In color television systems, how are the chrominance subcarrier and its sidebands fitted into the standard channel bandwidth without severe interference to the luminance spectrum?

Introduction / Context:
Color TV adds chrominance information via a subcarrier and sidebands to an existing luminance signal within a fixed channel width. Clever spectral placement prevents visible cross-talk patterns while maintaining compatibility with monochrome receivers.

Given Data / Assumptions:

• Chrominance is modulated onto a subcarrier (e.g., PAL ~4.43 MHz).
• Luminance spectrum contains strong line-rate harmonics.
• Goal: fit chroma within the same channel without objectionable interference.

Concept / Approach:

Frequency interleaving places the subcarrier at a frequency offset such that its sidebands fall between dominant luminance spectral lines (which are concentrated at multiples of half the line frequency), effectively interleaving spectra and reducing cross-luminance and cross-color artifacts.

Step-by-Step Solution:

Verification / Alternative check:

PAL/NTSC design uses subcarrier frequencies carefully tied to line frequency fractions (e.g., 283.75 * f_H in NTSC) to achieve interleaving.

Why Other Options Are Wrong:

• “Adjustment/Changing/Amalgamation” are vague and do not capture the line-locked interleaving principle.
• Time-division techniques are not how analog color subcarrier coexists in the channel.

Common Pitfalls:

Assuming simple filtering suffices; in reality, precise frequency planning is essential for compatibility and artifact control.

Final Answer:

Frequency interleaving