Modulation types and “modulation index” interpretations: Match each scheme with the most appropriate modulation-index characterization (as commonly presented in introductory exams). List I (Modulation) List II (Index characterization) A. DSBFC (AM with full carrier) 1. μ > 1 B. DSBSC 2. μ > 0 C. SSB 3. ∞ 4. μ, any value

Introduction / Context:
“Modulation index” μ is rigorously defined for standard amplitude modulation with a residual carrier (DSBFC). For suppressed-carrier schemes (DSBSC, SSB), many textbooks present an equivalent or limiting characterization for comparison, which appears in exam match-the-following questions.

Given Data / Assumptions:

• DSBFC: a carrier is present; μ is the ratio of message amplitude to carrier amplitude (practically μ > 0 and typically ≤ 1 to avoid over-modulation).
• DSBSC: carrier is zero; conventional μ relative to carrier is undefined and modeled as tending to ∞ in comparative tables.
• SSB: single sideband transmission; if μ is forced into a comparative table, it is often listed as μ > 1 relative to an equivalent carrier reference.

Concept / Approach:

We align with the common exam convention: DSBFC → μ > 0; DSBSC → ∞ (no carrier); SSB → μ > 1 when expressed in comparative “index” terms used in some introductory summaries. Note that in rigorous SSB analysis, “μ” is not used; power/efficiency is treated directly without a carrier reference.

Step-by-Step Solution:

Verification / Alternative check:

Intro AM tables in many exam guides show DSBSC with “μ = ∞” and SSB with “μ > 1” as qualitative placeholders to emphasize carrier suppression and efficiency improvements relative to DSBFC.

Why Other Options Are Wrong:

• Assigning finite μ to DSBSC contradicts its zero-carrier definition.
• Labeling DSBFC as μ any value ignores over-modulation distortion beyond μ = 1 in standard AM.

Common Pitfalls:

Treating these “indices” as rigorous in SSB/DSBSC; they are comparative heuristics. For precise design, compute power and bandwidth directly.

Final Answer:

A-2, B-3, C-1