Which device or technique splits a high-speed signal into multiple frequency bands so several channels can share the same medium simultaneously?

Introduction / Context:
Multiplexing enables multiple independent signals to share one medium efficiently. Two classic families are Frequency-Division Multiplexing (FDM) and Time-Division Multiplexing (TDM), each using a different separation axis (frequency vs time).

Given Data / Assumptions:

• High-speed composite signal needs to be split into parallel channels.
• Separation is done by frequency bands, not time slots.

Concept / Approach:
An FDM device (frequency-division multiplexer) divides available bandwidth into non-overlapping frequency bands, assigning each channel a separate band. Guard bands reduce interference between adjacent channels.

Step-by-Step Solution:

Verification / Alternative check:
Analog cable systems and some radio backhauls use FDM by modulating each channel onto a distinct carrier frequency. Spectrum analyzers show multiple peaks corresponding to channels.

Why Other Options Are Wrong:

• t-switch: Not a standard multiplexing device term.
• modem: Modulates/demodulates a single data stream, not a multi-channel frequency splitter by itself.
• time-division multiplexer: Separates channels into time slots, not frequency bands.
• None of the above: Incorrect because FDM exactly fits.

Common Pitfalls:
Confusing TDM with FDM; assuming a modem inherently multiplexes many user channels in frequency; overlooking guard bands and channel spacing in FDM design.

Final Answer:
frequency-division multiplexer