Q. In a system an input resistance of 20 kΩ causes a noise voltage of 15μV. If two such input resistances each of 20 kΩ are used in parallel, the total noise voltage will be about

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Q. 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

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Q. 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

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Q. A balun provides an impedance transformation of

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Q. 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

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Q. Which of the following amplifiers is used for impedance matching?

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Q. Which of the following amplifiers has highest output impedance?

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Q. In a superheterodyne receiver, having no RF amplifier, the IF is 455 kHz. The image frequency at 1000 kHz is

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Q. Audio tapes have two tracks each 2.5 mm wide.

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Q. Which of the following amplifiers has a voltage gain of less than 1?

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Q. Some possible disadvantages of high level modulation in TV transmitters are

1. Video monitor has to supply high video voltages upto several hundred volts into highly capacitive loads drawing high current at video frequencies
2. The grid modulated stage presents a varying load to its driver
3. The linearity and high video driving power present design problems

Out of above which are true?

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Q. Beam width of an antenna is expressed in

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Q. In broadcast television, the number of lines per frame is chosen to be odd number to

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Q. In a picture tube, the video signal is applied to

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Q. 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

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Q. The name modem is a contraction of terms modulator demodulator.

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Q. The use of SSB

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Q. Video signals are transmitted through

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Q. 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

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Q. Full duplex operation

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