This is the Section 5 Module 1 of the compiled Communications Coaching Materials taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize each questions to increase the chance of passing the ECE Board Exam.
Communications Engineering Coaching: Section 5 Module 1
# |
Questions |
Answers |
1 |
Amplitude modulation via Facsimile |
A3C |
2 |
Frequency modulation via Facsimile |
F3C |
3 |
What emission is F3C? |
Facsimile |
4 |
Troposcatter in Sky Wave Propagation occurs in what range of frequency |
300 MHz to 3 GHz |
5 |
Which of the following terrain types permits a ground wave to travel the farthest? |
Salty |
6 |
What of the following permits a microwave signal to travel in one direction with virtually no loss, but severely attenuates any signal attempting to travel in the reverse direction? |
Isolator |
7 |
Ferrite rod device that prevents the formation of reflected waves |
Isolator |
8 |
Advantage of Trap Antenna |
It can be use in different antenna because of LC circuit |
9 |
In Pulse Width Modulation, |
pulse duration |
10 |
varying pulses |
pulse width modulation |
11 |
Expose ground equipment should not exceed ____ Vrms |
45 |
12 |
Typical earth factor |
4/3 |
13 |
Directivity is |
Proportional to Antenna gain |
14 |
Current node in a half wave antenna is located |
at the ends |
15 |
Voltage node in a half wave antenna is located |
at the feed |
16 |
from zero modulation to 100% modulation, |
Antenna current increases by 22.5 % |
17 |
The standard reference antenna for a directive gain is |
Isotropic Antenna |
18 |
How much farther does the radio path horizon distance exceeds the geometric horizon? |
Increases by about 15% of the length |
19 |
Parasitic element |
5% longer |
20 |
use in aircraft |
Frequency modulated continuous wave |
21 |
Antenna use in ILS |
folded dipole continuous wave |
22 |
Why is nitrogen gas sometimes used in waveguide? |
to keep the waveguide dry |
23 |
Need for pressurizing cable with dry air |
to prevent internal arcing |
24 |
As electromagnetic travel in free space, only one if the following can happen to them |
Attenuation |
25 |
Which of the following is not a natural ways of radio wave may travel from transmitter to receiver? |
Microwave |
26 |
hollow conductor that carries RF |
Waveguide |
27 |
Telephone |
13 kbps |
28 |
In a ¾ wavelength shorted at end will have impedance |
Infinite |
29 |
What is major cause of atmospheric or static noise? |
Thunderstorms |
30 |
What signal to noise ratio is required for satisfactory telephone service? |
50 dB |
31 |
In SSB, carrier and the other sideband is being |
cancel, filter |
32 |
IBM |
83B |
33 |
folded dipole compared to simple dipole |
longer |
34 |
In CCITT’s FDM Hierarchy, number of channels in a master group |
300 |
35 |
Power HF compared to UHF |
100:20 |
36 |
The third symbol used for television transmission |
F |
37 |
A word in telegraphy consists of ___ characters plus a word space |
7 and ½ |
38 |
VOR |
108.1 to 117.95 MHz |
39 |
Class D AM |
12 Midnight to 5 AM |
40 |
Trap antenna |
can be use in wideband |
41 |
What is the typical speech coding rate used for GSM? |
13 kbps |
42 |
D-AMPS |
8 kbps |
43 |
Difference between available power and power budget |
Power Margin |
44 |
Maximum number of break in a 60 minute show |
7 |
45 |
2.5:1 |
|
46 |
Unmodulated carrier |
0% modulation |
47 |
Frequency band of U600 |
564-3084 |
48 |
What is the transmission rate of a T3 line? |
44.736 Mbps |
49 |
in telephone, maximum pulse per second |
6 |
50 |
third symbol emission for telephone |
E |
51 |
Monochromatic |
one color and one |
52 |
Quality |
Contrast |
53 |
To couple energy into and out of a waveguide |
use thin piece of wire as an antenna |
54 |
A high standing wave ratio might be caused by |
impedance mismatch |
55 |
VHF received from 500 miles |
tropospheric ducting |
56 |
Oldest multiplexing scheme |
Space Division Multiplexing |
57 |
1st Active Satellite |
Sputnik 1 |
58 |
1st Satellite to Transmit and Receive |
Intelsat 1 |
59 |
Primetime block of TV |
6 PM to 11 PM |
60 |
Determine from the following radio frequency that falls under the very high frequency band of radio spectrum |
235.50 MHz |
61 |
Antenna power times the Antenna gain |
Effective Radiated Power (ERP) |
62 |
Antenna power times the Antenna gain relative to Isotropic antenna |
Effective Isotropic Radiated Power (EIRP) |
63 |
Factors |
Antenna height, distance |
64 |
It is the picture quality determined by the difference of the intensity between black and white parts of the picture |
Contrast |
65 |
Pilot tone |
3000 Hz |
66 |
GMA 7 |
High VHF |
67 |
Amount of voltage induced in a wave by an EM wave |
Proportional to Field Strength |
68 |
Disadvantage of Trap antenna |
It radiates harmonics |
69 |
An instrument used to measure the relevant height, a layer in the ionosphere used for wave propagation |
Ionosonde |
70 |
Third symbol of emission designation using telephone (telephony) such as in sound broadcasting |
E |
71 |
Capacitor |
Capacitor |
72 |
Commonly used insulator |
Mica |
73 |
Distance to the station, DME |
Slant distance |
74 |
What phenomenon causes of longer radio path to exceed geometric horizon? |
Refraction |
75 |
Waveguide construction |
should not have a long horizontal run |
76 |
Loading coil is used in marconi |
tuning out capacitance reactances |
77 |
Last stage of GSM |
EDGE |
78 |
Bandwidth of fiber optics compared to cable |
100 times |
79 |
What causes the attenuation in waveguide? |
losses in the conducting walls |
80 |
Continuous tone generated by the combination of two frequencies of 350 Hz and 440 Hz used in telephone sets |
Call Waiting tone |
81 |
Pulse dialing rate |
10 pulses/sec |
82 |
What kind of receiver is used in conventional telephone handset? |
Electromagnet |
83 |
Characteristic impedance is dependent on |
length |
84 |
Velocity of sound |
330 m/s |
85 |
Time for the signal to travel |
Propagation delay |
86 |
How many voice band channels in a SPADE FDMA satellite system are PCM encoded before they separately modulate the assigned carrier? |
800 |
87 |
AMPS operated in which cellular radio frequency? |
800 MHz |
88 |
Which of the following represents the best standing wave ratio? |
1:1 |
89 |
The _____ of a sound is a subjective effect which is a function of the ear and brain |
loudness |
90 |
OMEGA measures |
phase angle |
91 |
LORAN |
measures at larger distance |
92 |
Radiation resistance |
equivalent resistance that will dissipate the same amount |
93 |
What antennas are suitable for direct connection to a waveguide? |
Horn and slot antenna |
94 |
What factors determines the EIRP required by a station in each operation? |
Satellite antennas and height, Satellite receiver sensitivity |
95 |
Ferrite beads |
use in primary and secondary |
96 |
aircracft radio altimeter |
4250 MHz to 4350 MHz |
97 |
end impedance of half-wave dipole |
2500 ohms |
98 |
aircraft VHF communication |
118.00 MHz to 139.975 MHz |
99 |
The bending of radio waves passing over the top of a mountain range that disperses a weak portion of the signal behind the mountain is |
knife-edge diffraction |
100 |
troposcatter |
beyond 5000 km |
101 |
Information about satellite send to earth |
TTC |
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