(Last Updated On: December 8, 2017)
This is the Section 1 Module 5 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 1 Module 5
QUESTIONS |
ANSWERS |
In TV, the picture information is transmitted on a separate carrier that is located _____ lower in frequency that the sound carrier |
4.5MHz |
Which of the standards given below is a terrestrial digital TV transmission |
8-VSB |
What is the main accelerating element in the CRT |
ultor |
What is the combined mixer and LO that uses 1 transistor of tube or both |
Antodyne converter |
Lossless compression scheme generally look for redundancies in the data for instance the string of zeroes can be replaced with a code that tells the receivers the length of the string. What do you call this technique? |
Run length encoding |
Which ground based navigation system has a center frequency of 108-118MHz |
VOR or DME |
All colors on the color test signal are modulated at 75% except what color? |
Gray |
In analog cellular system, the interfering signal strength remains approximately less than ____ of desired signal strength to assure negligible interference |
2% |
What is the approximate critical frequency of E layer? |
4MHz |
The 10 base T Ethernet system is restricted only to ______ |
100m |
What code is used in 100 days Tx Ethernet standard? |
3 level Manchester code |
What is the carrier frequency of supergroup 10? |
3100kHz |
What frequency is used to signal handoffs to another cell and the termination of the cell in cellular communications |
10kHz |
Which of the following principle musical intervals is considered desonant? |
7:8 |
What is essentially a cell site shelter that is mounted on flat bed tractor trailer used for emergency purposes |
COW |
In cellular system what defines the geographic distance that is required between cells used in identical frequencies in order to avoid interference between the radio transmissions of this cells? |
Distance-to-reuse ratio (D/R) |
RA 9292 was approved by Pres. Gloria Macapagal Arroyo on what date? |
April 17, 2004 |
Which of the following is considered the first instance of government regulation of radio technology? |
Radio act of 1910 |
What do you call the random data send continuously by the NIC that disrupts the whole area network? |
Jabber |
What law regulates the operation of cable antenna system in the Phil? |
EO 205 |
Which of the following is the nearest star to the solar system? |
Proxima Centauri |
What is the shifting of antenna pattern so that the major lobe is at an angle below the horizontal? |
Down tilt |
What allows one antenna to be used for reception and transmission without mutual interference? |
Duplexer |
What is the term used to describe an ordinary voice telephony? |
POTS |
What do you call the call that cannot be completed because of the central office or PBX switching capacity is full at the time the call attempted? |
Block call |
Why does an FM antenna ammeter not change with modulation? |
No power added with modulation |
What is meant by peak white? |
The video signal represents max luminance |
In color CRT, what refers to adjustment of the three electron beam so that each lens can phosper dots on the appropriate color? |
Purity |
In a satellite system, what do you call the focus beam of energy that covers a relatively small area on the earth produced by high gain antenna on the satellite? |
Spot beam |
What radio system was developed to provide high speed packet data access for the GSM network? |
GPRS |
How wide are the GSM channels? |
200 kHz |
What type of radar is used for speed measurements such as the one used by the police or the police radar? |
CW Doppler radar |
With what type of emission does this tuning by 200Hz materially degrade the received signal? |
J3E |
Why does a high Q circuit discriminate against harmonics? |
Because of purer sine wave AC |
What will you change in order that gain of transistor amplifier can vary? |
The collector current |
What are 2 function of a buffer amplifier? |
Amplify and isolate |
How much of the emission must be within the bandwidth of the transmitter |
99% |
What type of 2nd detector is used for SSB and CW |
Heterodyne |
In FM broadcasting, what is the lowest used modulating frequency? |
26Hz |
What is the emission designation for VHF FM? |
F3E |
Why does a higher impedance line have lower copper loss than a lower impedance line? |
Because higher impedance line has lower current for a given power level |
What is considered as the simplest transmitter keyed on and off to produce CW Morse code? |
The oscillator |
Occasionally rockets will contain more than one satellite, what do you call the main satellite to be launched? |
Initial payload |
What are the 2 basic types of radar? |
Pulse and CW |
How many orbital plans which are equally spaced around the equator in GPS operational constellation? |
6 |
What is the popular fiber optics cable with the glass core and plastic cladding called? |
PCS (plastic clad silica) |
What is a FM receiver that causes a stronger signal to dominate the weaker signal in the same frequency? |
Capture effect |
What is the advantage of using SSB suppressed carrier AM as the modulation scheme for FDM telephony? |
It has the least bandwidth |
What may cause ionic disturbance characterized by rapid cluttering sound hence voice communication is poor? |
Aurora borealis |
What is used to convert the scene or object nearest to view the electrical signal which can be used to modulate the carrier? |
Television camera |
What is the advantage of toroid inductors over air core inductors? |
High permeability of the core |
The mandatory 24 ship-to-shore communications from 1910-1912 was established by the US, Great Britain and other maritime nation as the direct result of the sinking of the 2 famous ships, which are? |
The Republic and The Titanic |
How much is the filling fee for application of MDSCP or MPDP |
Php180 |
The frequency tolerance of FM broadcast stations is _____ above or below the assigned frequency? |
2000Hz |
What layer of the OSI model handles the transmission of bites over a communications channel? |
Physical layer |
What is the next to higher level of the multi-level activities of communications which defines how the initial data is sent and transformed into the symbols that represent it before being actually transmitted with this specific signal value? |
Coding |
Which of the ff. coaxial cable connectors is called the UHF connector? |
PL 259 |
What satellite subsystem monitors on board conditions such as temperature and battery voltage and transmits this data back to a ground station for analysis? |
TTC |
What expresses the steepness of the skirts of the skirts selectivity of a radio receiver? |
Shape factor |
In SSB, the transmitter output is expressed in terms of _________? |
Peak envelop power |
Which of the ff. is the policy guidelines to govern the operation of cable TV in the Philippines? |
PO 436 |
What is the standard signal format of a numeric paging receiver? |
NEC B3 standard |
What is the critical capacitance variation of most varactors used in frequency modulators? |
12 to 1 |
Helical antennas are often used for satellite tracking VHF because of? |
Faraday’s effect |
What traffic model is based on the assumption that calls not immediately satisfied at the first attempt are held in the system until satisfied? |
Erlang C |
What does ICT mean? |
Information and Communication Technology |
What is the typical noise figure of metals, semiconductors, FET or MOSFET used at microwave frequency? |
2 dB or less |
What is the 3rd layer of the OSI protocol model which sets up the path to transmit data between terminals and modulation is used? |
Baseband |
What system specification for 3G wireless system uses as a wide rf channel efficient coding and multiple channels to provide for both low speed circuit and high speed packet services? |
WCDMA |
If the antenna current increases 3.3 times how much is the field strength increase? |
3.3 times |
What is the term used to describe a computer operating system allows multiple program to run simultaneously without interfering with each other |
Multi-tasking |
What is the 1st type of modulation using an SB microphone called? |
Absorption or loop |
What are used to allow fiber optics to operate at much higher data rates and over longer distances with the use of range and resist abrasion? |
Polyethylene |
If the satellite is lunched at the speed exceeding 25000mph, the satellite will not go in orbit and will break away from the gravitational pull of the earth and go out in deep space what do you call this satellite? |
Space probe |
What is used to improve the signal to noise ratio for either PCM or delta modulation signals? |
Companding |
In a system, if the system to have a net gain there would be a possibility of oscillation due to feedback from this reflection, what is this called? |
Singing |
What is the voltage of the local loop on hook? |
48 Vdc |
In a propagation medium such in the glass of an optical fiber ____ is the scattering of an electromagnetic wave by particles with the size about equal or greater than the wavelength? |
MIE scattering |
What is the ratio of speed of light in air to the speed of light in another medium? |
Index of refraction |
What LED is usual signal source for plastic fiber? |
Red LED |
Why is pulse code modulation preferred over PAM? |
Because of its superior noise immunity |
What carrier shift results with insufficient grid excitation to a grid modulated stage? |
Positive |
Why are printed circuit board such as stripline and microstrip implemented on transmission lines? |
To create resonance circuits and filters |
In satellite communication system, _______ is the satellite component that senses the time or the incidence angle of solar radiation and provides electrical signal that may be used to compute the satellite orientation? |
Sun sensor |
A few centimeters long solid insulated hook-up wire that provides small capacitance to the ground that is adjusted during circuit alignment by bending slightly in one direction or another, what do you call this wire? |
Gimmick |
What is the acronym GMDSS stand for? |
Global maritime distress and safety system |
What is the main disadvantage of fiber optic cable made of glass? |
Brittleness |
In TV system, the color level control is in the ______? |
BPA |
The max. radiation for electronic equipment must not exceed ___ mr/week |
100 |
What refers to any sonic, infrasonic, or ultrasonic wave which is emitted from electronic product as a result of the operation of its electronic circuit |
Radiation |
What is the formula for REM? |
Rbe x rad |
Radiation exposure rates produced by a TV receiver shall not exceed ____ milli roentgens per hour at the distance of 5cm from any point on external surface of the receiver? |
0.5 |
Why larger antennas are receive stronger signals than smaller antenna? |
Because they have greater effective area or greater proportion of radiated energy intercepted |
What is the advantage of Dougherty linear? |
High efficiency |
What vacuum tube is used for microwave amplification and oscillation? |
Klystron |
What is the advantage of using variable and balance T-type attenuator pass as gain control? |
Maintain small constant z |
What refers to the sampling of analog signal used in a sample and hold circuit such that the sample will have the same amplitude for its whole duration |
Flat top sampling |
Which of the ff. identifies the maximum transmitted power level of a mobile phone? |
Station class mark |
Which of the ff. is not a supervisory tone? |
4000 Hz |
If the distance between the sound source and the listener is changing, the freq. heard will defer from the freq. emitted, this phenomenon is called? |
Doppler effect |
One document required for application of MPDP is a list of stock of spare parts and accessories sufficient enough to cover the warranty of mobile phone units for at least how many months? |
6 months |
How much is the inspection fee for application of MPDP or MPCP? |
Php720/year |
Which NTC memorandum circular provides for the additional rules and regulations on the purchase, sale, lease and retail of mobile phones? |
MC 08-08-2004 |
What protocol is used in the check sum method of error detection? |
X modem |
In cellular system, typically how many cells in the freq. reuse plan format? |
7 |
Complete List of Communications Engineering Coaching Materials
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