ECE :: Communication Systems
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An AM signal is detected using an envelope detector, the carrier frequency and modulating signal frequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope detector is
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For signal amplitude modulated to a depth of 100% by a sinusoidal signal, power is
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If transmitted power is 10 kW, the field strength at a distance d is 50 mV/m. If transmitted power is reduced to 2.5 kW, the field strength at the same point will be
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Some features of advanced mobile phone service are
- To provide telephone communication to a large number of telephone users within the area of a metropolitan only
- To use minimum amount of frequency spectrum
- To permit hand held as well as vehicle operation of telephone
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Three point tracking is achieved with
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In TV transmitter, visual exciter may consist of
- Video processing unit
- Visual modulator
- VSB filter
- Delay equaliser
- Frequency converter
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The positive peak of an AM wave is 16 V and the minimum value is 4 V Assuming single tone modulation, the modulation index is
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In a circuit the value of resistor is made four times. The noise voltage generated by this resistance will
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A resistor of 10 kΩ has an rms noise voltage of 1 mV under a certain set of conditions. A resistor of 20 kΩ under the same conditions will have an rms noise voltage of
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10-6 ≤ RC ≤ 250 μ sec.
times the power of unmodulated carrier 
times the power of unmodulated carrier 
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