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Communication systems
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ The antenna current of an AM transmitter is 8 A. When only the carrier is sent, but it increases to 8.93 A. When the carrier is sinusoidally modulated. The percentage modulation is nearly 0.7 [other wrong options] [Discuss in forum] 0.9 0.8 0.75 |
Q22 ⇒ Some possible disadvantages of high level modulation in TV transmitters are
1, 2 and 3 [other wrong options] [Discuss in forum] 1 only 1 and 2 only 2 and 3 only |
Q23 ⇒ For a plate-modulated class C amplifier the plate supply voltage is E. The maximum plate cathode voltage could be almost high as 4E [other wrong options] [Discuss in forum] 2E 3E 6E |
Q24 ⇒ An MTI compares a set of received echos with those received during the previous sweep. TRUE [other wrong options] [Discuss in forum] FALSE |
Q25 ⇒ The colour of an object is decided by reflected colour for opaque object and wavelength transmitted through it for transparent objects [other wrong options] [Discuss in forum] the reflected colour the wavelength transmitted through it none of the above |
Q26 ⇒ Television transmission is by space waves [other wrong options] [Discuss in forum] ground waves sky waves all of the above |
Q27 ⇒ When the length of antenna is a whole wavelength the radiation at right angles is zero [other wrong options] [Discuss in forum] the radiation at right angles is maximum the radiation is zero in all directions the radiation is maximum in all directions |
Q28 ⇒ If a dipole is meant for a frequency of 1 MHz, the length of each rod is about 50 m [other wrong options] [Discuss in forum] 5 m 20 m 100 m |
Q29 ⇒ Which of the following does not cause losses in optical fibre cables? Stepped index operation [other wrong options] [Discuss in forum] Impurities Microbending Attenuation in glass |
Q30 ⇒ Audio tapes have two tracks each 2.5 mm wide. FALSE [other wrong options] [Discuss in forum] TRUE |
Q31 ⇒ Human ear can detect sound intensities of the order of 10-13 W/m2 [other wrong options] [Discuss in forum] 10-4 W/m2 10-8 W/m2 10-18 W/m2 |
Q32 ⇒ In a TV studio the illuminance is about 1000 lux [other wrong options] [Discuss in forum] 200 lux 10000 lux 10 lux |
Q33 ⇒ A computer monitor uses 180 W in normal operation and 20 W in sleep mode. The computer is on all the 24 hours but is in sleep mode for 18 hours a days. The energy units saved in 30 days are 86.4 units [other wrong options] [Discuss in forum] 0.54 units 2.88 units 4.8 units |
Q34 ⇒ In a system using QASK and 4 bits to form a symbol, the required bandwidth is one-fourth of that in BPSK [other wrong options] [Discuss in forum] same as BPSK half of that in BPSK none of the above |
Q35 ⇒ Graphic equaliser system in stereophonic systems generally have 3 or 4 bands [other wrong options] [Discuss in forum] 1 band more than 8 bands large number of bands |
Q36 ⇒ A planar array radar uses a high gain planar array antenna. TRUE [other wrong options] [Discuss in forum] FALSE |
Q37 ⇒ In a communication receiver, a squelch circuit is normally inserted after detector [other wrong options] [Discuss in forum] before detector before mixer after power amplifier |
Q38 ⇒ In radar PRF depends on maximum range. TRUE [other wrong options] [Discuss in forum] FALSE |
Q39 ⇒ In colour television V and U signals are modified R - Y and B - Y [other wrong options] [Discuss in forum] same as I and Q signal same as R - Y and B - Y modified I and Q signal |
Q40 ⇒ A receiver has poor selectivity. It will also have poor blocking [other wrong options] [Discuss in forum] sensitivity double spotting diversity reception |
Or |