InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
Space wave may be a direct wave or wave reflected from earth. |
| Answer» Strength of space wave depends on distance as it suffers attenuation. | |
| 302. |
It is desired that transmission line and load should match for a range of frequencies. The best method is |
| Answer» When matching over a range of frequencies is desired, double stub is necessary. | |
| 303. |
In a fascimile reproduction time to scan one line is 2 ms. If it has 4% blanking, the visible trace time is |
| Answer» (2 ms) (1 - 0.04) = 1.92 ms. | |
| 304. |
As the frequency increases, the absorption of ground wave by earth's surface |
| Answer» Because of this reason ground waves can be used for frequencies upto about 1600 kHz only. | |
| 305. |
The velocity of sound waves in air |
| Answer» v ∝ T. | |
| 306. |
The range of a cordless telephone is about |
| Answer» The range depends on quality of instrument and is about 100 m. | |
| 307. |
The rate at which information can be carried through a communication channel depends on |
| Answer» Rate of information depends on bandwidth. | |
| 308. |
Some types of traps used in video IF amplifier of colour TV are |
| Answer» All these are used. | |
| 309. |
Direct and reflected sound waves may interfere with each other. |
| Answer» PAS use moving coil microphones. | |
| 310. |
A carrier is simultaneously modulated by two sine waves having modulation indices of 0.4 and 0.3. The total modulation index will be |
| Answer» m1 = 0.4, m2 = 0.3 . | |
| 311. |
In standing wave pattern on a transmission line |
| Answer» When standing wave is set up voltage maxima and current minima and voltage minima and current maxima coincide. | |
| 312. |
An earth mat for a communication tower consists of |
| Answer» The number of radials is large and depth is about 30 cm. | |
| 313. |
Degaussing in a picture tube means |
| Answer» Since gauss is a unit of magnetic flux, degaussing means removal of magnetism. | |
| 314. |
If the bandwidth is increased by 2, the γ γ (where γ is the ratio of SNR of output to SNR at input, FM is frequency modulation and AM is amplitude modulation) is increased by a factor of |
| Answer» Doubling of frequency increase SNR in frequency modulation by 4. It has no effect in AM. | |
| 315. |
In the figure , the output () will be |
| Answer» | |
| 316. |
A carrier wave carries information. |
| Answer» Carrier does not have any information. | |
| 317. |
Frequency shift keying is used mostly in |
| Answer» Frequency shift keying (FSK) is a system of frequency modulation used in telegraphy. | |
| 318. |
In radar systems PRF stands for |
| Answer» PRF in radar systems means pulse repetition frequency. | |
| 319. |
Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal. |
| Answer» 0.1 Pa (= 0.5 x 10-4 W/m2) is taken as standard sound pressure for defining S/N ratio of microphones. | |
| 320. |
A telephone exchange has 9000 subscribers. If the number of calls originating at peak time is 10, 000 in one hour, the calling rate is |
| Answer» Calling rate is the number of calls per subscriber. | |
| 321. |
If C is capacity of noisy channel, (bits/s), δ is bandwidth Hz and S/N is signal to noise ratio, then |
| Answer» This is Shannon-Hartley theorem. | |
| 322. |
() and () are used to generate an FM signal. If the peak frequency deviation of the generated FM signal is three times the transmission bandwidth of the AM signal, then the coefficient of the term cos [2(1008 x 10)] in the FM signal (in terms of the Bessel Coefficients) is |
| Answer» As, we known FM, s(t) Frequency deviation = 3 . (AM Bandwidth) = 6 fm and β= 6 is given in (d) only. ωc + n ωm = (1008 x 103)2p 2p x 106 + n. 4p x 103 = (1008 x 103).2p n = 4 So, β = 6, n = 4 hence answer is 5j4(6). | |
| 323. |
Tracking of extra terrestrial objects requires |
| Answer» All the three are required. | |
| 324. |
Radio broadcasts are generally |
| Answer» Frequency modulation gives noise free reception and is used for radio broadcasts. | |
| 325. |
If the frequency of a wave 20 Hz, the time period is |
| Answer» . | |
| 326. |
The colour subcarrier and sidebands produced by its modulation with the chrominance signals are accommodated in the standard channel width by the process of |
| Answer» In frequency interleaving the space between bundles is used for colour signal. | |
| 327. |
In FM signal with a modulation index is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of |
| Answer» Frequency multiplier increase the deviation, . | |
| 328. |
In colour TV receiver, varactor diode is used for |
| Answer» In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer. This capacitance is used for tuning. | |
| 329. |
Push pull amplifier is |
| Answer» Push pull is a power amplifier. | |
| 330. |
When the channel is noisy, producing a conditional probability of error = 0.5; the channel capacity and entropy function would be, respectively, |
| Answer» . | |
| 331. |
In CCIR-B system, the time between start of one H syn. pulse and next is |
| Answer» The frequency of H pulses is 15625 Hz. Hence . | |
| 332. |
Counterpoise is used in coils having |
| Answer» Counterpoise is a horizontally buried wire used to provide low grounding resistance in high resistivity soils. | |
| 333. |
The number of noise sources in a BJT are |
| Answer» Shot noise, partition noise and thermal noise. | |
| 334. |
Energy content of atmospheric noise |
| Answer» Atmospheric noise decreases as frequency is increased. | |