est - pre board april 2007

8/13/2019 EST - Pre Board April 2007

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COMMUNICATION PRE-BOARD EXAM (April, 2007)

1. What is the call sign for AM in Mindoro?a. DXb. DZc. DCd. DW

2. What is the station spacing form AM channelallocation in the Philippines?a. 40 K!b. 36 !"c. 4" K!d. 20 K!

#. $t is the time for the densit% of the so&nd energ% todeca% in the room &p to '0 d( )elo* the original +al&e.a. transition). act&ationc. reorientation#. r$%$rb$r&'i

4. ,orm&la &sed in determining the re+er)eration time if

the a+erage a)sorption is less than 0.2.a. -orris/%ringb. *&bi$+c. tephens and (atesd. Asi)a

". What is the fre&enc% of the e&ali!ing p&lses in 3signal transmission?a. #0 "00b. 3 00c. #2 "00d. ## "00

'. he )laning p&lses are responsi)le for the fl%)acor retrace in the 3 screen. What is the hori!ontal)laning fre&enc%?a. '0 !). 1" 5"0 !c. #1 "00 !d. 1" "5" !

5. Chrominance is the #."6 M! color s&)carrier *ith&adrat&re mod&lation. What is the fre&enc% of the $ orthe inphase chrominace signal?a. 0." M!b. .3 M!"c. #."6 M!d. 4." M!

6. $t is the o+erall intensit% of ill&mination *hichdetermines the )acgro&nd le+el in the reprod&cepict&re.a. Conrastb. Bri/'$++c. h&ed. Color 7e+el

8. $t is a men& )ased program &sed to e9plore andaccess the internet reso&rcesa. telnet). access

. p/$rd. na+igator

10. 10(ase" is the thicnet coa9ial ca)le specificall%the :; 11. *hat is the t%pical diameter of this ca)le?a. 0.# inch

b. 0.1 i/c. 0." inchd. 0.' inch

11. he loss in signal po*er as light tra+els do*n afi)er is called.&. &''$&'i). propagationc. a)sorptiond. scattering

12. his theorem sets a limit on the ma9im&m capacit%of a channel *ith a gi+en noise le+el.a. artle% theoremb. */&-!&r'l$ '/$r$4

c. -%&ist theoremd. hannon theorem

1#. Which la%er of the atmosphere has relati+el% littleeffect on radio *a+es?&. *'r&'+p/$r$).ropospherec. ionosphered. )iosphere

14. What is the height of the /la%er of the ionosphere?a. #0"" milesb. l&$r -50 4il$+c.80240 milesd. 240#'0 miles

1". What are the fo&r main classes of reg&lar +ariation*hich affect the e9tent of ioni!ation in theionosphere?&. D&il, +$&+&l, -$&r, 27-#&+

%&ri&'i). Dail%< seasonal< 12%ear< and 25da%s +ariationc. Dail%< seasonal< 1#%ear< and 25da%s +ariationd. Dail%< seasonal< 14%ear< and 25da%s +ariation

1'. $n *hat la%er of the atmosphere do +irt&all% all*eather phenomena occ&r?a. tratosphereb. Trp+p/$r$

c. ionosphered. )iosphere

15. Which radio fre&enc% )ands &se the troposphericscattering principle for propagation of radio *a+es?a. )elo* 37,). 37, to 7,c. 7, to ,#. ! &b%$

16. 7osses ca&sed )% sin effect and the $2: =po*er>loss are classified as *hat t%pe of loss?


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a. dielectric losses). radiation losses. Cpp$r l++$+d. $:2losses

18. What is the range of the characteristic impedanceof lines &sed in act&al practice?a. 2" to "0 ohms

b. 0 ' 600 /4+c. '00 to 500 ohmsd. 500 to 600 ohms

20. $t meas&res the e9istence of +oltage +ariation on aline&. *8R). W:c. reflectometerd. meggameter

21. $t is &sed to meas&re standing *a+e ratioa. 3W: meter). W: meter . r$9l$'4$'$r

d. meggameter

22. he direction of *hat field is &sed to designate thepolari!ation of a *a+e?a. Magnetic fieldb. $l$'ri 9i$l#c. ind&ction fieldd. radiation field

2#. What is the 3W: of a #00 ohms line terminated)% a resisti+e load of 200 ohms?&. .). 0.''c. #00d. 200

24. What is the radiation resistance of a half*a+eantenna in free space?a. "0 ohmsb.73 /4+c. 6# ohms. #00 ohms

2". o* is directi+it% of a collinear arra% affected *henthe n&m)er of elements is increased?&. Dir$'i%i' ir$&+$+). Directi+it% decreasesc. nchangedd. $t depends

2'. he parasitic arra% can )e rotated to recei+e ortransmit in different directions. What is the namegi+en to s&ch an antenna?a. circ&lar arra%). rositic arra%c. )roadside arra%#. r'&r &rr&

25. What is another name for the (e+erage antenna?a. signal antenna). analog&e antenna

. :&%$ &'$&d none of these

26. What ca&ses the c&rrentcarr%ing area at thecenter cond&ctor of a coa9ial line to )e restricted toa small la%er at the s&rface?a. Miller effect). Armstrong effect

c. 7ens effect#. *;i $99$'

28. What term is &sed to identif% the for*ard progress+elocit% of *a+efronts in a *a+eg&ide?a. Phase +elocit%b.


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d. r$$

#5. he +al&e of a resistor creating the thermal noise isdo&)led< *hat happens to the generated noisepo*er?a. al+ed). @&adr&pledc. do&)led

d. /&$#

#6. ne of the follo*ing micro*a+e diodes is s&ita)lefor +er% lo*po*er oscillators onl%.a. T$l). ;&nnc. $MPAd. 7-A

#8. ne of the follo*ing diodes is not &sed as amicro*a+e mi9er or detector.a. PIN #i#$). cr%stal diodec. chott%)arrier dioded. )ac*ard diode

40. $t is &sed to allo* one antenna to )e &sed forreception or transmission *itho&t m&t&alinterference.a. Diple9er). Dpl$>$rc .circ&latord. atten&ator

41. $t states that the ma9im&m rate of informationtransmission depends on the channel )and*idth.a. Colpitts la*). Clapp la*c. Armstrong la*#. !&r'l$ l&:

42. :ight no*< ;M is the accepted cell&lar standardinBBBBBBBB.

a. /&rope ). -orth America c. o&theast Asia

#. All 9 '/$+$

4#. he angle s&)tended )% the earth atgeos%nchrono&s comm&nication satellite isa. 7.31?). "1.4c. 120d. '0

44. Which area of the *orld first deplo%ed cell&larser+ices for commercial &se?

&. *i&%i& ). Central America c. Central Asia d. /astern /&rope

4". What is the )asic ser+ice &nit of cell&lar telephon%?a. location areab. $llc. P7M- ser+ice area

d. MC ser+ice area

4'. A #; terminolog% for -et*or Monitoring %stema. perations and Maintenance Centerb. Op$r&'i *ppr' *+'$4c. -et*or Monitoring Centerd. -et*or perations Center

45. When does )roadcast station cond&ct ane&ipment test?a. d&ring dela% time). an% timec.. d&ring night time#. #ri $>p$ri4$'&l p$ri#

46. he first ;M call in the *orld too place in ,inlandonBBBBBB.a. Ma% 1< 2001). -o+em)er 2#< 1880c. &ne "< 188##. @l , 55

48. A net*or element acting as a )ridge )et*een a

mo)ile net*or and a fi9ed net*or is called aa. MC). A&C.


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"". BBBBBBBBis the method of encoding a&dio signals&sed in standard 1"44 K)itsF24 channel PCMs%stem.&. -l&:). Ala*c. Kla*d. la*

"'. he con+ersion of digital signal into analog forp&rposes of transmitting into the telephone line isdone thro&ghBBBBBBBB.a. $D-). AM.4#$4d. ro&ter

"5. Who coined the term (l&etooth?a. arald (latand). :ed at. @i4 &r#&/

d. 7e*is /rol

"6. What t%pe of *a+e is made &p of sine *a+es at thef&ndamental fre&enc% and all the harmonics?&. +&:''/ :&%$). s&are *a+ec. sine *a+ed. cosine *a+e

"8. What is the )a&d rate of a digital circ&it thatprocess 2000 elements per second *ith 20 K!signal inp&t?a. 20 )a&db. 2000 bc. 10 )a&dd. 2 )a&d

'0. When *as the first #; introd&ced in the maret?&. O'b$r , 200). -o+em)er 1< 2001c. Decem)er 1< 2001d. an&ar% 1< 2001

'1. Adding parasitic elements to an antenna *illGa. decrease its directional characteristics). decrease its sensiti+it%. Ir$&+$ i'+ #ir$'i&l /&r&'$ri+'i+d. $ncrease its sensiti+it%

'2. What ferrite rod de+ice pre+ents the formation of

reflected *a+es on a *a+eg&ide transmission line?a. reflectorb. i+l&'rc. *a+e trapd. W: refractor

'#. What is the p&rpose of stacing elements on anantenna?a. sharper directional pattern). increased gainc. impro+ed )andpass#. &ll 9 '/$ &b%$

'4. he characteristics of the magnetron o&tp&t p&lsethat relates to acc&rate range meas&rement is itsGa. amplit&de). deca% time. ri+$ 'i4$d. d&ration

'". An X)and radar operates in *hich fre&enc%)and?a. 12 ;!). 24 ;!c. 46 ;!#. =-2


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a angs motionless in space a)o&t #' 0$>p-5 @). 1.' 9 10e9p18

c. 1.22 9 10e9p1' d. 1.8 9 10e9p14

88. he amo&nt of po*er per &nit area in optical fi)er iscalled&. Irri&$). :adiancec. :eflectanced. Permeance

100.7ight at 1."" &m in air has *hat energ% in e3?a. 1.2 e3). 1 e3c. 0.' e3#. 0.= $

est - pre board april 2007

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