In the CCIR-B (625-line, 50 Hz field rate) television system, what is the time interval between the start of one horizontal sync (H-sync) pulse and the start of the next?

Introduction / Context:
Horizontal timing in analog TV standards like CCIR-B (PAL, 625 lines) determines line frequency, picture sampling along each line, and the placement of sync pulses. Knowing the line period is fundamental for scan timing, sync separation, and deflection system design.

Given Data / Assumptions:

• CCIR-B standard: 625 lines per frame, interlaced, 50 fields per second.
• Horizontal line frequency ≈ 15.625 kHz.
• We need the period between successive H-sync pulse starts (i.e., one full line period).

Concept / Approach:

The horizontal line period T_H is the reciprocal of the line frequency f_H. In CCIR-B, f_H ≈ 15,625 Hz, so T_H ≈ 1 / 15,625 s.

Step-by-Step Solution:

Verification / Alternative check:

Standard PAL timing tables list a 64 μs line period with ~52 μs active video and ~12 μs blanking/sync, confirming the 64 μs figure.

Why Other Options Are Wrong:

• 6.4 μs and 0.64 μs: off by factors of 10 and 100; much faster than CCIR-B line rates.
• 640 μs: off by factor of 10; would imply 1,562.5 Hz line rate, incorrect.
• 32 μs: half the correct value; not used in this standard.

Common Pitfalls:

Confusing field period (20 ms) and line period (64 μs), or mixing NTSC (525/60) and PAL (625/50) parameters.

Final Answer:

64 μs