Q. A directional microphone gives an output of 0.5 mV whereas an omnidirectional one gives an output of 0.5 μV in the same position for the same sound pressure. The directivity of the directional microphone is

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Q. If Eb, the energy per bit of a binary digital signal is 10‾⁶ watt sec. and the one sided power spectral density of the white noise N0 = 10‾⁵ W/Hz, then the output SNR of the matched filter is

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Q. Consider the following statements about Rhombic antenna

1. It is non resonant
2. It is a broad band antenna
3. It is ideally suited for HF transmission

Which of the above are correct?

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Q. Assertion (A): A composite video signal has synchronising pulses.

Reason (R): It is necessary to synchronise the scanning process in the transmitter and receiver.

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Q. Noise with uniform power spectral density of N₀ω/Hz is passed through a filter H(ω) = 2 exp (-J ω ty) followed by an ideal low pass filter of bandwidth B Hz. The output noise power in watts is

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Q. Assertion (A): In standing wave pattern, the nodes and anti nodes are separated by half wave-length

Reason (R): When line is terminated in resistance RL, the standing wave ratio is SWR = Z0/RL or RL/Z0

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Q. An amplifier has an input resistance of 10 kΩ and the noise voltage is 10 μV. If two such resistances of 10 kΩ each are connected in series at the input, the total noise voltage is about

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Q. In a colour TV receiver the bandwidth of RF amplifier is

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Q. An FM signal with a deviation is passes through the mixer, and has its frequency reduced five fold. The deviation in the output of the mixer is

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Q. Some advantages of optical fibre cables are

1. small diameter
2. Immunity to cross talk and EM interference
3. Laser and LED modulation methods lend themselves ideally to digital operation

Which of the above are correct?

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Q. The contrast control in colour TV receiver is done by

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Q. The requirements of carrier frequency are

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Q. If N bits are lumped together to get an N-bit symbol, the possible number of symbols is

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Q. The received signal frequency at any time of a super-heterodyne receiver having IF = 456 kHz is 1 MHz. The corresponding image signal is

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Q. A 300 Hz sound wave of intensity 20 dB is transmitted by a 1500 kHz radio wave by frequency modulation. It is seen that instantaneous frequency varies between 1500.2 kHz and 1499.8 kHz, 300 times a second. If the intensity of sound wave is 100 dB.

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Q. If the average power of radar transmitters is 2 kW and the peak power of the transmitter is 1000 kW, what will be the duty cycle?

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Q. An analog signal is band limited to B Hz sampled at Nyquist rate and samples are quantized into 4 levels each with probability 1/4. The information rate is

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Q. The HV supply to a TV receiver is 25 kV and the total beam current for the three electron guns is 2000 μA. The power handled by IHVT is

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Q. The antenna diameter of a radar system is doubled. The maximum range will

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Q. Which of the following microphones works on the piezoelectric effect?

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