Question

Below are the frequency ranges of different communication systems.Determine the bandwidth for each one. (i)AM radio: 535KHz-1605KHz =(ii) VHF TV:52MHz - 88MHz 02 mobile phone (downlink): 791MHz-821MHz (iv)EE mobile phone (uplink): 2500MHz - 2570MHz (v)UWB Radio: 3.1GHz 10.6GHz Explain two benefits of a large bandwidth to communications systems. Two stations (A and B) are connected. Determine the attenuation (in dB) if the following situations are true. The received power at B is 1w, the transmitted signal from A is 2w. The received power at B is 2w, the transmitted signal from A is 10w. (iii)The received power at B is the same as that at station A. The received signal at B is 1/4 of the transmitted signal from A. (v)The received signal at B is 1/10 of the transmitted signal from A. Two stations (A and B) are connected. Determine the gain (in dB) if the following situations are true. (i)The received power at B is 6w, the transmitted signal from A is 3w. (ii)The received power at B is 10w, the transmitted signal from A is 1w. The received power at B is the same as that at station A. (iv)The received signal at B is 5 times that of the transmitted signal from A. (v)The received signal at B is 3 times that of the transmitted signal from A. (i)A message signal is given as: Vm = 2 sin (2π * 3t) Sketch the signal in the time domain and frequency domain. A carrier signal is given as: Vc = 5 sin (2π * 5t) Sketch the signal in the time domain and frequency domain. (iii)If the message and carrier signals are modulated to product amplitude modulation: write down the expression and sketch the frequency domain spectrum.

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