ELECTRONICS SYSTEM & TECHNOLOGIES **Biomedical Technology** 1. A mammography service examined 327 patients

during the third calendar quarter of 1996. 719 films were exposed during this period, eight of which were repeats. What is the repeat rate? a. 45.5% b. code 2.45% c. 1.1% d. 54.52% ANS. 1.1%

2. A type of luminescence where the visible light is emitted only during the stimulation of the phosphor. a. fluorescence b. phosphorescence c. after glow d. any of the above ANS. Fluorescence

3. If a heart measures 12.5 cm from side to side at its widest point, and its image on chest radiograph measures 14.7 cm, what is the magnification factor? a. 0.85 b. 1.18 c. 0.15 d. 2.2 ANS. 1.18

MF= (image size)/(object size) MF= (14.7 cm)/(12.5 cm) MF= 1.18

4. Radiation doses in the range of approximately200 to 1000 rad produce the a. Gastrointestinal (GI) syndrome b. Central Nervous System (CNS) syndrome c. Hematologic syndrome d. Prodomal syndrome ANS. Hematologic syndrome

5. Ratio of incident to transmitted radiation through a grid ratio of patient dose with and without grid a. Bucky factor b. Damadian factor c. Grid ratio d. Roentgen equivalent ANS. Bucky factor

6. A radiographic single-phase unit installed in a private office has a maximum capacity of 100 milliseconds of 120kVp and 500mA. What is the power rating? a. 42 kW b. 60 kW c. 600W d. 24kW ANS 42 Kw

Power rating=(0.7)x (mA x kVp)/1000 Power rating=(0.7)x ((500)(120))/1000

Power rating=42 kW

7. Who completes the development of first computed tomographic (CT) scanner (EMI, Ltd.) in 1973? a. Mistretta b. Forssmann c. Kuhl d. Hounsfield ANS. Hounsfield

8. It is the study of the response of an image receptor to x-rays a. sensitometry b. xeroradiography c. xeroradiometry d. spectrometry ANS. Sensitometry

9. Ratio of radiographic contrast with a grid to that without a grid a. grid ratio b. contrast improvement factor c. Collidge factor d. Bucky factor ANS. contrast improvement factor

10. Analysis of persons irradiated therapeutically with

superficial x-rays has shown that the skin erythema dose required to affect 50% of persons so irradiated is about a. 200 rad b. 400 rad c. 600 rad d. 800 rad ANS. 600 rad

11. ECG recording requires a bandwidth of 0.05 to ___Hz

a. 1000 b. 540 c. 100 d. 40 ANS.100

12. Find the potential generated if blood flowing in a

vessel with radius 0.9 cm cuts a magnetic field of 250 G. Assume a volume flow rate of 175 cubic cm per second. a. 206 uV b. 309 uV c. 903 uV d. 260 uV ANS. 309 uV

E= QB/50a E= ((175 cc.s)(250 G))/(50(0.9cm)) E= 309 uV

13. Period during which heart contracts. a. Diastole b. Systole c. block mode d. Synapse ANS. Systole

14. Apparatus for measuring blood pressure

a. defibrillator b. electrocardiogram c. plethysmograph d. sphygmomanometer ANS d. sphygmomanometer

15. Given the energy level of 6.624x10^-18 J imparted to an electron stream by an X-ray device, calculate the frequency in MHz. a. 10^6 MHz b. 45.29 MHz c. 10^10 MHz d. 300 MHz ANS. 10^10 MHz

f= E/h

f= (6.624x10^(-18) J)/(6.624x10^(-34) J-s) f= 10^10 MHz

16. It was first noted by Heinrich Hertz in 1887 and won

Albert Einstein the Nobel Prize in 1905. It refers to the emission of electrons from a clean metallic surface (phototube) when electromagnetic radiation (light waves or X-rays) falls onto that surface. a. Photoelectric effect b. Compton effect c. Bremsstrahlung d. Mie effect ANS. Photoelectric effect

17. Unit of radiation exposure or amount of X-ray

radiation that will produce 2.08x10^9 ion pairs per cubic centimetre of air at standard temperature and pressure (STP). a. Curie b. Roentgen c. Radiation absorbed dose (rad) d. Gray ANS. Roentgen

18. An optical electronic device that measures the color

concentration of a substance in solution. a. colorimeter b. flame photometer c. spectrophotometer d. chromatograph ANS.colorimeter

19. Recording of heart sounds

a. ultracardiography b. cardioacoustics c. electrocardiogram d. phonocardiography ANS. Phonocardiography

20. Recorder for measuring galvanic skin resistance

a. electrodermograph b. electromyograph c. electrocorporealograph d. electrogalvanograph ANS.electrodermograph

**Digital and Data Communications**

1. It consists of 36 unique codes representing the 10 digits and 26 uppercase letters a. Discrete code b. code 39 c. continuous code d. 20 code ANS.code 39

2. The first fixed- length character code developed for

machines rather than for people a. ASCII Code b. Gray Code c. EBCDIC code d. Baudot Code ANS.Baudot Code

3. The early pioneer in the development of error-

detection and correction procedures: a. Richard W. Hamming b. William R. Hamming c.

Emile Baudot d. Samuel Baudot ANS. Richard W. Hamming

4. The most reliable convolutional coding scheme for

error detection a. checksum b. LRC c. CRC d. VRC ANS.CRC

5. For the given parameters, determine the energy per

bit-to noise power density ratio C = 10e-12 W fb = 60 kbps N = 1.2 x 10e-14`W B = 120 kHz

a. 16.2 dB b. 14.2 dB c. 20.2 dB d. 22.2 dB ANS.22.2 dB

;

6. A signal at the input to a mu-law compressor is

positive with its voltage one-half the maximum value. What proportion of the maximum output voltage is produced? a. 0.786Vmax b. 0.876Vmax c. 0.867Vmax d. 0.678Vmax ANS.0.876Vmax

7. Inaccuracies caused by the representation of a

continuously varying quantity as one of a number of discrete values. a. alias signal b. slope overload c. distortion d. quantizing errors ANS.quantizing errors

8. Circuit for digitizing voice at a low data rate by using

knowledge of the way in which voice sounds are produced: a. vocoder b. codec c. sample-and-hold circuit d. ADC ANS.vocoder

9. A coding scheme that records the change in signal

level since the precious sample a. unipolar code b. PPM c. PCM d. delta modulation ANS.delta modulation

10. Distortion created by using too low a sampling rate

when coding an analog signal for digital transmission a. aliasing b. foldover distortion c. either a or b d. neither a nor b ANS.either a or b

11. A network with bandwidth of 10 Mbps can pass only

an average of 12000 frames per minute with each frame carrying an average of 10000 bits. What is the throughput of this network? a. 1 Mbps b. 2 Mbps c. 3 Mbps d. 4 Mbps ANS.2 Mbps

Throughput= (12 000 x 10 000)/60 = 2 Mbps 12. A telephone subscriber line must have an SNRdB

above 40. What is the minimum number of bits? a. 3.56 b. 5.63 c. 6.35 d. 3.65 ANS6.35

SNRdB = 6.02nb + 1.76 = 40 n = 6.35

13. The thick coaxial cable implementation of standard

Ethernet a. 1000 Base-T b. 10 Base-T c. 10 Base 2 d. 10 Base 5 ANS.10 Base 5

14. A bit pattern or a character added to the beginning

and the end of a frame to separate the frames a. Flag b. Firewall c. Frameguard d. Footprint ANS.Flag

15. An IPv4 has an address space of how many?

a. 4294967296 b. 6927694924 c. 2449692769 d. 9672969442 ANS. 4294967296

232 = 4294967296 16. What is the bit rate of STS 1?

a. 51.84 Mbps b. 64 kbps c. 100 Mbps d. 2.4 GHz ANS.51.84 Mbps

17. A block coding technique in which four bits are

encoded into a five bit code a. Baudot b. 2B1Q Encoding c. 4B/5B Encoding d. 4A/5A Encoding ANS.4B/5B Encoding

18. A national standards organization that defines

standards in the United States a. ANSI b. FCC c. ITU d. CCITT ANS.ANSI

19. In asynchronous transmission, one or more bits to indicate the end of transmission a. trailer b. flag c. escape byte d. stop bit ANS.stop bit

20. What is the overhead (number of extra bits) in the DS-

3 service? a. 1.368 Mbps b. 1.480 Mbps c. 2.048 Mbps d. 6.024 Mbps ANS.1.368 Mbps

**Electronics/Communications**

1. The minimum sampling rate according to Nyquist Theorem a. equal to the lowest frequency of a signal b. equal to the highest frequency of a signal c. twice the bandwidth of a signal d. twice the highest frequency of a signal ANS.twice the highest frequency of a signal

2. It is used in wireless applications in which stations

must be able to share the medium without

interception by an eavesdropper and without being subject to jamming from a malicious intruder a. modulation b. Multiple access c. multiple access d. Spread spectrum ANS.spread spectrum

3. An error detection method which uses ones

complement arithmetic a. Checksum b. CRC c. Simple-parity check d. Two-dimensional parity check ANS.Checksum

4. It is a connecting device between two internetworks

that use different models a. Bridge b. Gateway c. Repeater d. router ANS.gateway

5. It is an undesired shift or width change in digital bits of

data due to circuitry action which causes bits to arrive at different times a. alias b. impulse c. jitter d. parity ANS.jitter

6. In PCM system, it is the ratio of the maximum input

voltage level to the smallest voltage level that can be quantized a. Dynamic range b. Figure of merit c. Quality factor d. Noise figure ANS.Dynamic range

7. A multiplexer combines four 100-kbps channels using

a time slot of 2 bits, determine the frame duration.

a. 20s

b. 50s

c. 100s

d. 400s

ANS.20s 8. Determine the Hamming distance for the codewords (

10101, 11001) a. one b. two c. three

d. five ANS. Two 10101 XOR 11001 = 01100 ( presence of two 1)

9. An address space is the total number of addresses

used by the protocol, such as IPv4 and IPv6. What is the address space of IPv6? a. 232 b. 264 c. 296 d. 2128 ANS.2128

10. It is a standard designed by ITU to allow telephones

in the public telephone network to talk to computers/terminals connected to the internet

a. H. 111 b. H.123 c. H.321 d. H. 323 ANS.323

11. A computer monitor has a resolution of 1200 by 1000

pixels. If each pixel uses 1024 colors, how many bits are needed to send the complete contents of a screen? a. 12 Gigabits b. 1. 2 Gigabits c. 120 Megabits d. 12 Megabits ANS.12 Megabits

1,200 times 1000 pixels x 10 bits = 12 Mb 1024 colors requires 10 bits , 210 = 1024

**Laws and Ethics, Analog and Digital Electronics, Microelectronics, Power Line Communications** 1. The sensitivity of a radio receiver is given in terms of

dBm. If the receiver is receiving 200 mW, what is the corresponding dBm of this signal? a. 46dBm b. -46 dBm c. 23 dBm d. -23 dBm ANS.23 dBm dBm for 200 mW = 10 log (200mW/1mW) = 23 dBm

2. An antenna with a noise temperature of 75 Kelvin is

connected to a receiver input with a noise temperature of 300 K. Given the reference temperature T0 = 290 K, find the noise figure of the system. a. 0.97 dB b. 3.6 dB c. 6.02 dB d. 7.2 dB

ANS. 3.6 dB The total noise temperature of the antenna and receiver is NTtot = 75+ 300 = 375. The noise temperature is given by: where: NT noise temp, NR = Noise ratio Rearranging the above to find NR gives: NR = (375/290) +1 = 2.29 The Noise figure is the decibel equivalent of the noise ratio, such that: NF = 10 log NR = 3.6 dB

3. The modulation index of an AM radio station is 0.75. If

the carrier power is 500W, what is the total transmitted power? a. 391 W b. 438 W c. 641 W d. 688 W ANS.641 W

4. An FM transmitter system is using a 1MHz crystal

oscillator to generate a very stable 108MHz final carrier frequency. The output of the crystal oscillator is fed to a x36 multiplier circuit then mixed with a 34.5 MHz signal. The sum output of the mixer is filtered out, while the difference is fed to another multiplier in order to generate the final carrier frequency. What is the multiplier value? a. 108 b. 3 c. 1.5 d. 72 ANS. 72

Basic Block Diagram of the FM carrier generator: 1 MHz carrier > x 36 > Mixer > Multiplier > 108MHz carrier First Multiplier output: 1MHz x 36 = 36 MHz Mixer output: 36MHz + 34.5 MHz = 70.5MHz (filtered output) 36MHz 34.5 MHz = 1.5 MHz (difference fed to the next multiplier) Multiplier stage: Output = 108MHz Output = 1.5MHz x n N = 108/1.5 = 72

**Electronic Communications** 1. A/an _______ is a range of frequency in which the

upper frequency is double the lower frequency. a. bandwidth b. frequency doubler c. octave d. harmonics

ANS.octave 2. Determine the worst-case output S/N for a

narrowband FM receiver with deviation maximum of 10 kHz and a maximum intelligence frequency of 3 kHz. The S/N input is 3:1. a. 10 b. 12 c. 14 d. 16 ANS. 10

3. A small variable capacitance in parallel with each

section of ganged capacitor is called _______. a. trimmer b. converter c. padder d. autodyne ANS. trimmer

**EST** 1. How many wavelengths long are required for a pair of

conductors to be considered as a transmission line? a. b. c. 1/10 d. 5/8 ANS.1/10

2. Determine the time taken for a signal to travel down a

10 m transmission line, if its velocity factor is 0.7. a. 23.33 ns b. 14.52ns c. 76.8 s d. 47.6 ns ANS. 47.6 ns

T= L/ (Vf x Vc) T= 10 m/ (0.7)(3x108 m/s) T= 47.6 ns

3. The maximum voltage standing wave of an RG-11/U

foam coaxial cable is 52 V and its minimum voltage is 17 V. How many percent of the incident power is the reflected power? a. 51% b. 26% c. 3% d. 97% ANS.26% 2 = Pr/Pi = SWR-1 ; SWR = Vmax/ Vmin = 52/17 = 3.05 SWR+1 = 3.05 1 = 0.51 3.05 +1 Thus : 2 = (0.51)2 = 0.26 The reflected power is 26 % of the incident power

: 4. At exactly one-quarter wavelength, the short-circuited

transmission line behaves as a(an) ___________ circuit.

a. inductive b. capacitive c. parallel-resonant d. series-resonant

ANS.parallel-resonant 5. Determine the phase-shift represented by a 75 ns

delay of a 4 MHz signal to a 75-ft cable with a dielectric constant of 2.3. a. 108 degrees b. 4.8 degrees c. 52 degrees d. 250 degrees ANS.108 degrees

= 360 td / T T =1/f = 1 / 4MHz = 250 ns = 360 (75) / 250 = 108 degrees

6. Which of the following is a flat conductor separated by

an insulating dielectric from a large ground plane that is usually one-quarter or one-half wavelength long? a. stripline b. microstrip c. twin-lead wire d. shielded-pair ANS. microstrip

7. One complete revolution around a Smith Chart

represents _________ wavelengths. a. b. c. 1 d. 2 ANS.

8. A mismatched transmission line is also referred to as

a ___________ line. a. lossy b. lossless c. non-resonant d. resonant ANS.resonant

. 9. It is the ratio of the speed of propagation on a line to

that of light in free-space. a. velocity factor b. refractive index c. dielectric constant d. standing-wave ratio ANS.velocity factor

10. Which of the following is the most widely used UTP

cable that can carry baseband data at rates up to 100 Mbps at a range up to 100m? a. CAT 4 b. CAT 5 c. CAT 5e d. CAT 6 ANS.CAT 5

11. The modulated peak value of a signal is 125V and the

unmodulated carrier value is 85V. What is the modulation index? a.0.47 b. 1.47 c. 0.68 d. 0.32 ANS.0.47

m = Em/ Ec Emax = Ec + Em ; Em = Emax Ec = 125 85 = 40 V m = 40V/ 85V = 0.47 12. The total transmitted power of an AM broadcast

transmitter with a carrier power of 50kW when modulated 80 percent is: a. 62.5kW b. 66W c. 66kW d. 40kW ANS.66kW

Pt = Pc ( 1 + m2/2) Pt = 50,000 ( 1 + 0.82 /2) Pt = 66,000 W Pt = 66kW

13. One of the advantages of DSB is the savings of great

deal of power. Which of the following is the reason why it is not widely used? a. the signal occupies a narrow bandwidth b. the signal has a low S/N c. the signal is weak at high frequencies d. the signal is difficult to demodulate ANS.The signal is difficult to demodulate

14. If the input in a transmitter is collector-modulated, the

system is called a _______________________. a. low level modulator b. high-level modulator c. differential- amplifier modulator d. lattice modulator ANS.high-level modulator 15. input to an FM receiver has a S/N of 2.8. What is the

frequency deviation caused by the noise if the modulating frequency is 1.5KHz and the permitted deviation is 4KHz? a. 1,460.8 Hz b. 547.8 Hz c. 2.67 Hz d. 4,107.3 Hz ANS.547.8 Hz

-1 N/S = sin -1 1/2.8 = 0.3652

16. What circuit is used to return the frequency response

of a signal to its normal, flat level? a. pre-emphasis b. de-emphasis c. carrier-recovery d. frequency-multiplier ANS. de-emphasis

17. It is the most common means of overcoming the

problems of quantizing error and noise.

a. multiplexing b. companding c. amplifying d. anti-aliasing ANS. companding

18. ________________ means that the characteristics and performance of an antenna are the same whether the antenna is radiating or intercepting an electromagnetic signal.

a. antenna reciprocity b. antenna polarization c. antenna grounding d. tower sway ANS. antenna reciprocity 19. Which of the following methods is used to lower the

resonant frequency of a shortened vertical antenna? a. loading coil b. top hat loading c. drooping radials d. grounding ANS.top hat loading

20. Calculate the gain (relative to an isotropic) of a parabolic antenna that has a diameter of 3 m, an efficiency of 60% and operates at a frequency of 4 GHz. a. 39.8 dBi b. 41.94 dBi c. 37.66dBi d. 79.53 dBi ANS. 39.8 dBi G = 2 D2/ 2 = 3x108/ 4MHz = 0.075 m

0.0752 G= 9474.8 G = 10 log 9474.8 G = 39.8 dBi

21. It is a phenomenon caused by any support insulators used at the ends of the wire antenna. a. skin effect b. end effect c. faraday effect d. miller effect ANS.end effect

**Electronics System & Technologies** 1. A dipole antenna has a radiation resistance of 67

ohms and a loss resistance of 5 ohms, measured at the feedpoint. Calculate the efficiency. a. 90% b. 91% c. 92% d. 93% ANS. 93%

Efficiency = Rr / Rt = 67 / (67 + 5) = 93% 2. Two antennas have gains of 5.3 dBi and 4.5 dBd,

respectively. Which has a greater gain? a. The first antenna has a higher gain.

b. The second antenna has a higher gain. c. Both antennas have the same gain d. Cannot be determined ANS. The second antenna has a higher gain.\

3. A half-wave dipole is sometimes called: a. Marconi antenna b. Yagi antenna c. Hertz antenna d. none of the choices ANS. Hertz antenna

4. An antenna's beamwidth is measured

a. from +90 to 90 b. between half-power points c. from front to back d. between the minor side-lobes ANS. between half-power points

5. "Ground Effects" refers to the effects on an antenna's

radiation pattern caused by a. radio signals reflecting off the ground b. buildings and other structures on the ground c. fading d. faulty connection of the feed cable ground ANS. radio signals reflecting off the ground

6. An antenna can be matched to a feed line using

a. a shorted stub b. an LC network c. a loading coil d. all of the choices ANS. all of the choices

7. As the length of a "long-wire" antenna is increased

a. the number of lobes increases b. efficiency decreases c. the number of nodes decreases d. none of the above ANS. . the number of lobes increases

8. LPDA stands for

a. Low-Power Dipole Array b. Log-Periodic Dipole Array c. Low-Power Directed Array d. Log Power Dipole Array ANS. Log-Periodic Dipole Array

9. Field strength at a distance from an antenna is

measured with a. a slotted line b. an EIRP meter c. a dipole

d. a field-strength meter ANS. a field-strength meter

10. A receiving antenna with a built-in preamplifier

a. active antenna b. passive antenna c. coil d. LC antenna ANS. active antenna

11. Which of the following is not a reason why most half-

wave antennas are mounted horizontally at low frequencies? a. physical construction is easier b. more cost-effective c. mounting is easier d. support is easier ANS. more cost-effective

12. The shape of the electromagnetic energy radiated

from or received by an antenna is called the a. signal shape b. electromagnetic pattern c. radiation pattern d. antenna pattern ANS. radiation pattern

13. Antennas that transmit an equal amount of energy in

the horizontal direction are called a. bi-directional b. unidirectional c. omnidirectional d. unilateral ANS. omnidirectional

14. The ability of an antenna to send or receive signals

over a narrow horizontal directional range is referred to as a. focal factor b. permittivity c. directivity d. horizontal range ANS. directivity

15. A basic antenna connected to a transmission line plus

one or more additional conductors that are not connected to the transmission line form a a. parasitic array b. bi-directional array c. half-wave dipole d. counterpoise ANS. parasitic array

16. An antenna made up of a driven element and one or

more parasitic elements is generally referred to as a a. Hertz antenna b. Marconi antenna c. collinear antenna d. Yagi antenna ANS. Yagi antenna

17. Which antennas usually consist of two or more half-

wave dipoles mounted end to end? a. Hertz b. Marconi c. collinear d. Yagi ANS. collinear

18. A stacked collinear antenna consisting of half-wave

dipoles spaced from one another by one-half wavelengths is the a. broadside array b. end-fire array c. wide-bandwidth array d. parasitic array ANS. broadside array

19. When the characteristic impedance of the

transmission line matches the output impedance of the transmitter and the impedance of the antenna itself, a. the SWR will be 10:1 b. the SWR will be 1:10 c. minimum power transfer will take place d. maximum power transfer will take place ANS. maximum power transfer will take place

20. A one-quarter wavelength of coaxial or balanced

transmission line of a specific impedance connected between a load and a source in order to match impedances is a. a balun b. an autotransformer c. a Q section d. dummy load ANS. a Q section

21. By how much should two antennas be separated for

space diversity in the 11 GHz band? a. 5.5 m b. 7.5m c. 9.5m d. 11.5m ANS.5.5 m

22. What is the phase velocity of a rectangular waveguide with a wall separation of 3 cm and a desired frequency of operation of 6 GHz?

a. 3.45 x 108 m/s b. 4.35 x 108 m/s c. 4.53 x 108 m/s d. 5.43 x 108 m/s ANS.5.43 x 108 m/s 23. A transmitter and a receiver is 45 km apart. Suppose

that there is an obstacle midway between the transmitter and receiver. By how much must the path between the towers clear the obstacle in order to avoid diffraction at a frequency of 11 GHz? a. 17.52 m b. 10.51 m c. 8.76 m d. 7.52 m ANS. 10.51 m

24. How far from the transmitter could a signal be

received if the transmitting and receiving antennas where 40 m and 20 m, respectively, above level terrain? a. 44.5 km b. 45.4 km c. 54.4 km d. None of the choices ANS.44.5 km

25. A signal propagated in a waveguide has a full wave of

electric intensity change between two further walls, and no component of the electric field in the direction of propagation. The mode is a. TE11 b. TE10 c. TM22 d. TE20 ANS. TE20

26. An isolator has a forward loss of 0.7 dB and a return

loss of 26 dB. A source provides 1 W to the isolator, and the load is resistive with an SWR of 3. How much power is dissipated in the load? a. 1 W b. 851 mW c. 750 mW d. 638 mW ANS.638 mW

27. An isolator has a forward loss of 0.7 dB and a return

loss of 26 dB. A source provides 1 W to the isolator, and the load is resistive with an SWR of 3. How much power returns to the source? a. 250 mW b. 350 W c. 535 W d. 690 W ANS. 5.43 x 108 m/s

28. It is a microwave device that allows RF energy to pass through in one direction with very little loss, but absorbs RF power in the opposite direction. a. multiplexer b. circulator c. isolator d. wave trap ANS.isolator

29. A metal wrapped around the parabolic antenna aperture to eliminate sidelobes interfering nearby stations is called a. radome b. shield c. shroud d. bass drum ANS.shroud

30. The wavelength of a wave in a waveguide _________. a. is greater than in free space b. depends only on the waveguide dimensions and the free space wavelength c. is inversely proportional to the phase velocity d. is directly proportional to the group velocity ANSWER:is greater than in free space

31. Geostationary satellites are located at ____ with

respect to the equator. a. 00 longitude b. 00 latitude c. 450 longitude d. 900 latitude ANS. 00 latitude

32. The quality of a space-link is measured in terms of the

______ ratio. a. S/N b. G/T c. C/N d. EIRP ANS. G/T

33. Why does the downlink frequency appear to vary by

several kHz during a low earth orbit satellite pass? a. The distance between the satellite and ground station is changing, causing the Kepler effect b. The distance between the satellite and ground station is changing, causing the Bernoulli effect c. The distance between the satellite and ground station is changing, causing the Boyles Law effect d. The distance between the satellite and ground station is changing, causing the Doppler effect ANS. The distance between the satellite and ground station is changing, causing the Doppler effect

1. The most ambitious LEO constellation to date is

______. a. Iridium b. NAVSTAR c. Teledesic d. Globalstar ANS.Teledesic

2. A satellite-dish owner has a 3 meter dish designed for

C-band (4 GHz) operation. The owner wants to use the same dish with a new feedhorn, for Ku-band (12 GHz) satellites. What effect will the change in

frequency have on the gain and beamwidth of the antenna? a. Gain increases by 9.54 dB, beamwidth decreases to 1/3 of its former value. b. Gain decreases by 9.54 dB, beamwidth decreases to 1/3 of its former value. c. Gain increases by 9.54 dB, beamwidth increases to thrice of its former value. d. Gain decreases by 9.54 dB, beamwidth increases to thrice of its former value. ANS. Gain increases by 9.54 dB, beamwidth decreases to 1/3 of its former value.

3. The moon orbits the earth with a period of

approximately 28 days. How far away is it? Assume circular orbit. a. 380 Mm b. 382 Mm c. 384 Mm d. 386 Mm ANS.384 Mm

4. What is the length of the path to a geostationary

satellite from an Earth station if the angle of elevation is 300? a. 6400 km b. 39000 km c. 42400 km d. 46000 km ANS.39000 km

5. What is the nominal uplink frequency for the Ku

band? a. 6 GHz b. 4 GHz c. 14 GHz d. 12 GHz ANS. 14 GHz

6. To cover all inhabited regions of the earth, the

number of polar-orbit satellites required is a. 1 b. 2 c. 3 d. 5 ANS.1

**Printing** 1. The highest frequency that can be used for skywave

propagation between two specific points on earths surface. a. Critical Frequency b. MUF c. Cut-off frequency d. mid frequency ANS. Critical Frequency

2. Variation in signal loss caused by natural weather

disturbances. a. attenuation b. fading c. spreading loss d. weather loss ANS. fading

3. Determine the radio horizon for a transmit antenna that is 200 m high and a receiving antenna that is 100 m high a. 99.5km b. 96.5 km c. 95.87 km d. 97.5 km ANS. 99.

4. The height above the earths surface from which a refracted wave appears to have been reflected a. actual height b. virtual height c. average height d. mean height ANS. virtual height

5. The highest frequency that can be used for skywave

propagation between two specific points on earths surface. a. Critical Frequency b. MUF c. Cut-off frequency d. center frequency ANS. Critical Frequency

6. Electromagnetic waves that are directed above the

horizon level. a. ground waves b. surface waves c. sky waves d. space waves ANS. sky waves

**Communications / Broadcast** 1. An acoustical phenomenon wherein the sound

continues to persist after the cause of sound has stopped resulting in repeated reflections is called a. echo b. reverberation c. reflection d. diffraction ANS.reverberation

2. A group of filters has 1/3 octave of spacing. If the

initial frequency is 25 Hz, what is the next frequency available for the filter? a. 50 Hz b. 12.5 Hz c. 75 Hz d. 31.5 Hz ANS. 31.5 Hz f2 = 2x f1 where x = 1/3, fraction of an octave f2 = 21/3 x 25 = 31.5 Hz

3. + 26 dBu is how many volts?

a. 7.75 V b. 15.5 V c. 31 V d. 62 V ANS. 15.5 V

V (dBu) = 20 log [ voltage in Volts / 0.775 Volts ] 26 = 20 log [ voltage in Volts / 0.775 V ] 26 / 20 = log [ voltage in Volts / 0.775 V ] = 1.3 Voltage = log-1 (1.3) x 0.775 V Voltage = 15.5 V

4. A type of microphone that uses the principle of a capacitor as a means of transduction. It uses a polarizing voltage of between 9 and 48 V of DC supply applied to its diaphragm by an external power supply. a. Dynamic b.Condenser c. Ribbon d.Carbon ANS. Condenser

5. Determine the sound power in Watts produced by the

banks alarm if a by-stander heard the alarm at a sound pressure level of 100 dB-SPL. The by-stander is 100 ft away from the bank. a. 56.85 W b. 55.68 W c. 58.56 W d. 58.65 W ANS. 58.65 W PWL = SPL + 20 log D(m) + 8 PWL = 100 + 20 log (100/3.28) + 8 = 137.68 dB-PWL 137.68 = 10 log W + 120 W = log-1 [(137.68 120)/10] W = 58.65 Watts

6. A loudspeaker produces an SPL of 85dB-SPL at 1

meter distance and input electrical power of 1 W. How loud is the SPL at distance of 20 meters if this speaker is driven to 10 W of electrical power? a. 82 dB-SPL b. 69 dB-SPL c. 65 dB-SPL d. 79 dB-SPL ANS. 69 dB-SPL SPL@1m/1W = 85 dB-SPL (given) SPL@20m/1W = 85 - 20 log (20m/1m) = 59 dB-SPL SPL@20m/10W = 59 + 10 log (10W/1W) = 69 dB-SPL

7. A number from 0 to 1 representing the ability of a

surface material to absorb sound energy is known as a. Sound absorption c. Absorption Coefficient b. Reflection coefficient d. Room Constant ANS.Absorption Coefficient

8. The difference in dB between the loudest level of sound and the softest passage of sound is known as a. Headroom b. signal-to-noise ratio c. gain d.dynamic range ANS. dynamic range

**Satellite Communications** 1. The height above mean sea level of a satellite in a

geosynchronous orbit around Earth is: a. 35,786 miles b. 35,786 NM c. 35,786 feet d. 35,786 km ANS.35,786 km

2. The location of a satellite is generally specified in

terms of a. azimuth & elevation b. latitude & longitude c. true morth d. bearing ANS.latitude & longitude

3. A point in the orbit of an object orbiting the earth that

is located closest to Earth. a. perigee b. apogee c. apex d. subsatellite point ANS. perigee

4. Find the velocity of a satellite in a circular orbit 500

km above the earths surface. a. 76 km/s b. 76 m/s c. 7.6 km/s d. 7.6 km/s2 ANS. 7.6 km/s

Formula :

v 4x1011

d 6400

Where : v = velocity in meters per second d = distance above earths surface in km

v 4x1011

(500 6400)

= 7.6 km/s 5. Find the orbital period of a satellite in a circular orbit

36,000 km above the earths surface if the earths radius is 6400 km. a. 1440 mins b. 24 days c. 3,600 sec d. 1440 sec ANS. 1440 mins

Formula :

C

v

Where : T = orbital period C = circumference v = orbital velocity

C = 2 r

= 2 ( 6400 + 36,000 ) = 266.4 x 106 m

v 4x1011

(36,000 6400) 3.07km /s

T C

v266.4x106m

3.07x103m /s 24hrs

or 1440 minutes 6. The outline of a communications satellite antenna

pattern on the earth is known as: a. beam b. propagation pattern c. spot d. footprint ANS. footprint

7. Calculate the length of the path to a geostationary

satellite from an earth station where the angle of

satellite above earth is 36 X 103 km) a. 36,000 km b. 36,000 mi c. 39,000 km d. 39,000 mi. ANS.39,000 km

Formula :

d (r h)2 (rcos)2 rsin 8. A satellite access technique where each earth station

transmits a short burst of information during a specific time slot. a. FDMA b. DAMA c. TDMA d. SCADA ANS. TDMA ( Time Division Multiple Access)

9. An earth station antenna look angle is determined by :

a. azimuth & elevation b. longitude & latitude c. bearing d. true north ANS. azimuth & elevation

10. An ITU radiocommunication standards for satellite

services which provides information on the range of frequencies that can be used by fixed satellite service systems for emergency and disaster relief operations. a. ITU-R M1854 b. ITU-R S 009 c. ITU-R S.1001-2 d. ITU-R S.004 ANS.ITU-R S.1001-2

**Communications / Broadcast Engineering and Acoustics** 1. As per Philippine standard, frequency allocation of

AM Radio Broadcasting is from a. 535 to 1605 kHz b. 526.5 to 1605 kHz c. 535 to 1705 kHz

d. 526.5 to 1705 kHz ANS. 526.5 to 1705 kHz

2. Part of broadcasting in a day that refers to that period

of time between 1000 UTC to 2200 UTC. UTC stands for Universal Time Coordinates. a. daytime period b. nighttime period c. experimental period d. primetime period ANS. nighttime period

3. An AM broadcast service area in which groundwave

field of 1mV/m (60dBu) is not subject to objectionable interference or objectionable fading. a. primary service area b. secondary service area c. intermittent service area d. none among these ANS. primary service area

4. In antenna mast or tower construction, the required

obstruction painting and/or lighting must be imposed on mast or tower more than from the ground level. a. 100 ft b. 150 ft c. 200 ft d. 250 ft ANS. 150 ft

5. Regarding the design of AM antenna, what should be

the polarization of the radiator? a. horizontal b. vertical c. circular d. elliptical ANS. vertical

6. As per Phillipine standard, what is the minimum

frequency separation in any service area for adjacent AM radio stations? a. 40 kHz b. 200 kHz c. 36 kHz d. 300 kHz ANS. 36 kHz

7. What is the maximum power allowable for remote

pick-up stations used as broadcast auxillary services for AM and FM broadcast stations? a. 10 W b. 15 W

c. 35 W d. 200 W ANS. 35 W

8. What is the classification of an FM station having an ERP not exceeding 30kW? a. Class A b. Class B c. Class C d. Class D ANS. Class B

9. What is the modulation used for the stereophonic

subcarrier of FM composite baseband signal? a. AM DSB FC b. AM DSB SC c. AM SSB d. AM VSB ANS. AM DSB SC

10. What is the pilot subcarrier frequency used in FM

stereophonic transmission? a. 15 kHz b. 19 kHz c. 30 kHz d. 38 kHz ANS.19 kHz

11. The output power of an FM transmitter is 5 kW. If the

power loss in transmission line is around 10 W and the antenna has a power gain of 6 dB, what is the ERP of the station in kW? a. 5 kW b. 30 kW c. 20 kW d. 19.96 kW ANS. 19.96 kW GANT = 6 dB = 4 ERP = (5000 10) x 4 = 4990 x 4 = 19,960 W or 19.96 kW

12. Frequency allocation of FM broadcast in the

Philippines a. 535 1605 kHz b. 88 108 MHz c. 50 15000 Hz d. 174 216 MHz ANS. 88 108 MHz

13. What is the color TV system adopted by the

Philippines? a. NTSC b. PAL

c. SECAM d. none among choices ANS.NTSC

14. Exact value of color subcarrier frequency (MHz) is a. 3.579554 b. 3.579455 c. 3.580545 d. 3.579545 ANS. 3.579545

15. Determine the visual carrier frequency of TV channel

9 a. 175.25 MHz b. 187.25 MHz c. 193.25 MHz d. 199.25 MHz ANS.187.25 MHz fNLB = 174 + (N 7)6, using Arithmetic Progression f9LB = 174 + (9 7)6 = 174 + (2)6 = 174 + 12 = 186 MHz, low band frequency of channel 9 fVC = 186 + 1.25 = 187.25 MHz, visual carrier frequency of channel 9

16. What is the maximum allowable ERPs for channels 7

13 in Metro Manila and Metro Cebu? a. 100 kW b. 316 kW c. 350 kW d. 1 MW ANS. 1 MW

17. At NTSC standard, the number of lines per frame =

________ lines/frame a. 485 b. 525 c. 625 d. 585 ANS. 525

18. At NTSC standard, line frequency = 15734.264 Hz.

What is the equivalent line period? a. 66.556 usec b. 65.556 usec c. 63.556 usec d. 64.556 usec ANS. 63.556 usec fH = 15734.264 Hz H = 1 / fH = 1 / 15734.264 H = 63.556 x 10-6 = 63.556 usec

19. Nominal RF bandwidth of NTSC TV channel

a. 4.2 MHz

b. 4.5 MHz c. 6 MHz d. 5.35 MHz

ANS. 6 MHz 20. A land mobile station used for the transmission of TV

program materials and related communications from the scenes of events occuring at remote points from TV broadcast station studios to TV broadcast station. a. TV Pick-up station b. TV STL station c. TV Inter-city Relay station d. TV Satellite link station ANS.TV Pick-up station

21. For a total capacity of 36 Mbps and 64-QAM of digital

modulation, what is the ideal RF bandwidth? a. 4 MHz b. 5 MHz c. 6 MHz d. 7 MHz ANS. 6 MHz For a 64-QAM, the total number of symbol combinations is 64 symbols and the number of bits to produce this is n = log2 64 = 6 bits per symbol Therefore the ideal RF bandwidth is BW = fB / n = 36 Mbps / 6 bits BW = 6 MHz

22. What is the mode of radio wave propagation that

utilized ionosphere as a medium of transmission and / or reception of radio signals? a. ground wave b. sky wave c. space wave d. all of these ANS.sky wave

23. What is the wavelength of a radio signal travelling at a

frequency of 220 MHz in a coaxial line having Teflon foam as its dielectric, r = 2? a. 1.0 m b. 0.85 m c. 0.96 m d. 1.36 m ANS. 0.96 m c = 3 x 108 m/sec = 300 x 106 m/sec velocity factor vf = 1 / sqrt (r) = 1 / sqrt (2) = 0.707 = vP / c Therefore the velocity of the radio signal in the coaxial line is

vP = 0.707c = 0.707 (300 x 106) = 212,132,034.36 m/sec (or 212 x 106 m/sec approx.) so that the wavelength of the signal is = vP / f = 212 x 106 / 220 x 106 = 0.963636 m or 0.96 m approx.

24. What is the angle of refraction in a Teflon (r2 = 2)

medium of a radio wave from air (r1 = 1.0) if its angle of incidence is 45? a. 24 b. 26 c. 28 d. 30 ANS. 30

Using Snells Law Sqrt (r1) sin i = Sqrt (r2) sin r Sqrt (1) sin 45 = Sqrt (2) sin r r = sin-1 [(Sqrt (1) sin 45) / Sqrt (2)] = sin-1 (0.5) = 30 25. An ionosphere layer also termed as absorption layer

because it absorbs most of the frequencies above 100 kHz is known as the layer. a. D b. E c. F1 d. F2 ANS. D

26. As per ITU-R Recc. V.431-6 Tables 1 & 2 Wavelength

Classifications, what is the classification of Super High Frequency? a. metric b. decimetric c. centimetric d. millimetric ANS.centimetric SHF band: 3 GHz 30 GHz max = 3 x 108 / 3 x 109 = 0.1 m = 100 cm min = 3 x 108 / 30 x 109 = 0.01 m = 1 cm SHF band wavelength classification is ranging from 1 cm to 100 cm. Therefore it is centimetric wave.

27. What is a diversity scheme that uses two (2) separate antennas and receivers for each single transmitter? a. frequency diversity b. space diversity c. angle diversity d. quadrature diversity ANS.space diversity

28. What is a diversity scheme that uses two (2) different

frequencies in a simplex path? a. frequency diversity

b. space diversity c. angle diversity d. quadrature diversity

ANS. frequency diversity 29. What is the critical frequency of a layer if the

maximum value of electron density is 2 x 106 per cm3? a. 11 MHz b. 12 MHz c. 13 MHz d. 14 MHz ANS.13 MHz

Nmax = 2 x 106 per cm3 = 2 x 106 x 106 per m3 = 2 x 1012 per m3 fc = 9 x sqrt (Nmax) = 9 x sqrt (2 x 1012) fc = 12.73 MHz or 13 MHz approx. 30. A radio communication link is to be established via

the ionosphere. The maximum virtual height of the layer is 110 km. at the midpoint of the path and the critical frequency is 4 MHz. If the distance between the radio stations is 500 km, what is the suitable value for the optimum working frequency? Use flat terrain analysis. a. 8.2 MHz b. 8.3 MHz c. 8.4 MHz d. 8.5 MHz ANS. 8.4 MHz

For flat terrain analysis, tan i = d/2hv i = tan-1 [d/2hv] = tan-1 [500/2(110)] = tan-1 [2.273] = 66.25 angle of incidence MUF = fc x sec i = fc / cos i = 4 / cos 66.25 = 4 / 0.40275 = 9.932 MHz via Secant Law OWF = 0.85 x MUF = 0.85 (9.932) = 8.4422 MHz or 8.4 MHz approx. 31. The power density is inversely proportional to the

square of the distance from the source. This law is known as a. Faradays law b. Snells law c. Inverse Square law d. Gauss law ANS.Inverse Square law

32. The lowest portion of the ionosphere that is useful for

long-distance communication by amateurs; about 100 to 115 km above the earth is known as the layer. This is often termed as the Kennely-Heavyside layer. a. D

b. E c. F1 d. F2

ANS. E 33. A graph which shows the radiation in actual field

strength of electromagnetic fields at all points which are at equal distance from the antenna is known as a. Frequency Response b. Radiation Pattern c. Smith Chart d. FCC F(50,50) Graph ANS, Radiation Pattern

34. The efficiency of an antenna is 82 %. Its radiation

resistance is 30 . What is the value of its loss resistance? a. 75 b. 15 c. 12 d. 6.58 ANS.6.58 = Rd/(Rd + Rloss) 0.82 = 30/(30 + Rloss) 0.82 (30 + Rloss) = 30 = 24.6 + 0.82 Rloss Rloss = (30 24.6) / 0.82 = 6.5854 or 6.58 approx.

35. A phenomenon on the surface of the sun with

appearance and disappearance of dark irregularly shaped areas. a. SID b. 11-year sunspot c. Sporadic E-layer d. Ionospheric storms ANS.11-year sunspot

36. What should be done to increase the transmission

distance at frequencies higher than HF bands? a. increase antenna gain b. increase antenna height c. increase transmitter power d. increase receiver sensitivity ANS. increase antenna height

37. Which of the following factors must be considered in

the transmission of a surface wave to reduce attenuation? a. electrical properties of the terrain b. frequency c. antenna polarization d. all choices

ANS.all choices 38. A radio station operates at 11 meter wavelength.

What is the designated band of stations frequency? a. MF b. HF c. VHF d. UHF ANS.HF SOLUTION (IF PROBLEM SOLVING): c = 3 x 108 m/sec = 11 m = c / f f = 3 x 108 / 11 = 27 MHz approx., which is within 3 30 MHz range designated as HF band

39. What is the total radio horizon distance between an

80 ft transmitting station and a 20 ft receiving station? a. 53.66 km b. 53.66 mi c. 18.97 km d. 18.97 mi ANS. 18.97 mi SOLUTION (IF PROBLEM SOLVING): dRH (TOT) = sqrt (2 x hT) + sqrt (2 x hR) dRH (TOT) = sqrt (2 x 80) + sqrt (2 x 20) dRH (TOT) = 18.97 mi

40. A power density of 1.57 x 10-4 W/m2 is measured 50

meters from a test antenna whose directive gain is 2.15 dB. How much power was fed into the test antenna? a. 1 W b. 2 W c. 3 W d. 4 W ANS.3 W From Inverse Square Law, PD = PR/4d2 PR = PD x 4d2 = 1.57 x 10-4 x 4(50)2 = 4.93 W approx. is the radiated power GANT = log-1 [2.15 dB/10] = 1.64 PR = PFED x GANT PFED = PR / GANT = 4.93 / 1.64 = 3.007 W or 3 W approx.

**Wireline and wireless ** 1. Identical telephone numbers in different parts of a

country are distinguished by their ___. a. language digits b. area codes c. central office codes d. access digits ANS.area codes

2. Telephone traffic is measured ____

a. in erlangs c. with echo cancellers b. by the relative congestion d. in terms of the grade of service ANS.in erlangs

3. In a cellular telephone system, each cell site contains

a ____. a. touch tone processors c. repeater b. control computer d. direct link to a branch exchange ANS.repeater

4. When the signal from a mobile cellular unit drops

below a certain level, what action occurs? a. the cell site switches antennas b. the call is terminated c. the unit is handed off to a closer cell d. the MTSO increases power level ANS.the unit is handed off to a closer cell

5. In a cellular telephone system, group of cells is called

___. a. sector b. Cluster c. site d. cell segment ANS.cluster

6. In Celluar Telephone Systems, these are

transmissions from base stations to mobile units (Downlink) a. forward links b. reverse links c. TRX d. TRA ANS.forward links

7. A CDMA mobile measures the signal strength from

the base as -100 dBm. What should the mobile transmitter power be set to as a first approximation, considering - 76 dB at mobile power contol? a. 150 mW b. 200 mW c. 250 mW d. 300 mW ANS.250 mW PT = -76 dB - PR Where: PT = transmitted power in dBm PR = received power in dBm PT = -76 dB - PR = -76 dB (-100dBm) = 24 dBm = 250 mW

8. A telephone signal takes 2ms to reach its destination. Calculate the via net loss required for an acceptable amount of echo. a. 0.2 dB b. 0.4 dB c. 0.6 dB d. 0.8 dB ANS. 0.8 dB VNL = 0.2t + 0.4 dB Where:

VNL = minimum required via net loss in dB t = time delay in ms for propagation one way along line VNL = 0.2t + 0.4 dB = 0.2 X 2 + 0.4 = 0.8 dB

9. The typical voltage across a telephone when on-hook

is: a. 48 volts DC c. 90 volts DC b. 48 volts, 20 hertz AC d. 90 volts, 20 hertz AC

ANS.48 volts DC 10. Central offices are connected by:

a. local loops c. both a and b b. trunk lines d. none of the above ANS.trunk lines

11. In telephony, call blocking is:

a. cannot occur in the public telephone network b. occurs on the local loop when there is an electrical power failure c. occurs only on long-distance cables d. occurs when the central office capacity is exceeded ANS.occurs when the central office capacity is exceeded

12. The cable used for local loops in telephone system is

mainly: a. twisted-pair copper wire c. coaxial cable b. shielded twisted-pair copper wire d. fiber-optic ANS.twisted-pair copper wire

13. In DTMF, the four vertical frequencies are ____.

a. 1209Hz, 1336Hz,1477Hz,1633Hz b. 697Hz,770Hz,852Hz,941Hz c. 679Hz,770Hz, 852Hz, 941Hz d. 1208Hz,1336Hz,1747Hz,1633Hz ANS. 697Hz,770Hz,852Hz,941Hz

14. In DTMF, the Horizontal frequencies are

a. 1209Hz, 1336Hz,1477Hz,1633Hz b. 697Hz,770Hz,852Hz,941Hz c. 679Hz,770Hz, 852Hz, 941Hz d. 1208Hz,1336Hz,1747Hz,1633Hz

ANS.1209Hz, 1336Hz,1477Hz,1633Hz 15. In Celluar Telephone Systems, these are

transmissions from mobile units to base stations (Uplink) a. forward links b. reverse links c. TRX d. TRA ANS.reverse links

16. In DTMF, the horizontal frequencies is also known as

a. low group frequencies b. high group frequencies c. mid group frequencies d. top group frequencies ANS.high group frequencies

17. In DTMF, the Vertical frequencies is also known as

a. low group frequencies b. high group frequencies c. bottom group frequencies d. top group frequencies ANS.low group frequencies

18. The bandwidth of voice-grade signals on a telephone

system is restricted in order to: a. allow lines to be "conditioned" b. prevent "singing" c. allow signals to be multiplexed d. all of the above ANS. allow signals to be multiplexed

19. This is the highest-ranking office in the DDD network

in telephony in terms of the size of the geographical area served and the trunking options available. a. section center c. primary center b. regional center d. all of the above ANS.regional center

20. In Cellular Radio, AMPS stand for:

a. American Mobile Phone System b. Analog Mobile Phone Service C. Advanced Mobile Phone System d. Advanced Mobile Phone Service ANS.Advanced Mobile Phone Service

21. In Cellular Radio, BSC stands for: a. Base Station Controller c. Basic Service Contract b. Base Signal Controller d. Basic Service Code ANS.Base Station Controller 22. In Cellular Radio, MSC stands for: a. Mobile Switching Center c. Maximum Signal Carrier

b. Mobile Service Cellular d. Minimum Signal Carrier ANS.Mobile Switching Center 23. In GSM, voice channels are called:

a. traffic channels c. bearer channels b. voice channels d. talking channels ANS.traffic channels

24. In Mobile Communications, GSM uses:

a. frequency hopping c. CDMA b. direct-sequence modulation d. all of the above ANS.frequency hopping

25. In Mobile Communications, IMSI stands for::

a. Integrated Mobile Subscriber Identification b. International Mobile Subscriber Identification c. Interim Mobile Subscriber Identification d. Intermodulation System Interference ANS.International Mobile Subscriber Identification

** Electronics and Communications** 1. The most common light used in fiber-optic links is

a. Infrared b. Red c. Violet d. Ultraviolet ANS.Infrared

2. In the telecommunications industry, the most

commonly used fiber(s) are a. 50 micron b. 62.5 micron c. 50 and 62.5 micron d. 125 micron ANS. 50 and 62.5 micron

3. The abrupt change in refractive index from core to

cladding of fiber-optic cable is called the a. Total internal reflection b. Numerical aperture c. Dispersion d. Step index ANS. Step index

4. A technique that is used to minimize the pulse

dispersion effect is to a. Use a higher frequency light source b. Use plastic cladding c. Minimize the core diameter d. All the above ANS. Minimize the core diameter

5. Which is not an important characteristic of a light

detector? a. Responsitivity b. Dark current c. Power consumption d. Response speed ANS. Power consumption

6. The dispersion of light in fiber-optic cable caused by a

portion of the light energy traveling in the cladding is called a. Modal dispersion b. Material dispersion c. Waveguide dispersion d. Cable dispersion ANS. Waveguide dispersion

7. Recent laser developments for fiber-optic

communication include a. Distributed feedback (DFB) b. Vertical cavity surface emitting (VCSEL) c. Heterojunction d. Distributed feedback (DFB) and vertical cavity surface emitting (VCSEL) ANS.Distributed feedback (DFB) and vertical cavity surface emitting (VCSEL)

8. Which of the following considerations is important

when deciding between using a diode laser or an LED? a. Response time b. Power levels c. Temperature sensitivity d. Failure characteristics ANS.Response time

9. In 1815, the correct explanation of diffraction was

given by a. Maxwell b. Rayleigh c. Fresnel d. Snell ANS.Fresnel

10. It is the central part of the optical communication

system a. Light Source b. Optical Fiber c. Photodetector d. none of the above ANS.Optical Fiber

11. The light energy that is always emitted or absorbed in

discrete units a. Light Ray b. Boson c. Quanta d. Light ANS.Quanta

12. Which of the following Ethernet fiber optic standard

uses synchronous, Centralized Clock? a. 10 Base-FL (Link) b. 10 Base-FB (Backbone) c. 10 Base-FP (passive) d. Both a & c ANS.10 Base-FB (Backbone)

13. It is a mixed, multiple-service standard to allow the

transmission of voice and video over an FDDJ network.

a. FDDI - II b. FDDI - I c. Hi PPI d. Escon ANS. FDDI - II 14. It is a layer of plastic that surrounds a fiber or group of

fibers a. Buffer Tube b. Bulkhead c. Cladding d. Jacket ANS. Buffer Tube

** Signal Processing and Control Systems ** 1. The angular separation between the two half-power

points on the power density radiation pattern. a.Bandwidth b Beamwidth c. Footprint d. Azimuth ANS.Beamwidth

2. Refers to the direction in space of electric vector of

the electromagnetic wave radiated from an antenna and is parallel to the antenna itself. a.Propagation b. Coordinates c. Polarization d. Azimuth ANS.Polarization

3. Placing a metallic array on the antenna effects to

increase the current at the base of the antenna, and also to make the current distribution more uniform. What is this called? a.Reflector b. Grounding c. Top loading d. Feeding ANS.Top loading

4. What principle that states that the properties of an

antenna are independent of whether it is used for transmission or reception. a.Alternation b. Diplexer c. Reciprocity d. Repeatability ANS.Principle of reciprocity

5. Calculate the beam width between nulls of a 2-m

paraboloid reflector used at 6GHz. Note: such reflectors are often used at that frequency as antennas outside broadcast television microwave links. a.140 b. 70 c. 3.50 d. 0.8750 ANS.3.50

6. This is often used to cure the problem of great thickness required of lenses used at lower microwave frequencies or for strong curved wavefronts.

a. Splicing b. Zoning c. Curving d. Polarizing ANS.Zoning

7. A structure-generally metallic and sometimes very

complex-designed to provide an efficient coupling between space and the output of a transmitter or input to a receiver. a.Stub b. Antenna c. Transmission line d. waveguide ANS.antenna

8. The ratio comparing the power density generated by a

practical antenna in some direction, with that due to an isotopic antenna radiating the same total power. a. directivity b. Directive gain c. bandwidth d. Elementary doublet ANS.Directive gain(b)

9. Any array that is directional at right angles to the

plane of the array is said, by inference, to have __________. a.Broadside b. Broadside array c. Broadside action d. End-fire array ANS.Broadside action

10. The ratio of the focal length to the mouth diameter is

called __________ of the parabola, just as in camera lenses. a. focus b. resolution c. feed d. aperture ANS.Aperture

11. Corresponds to a resonant transmission line, and the

dipole antennas describe so far have been resonant. a. Non-resonant antenna b. Resonant antenna c. Antenna arrays d. None of the above ANS.Resonant antenna

12. An optic fiber is made of glass with a refractive index

of 1.55 and is clad with another glass with a refractive index of 1.51. Launching takes place from air. What numerical aperture does the fiber have? a. 0.852 b. 0.352 c. 1.032 d. 0.235 ANS. 0.352 By equation (20.10), the fractional difference between the indexes is: =(n1-n2)/n1 =(1.55-1.51)/1.55 =0.0258 By equation (20.11), the numerical aperture is found to be:

NA=n1(2) =1.55[(2)(0.0258)] = 0.352

13. An optic fiber is made of glass with a refractive index

of 1.55 and is clad with another glass with a refractive index of 1.51. Launching takes place from air. What is the acceptance angle? a. 22.8 b. 18.6 c. 20.6 d. 23.6 ANS. 20.6 By equation (20.10), the fractional difference between the indexes is: =(n1-n2)/n1 =(1.55-1.51)/1.55 =0.0258 By equation (20.11), the numerical aperture is found to be: NA=n1(2) =1.55[(2)(0.0258)] = 0.352 By equation (20.8), the acceptance angle is: 0(max)=sin-1NA= sin-10.352=20.6

14. For a single-mode optical cable with 0.25-dB/km loss,

determine the optical power 100km from a 0.1-mW light source. a. -25dBm b. -45dBm c. -35dBm d. -30dBm ANS. -35dBm P=0.1mW x 10-{[(0.25)(100)]/(10)} =1 x 10-4 x 10{[(0.25)(100)]/(10)] =(1 x 10-4)(1 x 10-25) =0.316W P(dBm)= 10log = -35dBm

15. For an optical fiber 10km long with a pulse-spreading

constant of 5ns/km, determine the maximum digital transmission rates for return-to-zero. a. 10Mbps b. 20 Mbps c. 50 Mbps d. 5 Mbps ANS.20Mbps

16. In fiber optics, it is a measure of the conversion

efficiency of a photodetector. It is the ratio of the output current of a photodiode to the input optical power and has the unit of amperes per watt

a. Dark current b. Responsivity c. Spectral Response d. Light Sensitivity ANS.Responsivity

17. A phenomenon also called stress corrosion resulting if the glass fiber is exposed to long periods of high humidity? a. Static fatigue b. Absorption c. Scattering loss d. Dispersion ANS. Static fatigue

18. The theory which states that when visible light or

high-frequency electromagnetic radiation illuminates a metallic surface, electrons are emitted. a. Photoelectric effect b. Plancks law c. Photoemission effect d. Ray Theory of light ANS.Plancks law

19. The science of measuring only light waves that are

visible to the human eye a. Radiometry b. Photometry c. Optometry d. Optics ANS. Photometry

20. The process of constructing an ILD that is similar to

LED except that the ends are highly polished. a.epitaxially grown b. Planar diffusion c. lasing d. None of the above ANS.Lasing

21. A phenomenon in optical fibers communication

system that is caused by the difference in the propagation times of light rays that take different paths down the fiber. a. Pulse spreading b. Wavelength distortion c. Rayleigh scattering d. Microbending ANS.Pulse spreading

Data comms 1. Is an OSI Layer which is responsible for providing error-free communications across the physical link connecting primary and secondary stations (nodes)

a.Data Link Layer b. Transport Layer c. Session Layer d. Presentation Layer

ANSWER: a. Data Link layer

2. Is the ratio of the largest possible magnitude to the smallest possible magnitude that can be decoded by the digital-to-analog converter.

a. Step size b. Quantization Error c. Resolution d. Dynamic range

ANSWER: d. Dynamic range

3. Is a PCM system which uses a single bit PCM code to achieve digital transmission of analog signals

a.Trellis Coding b. Delta modulation c. Differential PCM d. QAM

ANSWER: b. Delta modulation

4. Is a redundancy error detection scheme that uses parity to determine if a transmission error has occurred within a message and is sometimes called message parity.

a. Longitudinal redundancy check b. Vertical redundancy check c. Character Parity Check d. Checksum

ANSWER: a. Longitudinal redundancy check

5. Is an n-bit data register inside the UART that keeps track of the UARTs transmit and receive buffer registers

a. Control Register b. Status Word register

c. Control and Status Register d. Command registerANSWER: b. Status Word register

6. Is an access method used primarily with LANs configured in a bus topology.

CSMA/CD b. CSMA c. CSMA/CA d. MA

ANSWER: a. CSMA/CD

7. IP version 4 address length is

32 bits b. 24 bits c. 40 bits d. 48 bits

Ans. 32 bits

8. Is a multiport bridge that provides bridging function.

a. Repeater b. hub c. Router d. Switch ANSWER: d. Switch

9. Is a device which operates in the Network layer and it makes forwarding decisions on the basis of network addresses

a. Repeater b. hub c. Router d. Switch

ANSWER: c. Router

10. OC-1 (STS-1) line rate is

a. 51.84 Mbps b. 1.544 Mbps c. 3 Mbps d. 2.048 Mbps

ANSWER: a. 51.84 Mbps

11. Is one in which all computers share their resources with all the other computers on the network.

a. Dedicated client server network b. Peer-to-peer client/server network c. Peer-to-peer network d. All of the above

ANSWER: b. Peer-to-peer client/server network

12. Is used to interface DTEs to digital transmission channels

a. Data modem b. Router c. Splitter d. Channel service unit

ANSWER: d. Channel service unit

13. Modulation which combines encoding and modulation to reduce the

probability of error.

a. DPSK b. FSK c. QAM d. TCM

ANSWER: d. TCM

14. Is an empirical record of a systems actual bit error performance

a. ER b. BER c. EER d. BERT

ANSWER: b. BER

15. Is an error-correcting code used for correcting transmission errors in synchronous data streams.

a. Trellis Code b. EBCDIC c. Bisync Code d. Hamming code

ANSWER: d. Hamming code

RADIO WAVE 1. The electric field intensity is measured in:

a. V/m b. V-m c. C/m d. V/C

ANSWER:a. V/m

2. It is a result of an increase in the charge density in dielectric materials.

a. polarization b. dipole moment c. potential d. potential difference

ANSWER polarization

3. It refers to the maximum antenna gain

a. directivity b. directive gain c. power gain d. power density

ANSWER: a. directivity

4. The maximum horizontal distance between the transmitter and the receiver for line of sight propagation is known as:

a. radio horizon b. range c. single hop distance d. service region

ANSWER: a. radio horizon

5. Typical mode of radiation of helical antenna is:

a. end fire b. normal c. common mode d. differential mode

ANSWER: a. end fire

6.The electric field is perpendicular to the earths surface, the polarization is:

a. vertical b. normal c. horizontal d. circular

ANSWER:a. vertical

7. In what major RF band is ground wave basically applied?

a. MF b. HF c. VHF d. UHF

ANSWER a. MF (Medium Frequency)

8. A measure of mismatch in a transmission line

a. reflection coefficient b. propagation delay

c. standing wave ratio d. all of these

ANSWER:c. standing wave ratio

9. The highest frequency that can be set back to earth by the ionosphere, if wave is sent vertically upward.

a. maximum usable frequency (muf) b. propagating frequency

c. critical frequency d. cut-off frequency

ANSWER: critical frequency

10. Travel in a straight line from the transmitting antenna to the receiving antenna

a. ground wave b. scatter c. space wave d. sky wave

ANSWER:c. space wave

11. VLF waves are for some types of services because

a. of low powers required b. the transmitting antennas are of convenient size

c. they are very reliable d. they penetrate the ionosphere easily

ANSWER:c. they are very reliable

12. It is the distance between two wave fronts having the same phase at any given instant.

a. wavefront b. wavelength c. wave distance d. field intensity

ANSWER:b. wavelength

13. It is a piece of transmission line which is normally short-circuited at the far end.

a. terminator b. stub c. quarter wave transformer d. none of these

ANSWER: b. stub

14. A 50 ohms transmission line is connected to a 30 ohm resistive load. Calculate the reflection coefficient.

a. 0.35 b. 0.25 c. 0.10 d. 0.15

ANSWER: b. 0.25

SOLUTION ( IF PROBLEM -SOLVING)

Ref Coeff = (30 50)/(30 + 50) = 0.25

15. The characteristic impedance of a transmission line does not depend upon its

a. conductor spacing b. conductor diameter

c. length d. conductor radius

ANSWER: c. length

16. Characteristic impedance of a transmission line is the impedance measured at the _______ when its length is infinite.

a. input b. shorted end of the line c. output

d. midsection

ANSWER:a. input

17. Which region of the ionosphere is mainly responsible for long-distance night time communications?

a. D layer b. E layer c. A layer d. F layer

ANSWER: d. F layer

18. Which is properly terminated antenna?

a. rhombic b. dipole c. marconi d. hertz

ANSWER: a. rhombic

19. Occurs when the radio beam is at point of grazing over an obstacle.

a. diffraction b. refraction c. absorption d. reflection

ans: diffraction

20. A microwave communications system, space loss calculation formula is

a. 92.4 + 10 log F + 20 log D b. 94.2 + 10 log F + 20 log D c. 92.4 + 20 log F + 20 log Dd. 94.2 + 20 log F + 20 log D

ANSWER:

c. 92.4 + 20log F + 20 log D

DATA

1. The technique that uses the BPSK vector relationship to generate an output with logical 0s and 1s determined by comparing the phase of two successive data bits is

a. CSU/DSU b. DPSK c. TDM d. CVSD

ANSWER: b. DPSK

2. A special digital modulation technique that achieves high data rates in limited-bandwidth channels is called

a. Delta modulation b. Pulse-coded modulation (PCM) c. Quadrature amplitude modulation (QAM) d. Pulse amplitude modulation (PAM)

ANSWER: c. Quadrature amplitude modulation (QAM

3. FSK systems are much superior to two-tone amplitude-modulation systems with respect to

a. Noise performance b. Bandwidth requirements of the channel c. Ionospheric fading characteristics d. Power consumption

ANSWER: c. Ionospheric fading characteristics

4. Using an oscilloscope to display overlayed received data bits that provide information on noise, jitter, and linearity is called a

a. Eye pattern b. Constellation pattern

c. Statistical concentration d. Loopback

ANSWER:a. Eye pattern

5. The type of radio transmission that uses pseudorandomly switched transmissions is known as

a. Facsimile b. Spread spectrum c. Synthesizing d. Compression

ANSWER: b. Spread spectrum

6. The acronym CDMA refers to ________.

a. Channel-division multiple-access systems b. Carrier-division multiple-access systems c. Capture-division multiple-access systems

d. Code-division multiple-access systems

ANSWER:Code-division multiple-access systems

7. The acronym OFDM refers to ________.

a. Orthogonal Frequency Division Multiplexing

b. Over Frequency Division Multiplexing c. Optional Frequency Division Modulation d. Orthogonal Frequency Division

Modulation ANSWER: Orthogonal Frequency Division Multiplexing

8. Using radio to transmit gathered data on some particular phenomenon without human monitors is known as

a. Radio facsimile b. Radio telemetry c. Radio teletype d. Radio multiplexing

ANSWER: Radio telemetry

9. The acronym for the form of data transmission in which the modulating wave shifts the output between two predetermined frequencies is _____.

a. FSK b. PSK c. FPF d. FSA

ANSWER: a. FSK

10. Pseudorandom implies a sequence that can be _____ but has the properties of randomness.

a. decoded b. detected c. re-created d. minimized ANSWER: re-created

11. ______ implies that both analog and digital signals share the same channel bandwidth.

a. AM b. Hybrid c. FM d. RF

Ans: hybrid

12. Telemetry may be defined as _____ metering.

a. distance b. specialized c. remote d. data

ANSWER: Remote

13. Which is not a type of pulse modulation?

a. Pulse-amplitude modulation (PAM) b. Pulse-width modulation (PWM) c. Pulse-frequency modulation (PFM) d. Pulse-position modulation (PPM)

ANSWER: Pulse-frequency modulation (PFM)

14. PPM and PWM are superior to PAM systems in

a. Noise characteristics b. Bandwidth characteristics c. Simplicity in design d. Frequency response of the intelligence

signal ANSWER: Noise characteristics

15. A procedure that decides which device has permission to transmit at a given time is called

a. Line control b. Protocol c. Flow control

d. Sequence control

ANSWER: Line Control

16. The major difficulty faced by delta modulators is

a. Excessive noise producing errors b. Slope overload c. Insufficient frequency response of the

intelligence signal d. Complexity of design

ANSWER: Slope overload

17. The AT&T T1 lines

a. Use 16-bit PCM code and include 24 voice channels

b. Use delta modulation and include 48 voice channels

c. Use 8-bit PCM code and include 24 voice channels

d. Use delta modulation and include 24 voice channels

ANSWER: Use 8-bit PCM code and include 24 voice channels

18. The ground wire in a USB cable is ______

a. Yellow b. Blue c. Red d. Brown

ANSWER: Brown

19. A(n) ________ is used to allow a digital signal to be transmitted on an analog channel.

a. codec b. alias c. modem d. PSK

ANSWER: Modem

20. The bit ________ is the amount of power in a digital bit for a given amount of time.

a. error b. energy c. joule d. hp

ANSWER: energy

21. The relationship for bit rate to ________ bandwidth is defined by the Shannon-Hartley theorem.

a. modem b. codec c. channel d. amplifier

ANSWER: Channel

22. In an S/H circuit, the time that it must hold the sampled voltage is

a. Aperture time b. Acquisition time c. Flat-top time d. Dmin

ANSWER: Aperture time

23. Error signals associated with the sampling process are called

a. Foldover distortion b. Aliasing c. Nyquist rate d. Foldover distortion and aliasing

ANSWER: Fold over distortion and aliasing

24. A(n) ________ is a single LSI chip containing both the ADC and DAC circuitry

a. modem b. DSP c. codec d. ASIC

ANSWER: codec

25. The NRZ digital signal-encoding format has a ________ component in the waveform.

a. dc b. sinusoidal c. harmonic d. parity

ANSWER: dc

ReedSolomon codes utilize a technique called ________ to rearrange the data into a nonlinear ordering scheme to improve the chance of data correction

a. pseudorandom b. BSC c. interleaving

d. quantizing ANSWER: interleaving

1. .For an electronic device operating at a temperature of 17C with a bandwidth of 10 kHz, determine the thermal noise power in dBm .

a. 134dBm b. 130dBm c. -134dBm d. 130dBm

ANSWER: c. -134dBm SOLUTION (IF PROBLEM-SOLVING) N = KTB T(kelvin) = 17C + 273 = 290 K B = 1 x 104 Hz = (1.38 x 10-23)(290)(1 x 104) = 4 x 10-17 W N(dBm) = 10log (4 x 10-17) = -134 dBm 0.001 2. A 300 resistor is connected across the 300 antenna input of a television receiver. The bandwidth of the receiver is 6MHz, and the resistor is at room temperature .Find the noise voltage applied to the receiver input.

a. 5.4 V b. 3.12 V c. 4.5 V

d. 6.7 V ANSWER: a. 5.4 V SOLUTION (IF PROBLEM-SOLVING)

VN =

= 4(1.38 x 10-23 J/K)(293 K)(6 x 106 Hz)(300

) = 5.4 x 10-6 V = 5.4 V 3. The signal power at the input to an amplifier is 100W and the noise power is 1 W. At the output, the signal power is 1W and the noise power is 30mW. What is the amplifier noise figure, as a ratio? a. 3.5 b. 4.5 c. 3 d. 4 SOLUTION (IF PROBLEM-SOLVING) (S/N)p = 100W = 100 1W (S/N)o = 1W = 33.3 0.03W NF (ratio) = 100 = 3 33.5

4. It is desired to operate a receiver with NF = 8dB at S/N = 15 dB over a 200-KHz bandwidth at ambient temperature. Calculate the receivers sensitivity

a. -84dBm b. -98dBm c. -80dBm d. -75dBm

SOLUTION (IF PROBLEM-SOLVING) S = Sensitivity = -74dBm + NF + 10logf + desired S/N S = -174 + 8 + 10log(200,000) + 15 S = -98 dBm 5. A Satellite receiving system includes a dish antenna ( Teq = 35 K) connected via a coupling network (Teq= 40 K) to a microwave receiver (Teq=52 K referred to its input). What is the noise power to the receivers input over a 1-MHz frequency range?

a. 1.75 x 10-15W b. 1.75 x 10-12W c. 1.15 x 10-15W d. 1.15 x 10-12W

SOLUTION (IF PROBLEM-SOLVING) PN = KTf = 1.38 x 10-23 J/K (35 + 40 + 52)K (1MHz) = 1.75 x 10-15 W 6. Equivalent temperature of a passive system having the same noise power output of a given system.

a. Noise figure b. Total temperature c. Equivalent temperature d. Noise temperature

Answer:

d. noise temperature 7. The noise voltage produced across a 50 is input

resistance at a temperature of 302C with a bandwidth of

6 MHz is ______.

a. 5.15 V b. 3005mV c. 2124mV d. 2.24V

SOLUTION (IF PROBLEM-SOLVING

VN = = 4(1.38 x 10-23)(302)(6

x 106)(50) = 2.24V 8. Determine the worst-case output S/N for a broadcast FM program that has a maximum intelligence frequency of 5 kHz. The input S/N is 2

a. 2.5 b. 30 c. 3 d. 25

SOLUTION (IF PROBLEM-SOLVING) = x fi = 0.5 x 5 kHz = 2.5 kHz 75 kHz = 30 2.5 kHz

** Signal Processing and Control Systems**

1. Suppose that energy Q is required to accelerate a car from rest to v, neglecting friction. How much added energy would be required to increase the speed from v to 2v? a. Q b.2Q c. 3Q d.4Q

ANS. 3Q

Using the energy equation W=KE2 KE1

Q = 0.5mv2 0 - condition 1

W = 0.5m(2v)2 0.5mv2 - condition 2

W=2mv2 0.5mv2 = 3(0.5mv2) = 3Q

2. Suppose you want to store 1.00 J of electric potential energy in a volume of 1.00 m3 in vacuum. What is the magnitude of the required electric field? a. 0.475 MV/m b. 0.336MV/m c. 0.225TV/m

d. 0.113TV/m

ANS.E=0.475 MV/m

u=1.00J/1.00m3 = 1.00J/m3

E=0.475 MV/m (a)

3. Material a is a water and material b is a glass with index of refraction 1.52. If the incident ray makes an angle of 60o with the normal, find the direction of the reflected ray. a. 49.3o b. 91.3o c. 60o

d. 34.7o

ANSWER: 60o

4. The wavelength of the red light from a helium-neon sensor is 633 nm in air but 474 nm in the aqueous humor inside our eyeballs. Calculate the speed of light in this substance. a. 2.25 x 108 m/s b. 3.25 x 108 m/s

c. 3.00 x 108 m/s d. 1.25 x 108 m/s

ANS. 2.25 x 108 m/s

5. A spaceship moving away from Earth with speed of 0.900c fires a robot space probe in the same direction as its motion, with speed of 0.700c relative to the spaceship. What is the probes velocity relative to the Earth? a. 0.900c b. 0.345c c. 0.700c d. 0.982c

ANS. 0.982c

6. In optics, this effect refers to the blurring of the image produced on a concave mirror due to the convergence of rays far from the mirror to other points on the principal axis. What do you call this effect? a. spherical aberration b. focal divergence c.

parallax error d. Snells effect

ANS.spherical aberration

7. In fluid mechanics, this shows that the pressure of a fluid decreases as the speed of the fluid increases. In addition, the pressure of a fluid decreases as the elevation increases. a. Clairuts equation b. Bernoullis

equation

c. Maxwells equation d. Hyrdofluid equation

ANS.Bernoullis equation

8. In electrodynamics, what term refers to the average speed of the charge carriers? a. drag velocity b. molecular-kinetic speed

c. drift speed d. charge velocity

ANS.drift speed

9. In electromagnetics and wave theory, what refers to waves, commonly generated by electronic devices, whose wavelengths ranges from approximately 0.3m to 10-4 m. Due to their short wavelengths these are often used in radar systems and for studying the atomic and molecular properties of matter. a. Radio waves b. Microwaves

c. AM waves d. Radar waves

ANS.microwaves