200 – 3.3 KHz 20 – 20 KHz 30 – 30 KHz
92. The signal heard on the telephone line that indicates readiness of the central office in receiving address or telephone number.
87. How many unique tones are used for the 12-key dual-tone multifrequency keypad? a. b. c. d.
loop dialing e & m dialing
b. c. d.
battery, over-voltage protection, ringing, supervision, coding, hybrid and testing battery, on-hook, regulator, surge protect, circuit, hybrid and test name of a leading manufacturer of telephone system acronym for the developers of computer
95. Request for service from the telephone is detected at the Central Office as a. b. c. d.
dial pulses ringing signal flow of loop current battery reversal
96. The location where all subscriber lines are terminated and switching equipment facility is installed. a. b. c. d.
central office toll office gate way tandem
97. A private line communications channel of the type provided by communication common carrier for linking two or more points together. a. b. c. d.
party line tie line DID line Trunk line
98. The attenuation loss limit of the subscriber loop is set at 6 dB. What is the maximum length if a 26H88 loading coil with an attenuation of 0.80 dB per kilometer is added? a. b. c. d.
1.5 km 3.5 km 5.5 km 7.5 km
99. The first number of the loaded cable designation 19H44 indicates a. b. c. d.
spacing coil inductance wire gauge attenuation
100. The letter of the loaded cable designation 24B88 indicates a. b. c. d.
spacing coil inductance wire gauge attenuation
