ECE :: Communication Systems
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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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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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Consider the following statements about Rhombic antenna
- It is non resonant
- It is a broad band antenna
- It is ideally suited for HF transmission
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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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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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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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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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A 400 W carrier is modulated to a depth of 75 percent. The total power in modulated wave will be
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In a colour TV receiver the bandwidth of RF amplifier is
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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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4N0 
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= 14.14 μV.
Δf (frequency deviation) is independent of fm , Δf depends only upon amplitude of message signal.