Communications Engineering Coaching Materials: Section 1 Module 5

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

Communications Engineering Coaching Materials

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