The multi-frame loaded 2M signal is the information of which time period?

Question

Options

• A500us
• B125us
• C500ms
• D125ms

• A
  79% (30)
• B
  8% (3)
• C
  3% (1)
• D
  11% (4)

Explanation

Option A (500μs) is correct because a multi-frame in the 2M (E1, 2.048 Mbit/s) signal structure consists of 4 basic frames, and each basic frame has a duration of 125μs - so 4 × 125μs = 500μs total for one complete multi-frame period.

Option B (125μs) is the duration of a single basic E1 frame (256 bits ÷ 2.048 Mbit/s), not the multi-frame - a common trap since it's a real, correct value, just for the wrong unit of framing. Options C and D (500ms and 125ms) are wrong by a factor of 1,000 - they confuse microseconds (μs) with milliseconds (ms), which would be entirely different timescales irrelevant to frame-level signal structures.

Memory tip: Anchor on "125μs = 1 basic frame," then multiply by 4 for the multi-frame → 500μs. The "multi" in multi-frame signals ×4, and the answer follows the same 1:4 ratio as the two correct-looking options (125 → 500).

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