251. The radio receivers mostly used now a days are
252. The reactance of coupling capacitors, for DC quantities, is
253. An AM wave is given by s(t)AM = 20 (1 + 0.5 cos 103t + 0.3 cos 104 t cos 106 t) the modulation index of the envelope is
254. The modulating frequency in frequency modulation is increased from 10 kHz to 30 kHz. The bandwidth is increased by
255. A sinusoidal signal with peak to peak amplitude of 1.536 volt is quantized into 128 levels using a mid-rise uniform quantizer. The quantization noise power is
256. An FM wave is made to pass through a frequency tripler. If original modulation index is mf, the output of tripler has a modulation index equal to
257. A balun provides an impedance transformation of
258. A signal m(t) with bandwidth 500 Hz is first multiplied by a signal g(t) where . The resulting signal is then passes through an ideal low pass filter with bandwidth 1 kHz the output of the low pass filter would be
259. If γ = (S0/N0)/(Si/Nm) where S0 and S1 are signal power output and signal power input and N0 and Nm are noise power output and noise power input, the value of γ for SSB-SC and DSB-SC amplitude modulated system respectively are
260. Consider the draw backs Slope overloadSerration noiseGranular noise Which of these draw backs does Delta modulation have?
261. It is required to increase the maximum range of a radar by a factor of two. The peak power transmitted in the radar system has to be increased by a factor of
262. Armstrong F.M. transmitter performs frequency multiplication in stages
263. A source generates three symbols with probabilities 0.25, 0.25, 0.50 at a rate of 3000 symbols per second. Assuming independent generation of symbols, the most efficient source encoder would have average bit rate is as
264. The filter circuit for feeding tweeter has
265. The name modem is a contraction of terms modulator demodulator.
266. The use of SSB
267. In which List of the constitution 'Economic and Social Planning' is included?
268. Video signals are transmitted through
269. A TV receiver has 20 kV EHT supply and total beam current (for 3 electron guns) of 1500 μA. The power handled by IHVT is
270. Some possible disadvantages of high level modulation in TV transmitters are Video monitor has to supply high video voltages upto several hundred volts into highly capacitive loads drawing high current at video frequenciesThe grid modulated stage presents a varying load to its driverThe linearity and high video driving power present design problems Out of above which are true?
271. Beam width of an antenna is expressed in
272. In broadcast television, the number of lines per frame is chosen to be odd number to
273. In a picture tube, the video signal is applied to
274. If frames are repeated at 60 Hz and each frame has 525 lines, the time for scanning one horizontal line (for progressive scanning and no interlacing) is about