DATA COMMUNICATION LAB (EC-605) - Important Questions

Differentiate serial and parallel transmission and show NRZ vs RZ encoding waveforms; carry out a short experiment to transmit a sample byte and analyze timing. Include timing diagrams, measured bit durations and explain synchronization issues observed during the experiment.

Study NRZ and RZ codes. For the bit sequence 1101001, draw the waveforms for NRZ-L, NRZ-I and RZ (50% duty). Explain advantages and disadvantages of each scheme and discuss how each affects DC component and clock recovery in a receiver.

Demonstrate and explain RS-232 interface: describe voltage levels, connector pinout and handshake signals; draw timing and level diagrams for a typical asynchronous transmission showing start bit, data bits, parity (if used) and stop bit(s).

Compare NRZ and RZ in terms of DC component, bandwidth and ease of clock synchronization. For an alternating bit pattern (e.g., 101010...), find the fundamental frequency component in terms of the bit interval $T$. Express the fundamental frequency $$f_{1}$$ using $T$.

Design an experiment to transmit the ASCII character 'A' (hex 0x41) using NRZ-I coding over an RS-232 link at 9600 baud. Show the bit-timing diagram including start and stop bits, and calculate the total transmission time for the character. Describe the expected waveform at the receiver and how you would verify correct reception.

Explain RZ signaling with variable duty cycle. For a duty cycle value \(d\) (expressed as a fraction of the bit interval) and bit interval $T$, sketch the RZ waveform for duty cycle $d=0.25$ and compute the approximate frequency of the first spectral null (the first zero) in terms of $T$ and $d$. Express the first null frequency $$f_{null}$$ in terms of $T$ and $d$.