Communications Engineering Coaching Materials: Section 1 Module 4

This is the Section 1 Module 4 of the compiled Communications Coaching Materials taken from different sources including but not limited to Communications books, past Board Exams Questions, Journals and the Internet.

Communications Coaching Materials: Section 1 Module 4

This is the Section 1 Module 4 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 4



What is the maximum VF tone that may be fed to a voice signal

+6 dB

What is the maximum power of the Class 1 analog mobile phone

600 mW

The average voltage value of the 3.58MHz modulated chrominance signal in TV receivers is___________

The brightness of the color

How many lines does a standard NTSC has?


F3 emission means carrier frequency is modulated by _______


The aeronautical radio navigation land station that provides direct bearing on that station from an aircraft is known as _____________

Omni-directional range station

What is the frequency tolerance for aircraft station employing SSB transmission?

20 ppm

The range of the human hearing can form how many octaves


What results in the luminance components interfering in the color signal, it occurs whenever there is diagonal detail on that picture and gets worse with motion

Cross luminance

How many horizontal lines are blanked out in the frame of TV receivers by V blanking


What would be the bandwidth of an AF filter for CW

500 to 1000 Hz

A superjumbo group has how many voice band channel


A characteristic of the modulating signal that is proportional with the amount of frequency deviation from the carrier center frequency in FM


“?” requires that the amplitude of each sample be converted into ______

Binary number

In the single tube class C amplifier why is the “?” modulated envelop that made up of varying amplitude dc pulses

Because of flywheel

What is the data transmission rate of the North American AMPS

10 kbps

The split pair is used by IBM token ring network that operates at either

4 or 16 Mbps

In acoustics, what do you call the present combination of interval

Consonant interval

What is a system where cables and wires are placed within the ceiling and poked up in the resistance floor structured to office or the room above

Poke probe

3G wireless system was introduced in what year


In telephone system, what traffic model is based on the assumption that calls are not immediately satisfied that the first attempt are held in the system until it is satisfied


What is the maximum VF tone that may be fed in the telephone line

0 VU

What type of modulation is produced by sampling an analog signal


What is the number of lines scan per frame in the raster on the picture tube


What is the velocity of the geostationary satellite in orbit

6879 statute mph

Which navigation does not have global range


What refers to the system where an aircraft’s navigation aid measures the time interval between an interrogatory pulse and the reply from the radar from a radar beacon

DME (Distance Measuring Equipment)

What is the accuracy of LORAN C long range hyperbolic radio navigation system

¼ of a mile absolute & >100ft

What is the main advantage of GPRS

It doesn’t require a connection

How many TV fields are recorded on one slant track of tape


What frequency sharing technique uses highly directional spot beam antennas to prevent interference between stations of the same frequency.

Spatial isolation

What is used to produce low power microwave oscillators

Tunnel diode

What is the variation of the discriminator which greatly reduces sensitivity to amplitude variations and causes a 50% reduction in output voltage

Radio detector

Under the revised regulation governing cable TV systems in the Philippines regular duplicated by the network programming by one or more station in a week during the hours of 6 to 11 PM local time to a total of how many hours or more?

14 hours

What is the minimum rejection of a CATV system

60 dB

In CATV system what is sound section isolation

40 dB

In CATV system what is the RF output terminal match

16 dB

In the NTSC regulation, how much is the fine for the MPSC operating without valid NTC permit


What is the term for the ratio for the luminous power to the radiant power in the sample of light and expressed in lumens per watt of gradient energy


What do you call a special microwave coaxial cable which is made of hard tubing rather that wire with an insulating cover that can be used on the lower microwave band

Hard line

Which of the following are antennas made with micro strip on PCBs

Patch antenna

Which coaxial connector is of more complex and expensive that do a better job in maintaining the electrical char of the cable through interconnection

n-type connector

What is the dielectric constant of polyethylene insulator


How is tapped single button microphone cleared?


What helps protect fiber against degradation cause by moisture


For an angle of incidence = to the critical angle the light will be refracted

Along the normal

How much more feed point Z does a folded dipole have than normal dipole

4 times

What filter may be connected between a CB transmitter and its antenna

Low pass filter

When real time communication is required the only way to address the second fragment is to use a ____ containing more that 1 satellite


What is the common usage of single button microphones

In telephones

What is the advantage of using hub over direct interconnection to all the terminals

Its easy to move computers

A broadcast station is transmitting but not modulating, what is heard in a receiver tuned to its frequency


A network using microwave for two way transmission of telephony and in high speed data

Local Multipoint Distribution System (LMDS)

In TV system, if the 3.58MHz C amp in the receiver does not operate, the result will be __________?

No color

What refers to the emphasizing low level signals and compressing high level signals


A system that allows user to access documents from widely separated sources of the internet using a common interface


What is the max efficiency of class C amp?


What is the max recommended cable length of RS232C cable?

50 feet

What is the typical value of line turn around?

1.5 ms

Which pulse in the V blanking corresponds to 3H lines wide?

V sync

What refers to the nonlinear effect that occurs at low power as low as 3mw in single mode fiber and takes the form of a light shifter slightly in frequency from the original light wave

Bruilloin scattering

In wide area networks what routing technique requires each node to take the incoming packet and retransmit it onto every outgoing line?


For analog dram scanners what type of modulation is used after the receive light has been converted into electrical energy?


What is the most commonly used transmission line?

Coax cable or line

In what 2 systems in the voice transmitter can speech processing be used?

AF and RF

What can be determined about a transformer by an ohmmeter?

Winding continuity, shorts to case and interwinding shorts

Why is a matched line indistinguishable from an infinitely long line as seen from the source?

Since no energy is reflected from the match load, so for the source it appears as if energy is put into the line continuous to move down the line forever

What type of circuit produces even order harmonics?


What is the designation of SSB with full carrier?


What is the achievable data rate of the 3G cellular system?

More than 2Mbps

What is the time period for a single time slot in GSM TDMA structure?


What packets switch data technique is used with the GSM systems?


What do you call the process by analog signal are transmitted by converting them into a series of pulses whose amplitude is approximately the shape of the analog signal


In Ethernet LAN, what situation arises when two or more terminals try to transmit in the network at the same time?


What do you call the interval which it’s an integer or whole fraction ratio

Octave interval

What is defined as the ratio of frequency of two pure tones?


What do you call the first note of the musical scale?

Root note

In what year will the FCC face the analog broadcasting?


Which of the following is or are parts of the network interface card?

Both BNC and RJ49 connectors

Which of the ff wavelengths where absorption of electromagnetic waves becomes peak due to vibrational resonance in the water vapor molecule

1.35cm and 1.7mm

What class of mobile phone has a maximum power level specified as ERP of -2dBW or 600mW

Class III (mobile phone)

What refers to a series of tones that sounds good when used in combination

Musical scale

An MPD shop properly identifies its business and location by posting conspicuously at the entrance of its premises a sign board, what are the dimensions of the sign board?

50cm x 100cm

Electronic technician as defined by the MPSCP implementing guidelines should be a graduate of an electronic technician course and should have completed a formal training course in the repairs, servicing and maintenance of mobile phones conducted by mobile phone manufacturers and or training service center duly accredited by _________


Under RA 9292, one qualification to be a member of the board is being a citizen and resident in the Philippines for at least how many years?

5 years

What technique is employed by the transmitter to avoid accidental flags

Bit stuffing

If two signal are in quadrature, what tie the phase relation

90 degrees

What do you call a type of communications by propagation is primarily by the direct or space wave which travels in straight line at frequency above 30Mhz

LOS communication

What feature of SONET allows data spin with different paths to be sync

Payload pointer

What is a specialized transformer that allows telephone voice signals to travel in both directions simultaneously in a single twisted pair loop

Hybrid coil

Cable TV companies collect signals and programs from many sources in a facility called ____________

Head end

Refers to the transmission of multiple TV signals which are frequency multiplexed on a single cable to be used in lieu of over the air signal trans

Cable TV

What is the other name of super refraction


What is the reason why tropospheric ducting not used very much in practical communication systems?

Because it is not reliable

What is the function of a hybrid in the telephone handset

Decrease mic signal in phones

When the called telephone is ringing, the CO sends a pulse AC voltage to the calling telephone. What is that signal called?

Ringback signal

What unit refers to radiation other than x-rays which will have an absorption equal to 1 roentgens

Rep - roentgen equivalent physical

Different sources of radiation have different effect which are related to x-rays by a number which is referred to as the ______

Rbe – roentgen biological effectiveness

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