At a digital receiver in data communications, what is the process called that converts a modulated analog carrier back into a baseband digital bitstream so it can be processed by the computer?

Introduction:
In a typical digital communication system, the transmitter modulates a digital bitstream onto an analog carrier for efficient transmission over band-limited channels (radio, coax, fiber optics via electrical/optical carriers). At the receiver, the inverse operation extracts the original baseband data so a computer can process it. This question asks for the precise term describing that inverse operation at the receiver.

Given Data / Assumptions:

• The incoming signal is an analog, modulated carrier (e.g., FSK, PSK, QAM).
• The receiver must recover the original digital symbols/bits.
• Focus is on the carrier removal and symbol decision process, not merely timing recovery.

Concept / Approach:
Demodulation is the process that converts a modulated analog signal back into its baseband representation. For digital systems, demodulation maps received waveforms to symbol decisions, applies filtering/equalization as needed, recovers carrier phase/frequency, and outputs the bitstream. Modulation is the complementary transmitter operation; synchronizing/clock recovery is a supporting function that helps demodulation but is not a full replacement. Line coding (e.g., NRZ, Manchester) shapes baseband digital signals on a physical medium—again distinct from removing a carrier.

Step-by-Step Solution:

Verification / Alternative check:
In modems and radios, the digital signal processor chain includes carrier recovery, matched filtering, symbol timing, decision, and decoding—collectively framed under demodulation to deliver a digital bitstream to the host system.

Why Other Options Are Wrong:

• Modulation: transmitter-side process.
• Synchronizing: assists by aligning timing/phase but does not by itself produce the bitstream.
• Line coding: baseband symbol mapping (no carrier) used on some wired links.
• None of the above: incorrect because demodulation is the standard term.

Common Pitfalls:
Equating “analog-to-digital conversion” (ADC) with demodulation; ADC digitizes the waveform, while demodulation interprets it to recover the bits. Many receivers do both in sequence (ADC then digital demodulation), but the conceptual term here is demodulation.

Final Answer:
Demodulation.