Digital transmission methods If a digital signal must travel over a single conductor plus a reference ground (two wires total), in which transmission mode must it be sent?

Introduction / Context:
Signal wiring constraints often dictate whether data is sent in serial or parallel form. Understanding the physical link (number of conductors available) helps determine the feasible transmission mode for digital communication between devices.

Given Data / Assumptions:

• Available conductors: one signal line plus a ground reference.
• Digital data stream to be delivered from a transmitter to a receiver.
• No additional clock or strobe lines are specified.

Concept / Approach:
Parallel transmission requires multiple simultaneous conductors (one per bit, plus control lines). With only one signal conductor and ground, all bits must be sent sequentially over time, which is the definition of serial transmission. Encoding, clock recovery, and line coding (e.g., NRZ, Manchester) make this practical.

Step-by-Step Solution:
Count conductors: only one signal line is present.Parallel data requires as many conductors as there are data bits → not possible here.Therefore, bits must be time-multiplexed over a single line → serial transmission.

Verification / Alternative check:
Common interfaces like UART (TX/RX, each a single line plus ground) and one-wire buses demonstrate serial transfer over minimal conductors.

Why Other Options Are Wrong:
Parallel: needs multiple lines; impossible with one signal conductor.Analog: the data is digital; analog is a different signaling category.Slow speed: speed is not inherently determined by the number of wires.

Common Pitfalls:
Assuming “single wire” implies low speed; modern serial links can be very fast with appropriate coding and termination.

Final Answer:
serial.