music recorded at a studio is to be transmitted over a distance of 100 km using a wireless digital transmission system.

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music recorded at a studio is to be transmitted over a distance
of 100 km using a wireless digital transmission system. The signal
X (t) = 2 Sin (300πt) is produced by an electronic musical
instrument. This signal is first captured by a microphone (i.e.,
transducer), which converts the signal into an electric signal at
the same frequency but at an amplified amplitude of +5/-5 V. The
electrical signal then enters the transmitter of the communication
system. Here, the incoming signal is first digitized using a 3 bit
Analogue to Digital Converter. The digitized signal is then encoded
with Unipolar NRZ coding technique having a maximum voltage level
of +2V. Next, the digital data signal is modulated with a carrier
frequency of 3 GHz using Amplitude Shift Keying (ASK) technique.
The maximum amplitude of the modulated signal is +5V. The signal is
then transmitted using wireless media. The wireless channel has an
SNR threshold of 30 dB and a maximum bandwidth of 22 MHz. A
half-wave dipole (i.e., Omni-directional) antenna is used as the
transmission media. Due to external noise and atmospheric
conditions, the transmitted signal gets attenuated and unwanted
frequencies gets added to the signal.
A. For each stage of the above mentioned scenario, explain the
involved process and draw the relevant waveform. As relevant,
clearly mention the frequency, period, amplitude, sampling rate,
quantization levels, bandwidth, pulse rate, and bit rate. [Note:
when drawing the coded signal, consider only the first six
bits]
B. With reference to the encoded signal, explain the drawbacks
of Unipolar NRZ and suggest a method to overcome them.
C. Determine the dimension of the antenna and by then using the
knowledge on electromagnetic spectrum and applications, explain why
twisted-wire pairs or optical fibres cannot be used as the
transmission media.
D. By using your knowledge on time and frequency representation
of a signal, explain how the distorted signal can be re-constructed
at an intermediate repeater/re-generator.
E. If channel bandwidth is unlimited, briefly describe how each
stage can be further improved to provide a highquality signal at
the receiver.