ELFEXT measures what?

• A. End-to-End Crosstalk; overall crosstalk across the channel.
• B. Equal Level Far-End Crosstalk; crosstalk measured at the far end with the same signal level.
• C. Near-End Crosstalk; near end interference.
• D. Far-Field Crosstalk; far away source interference.

Answer: (B)

Equal Level Far-End Crosstalk measures how much interference from one pair shows up at the far end of another pair, with the measurement done so the reference signal level is the same at both ends. This normalization removes the influence of cable losses and length, letting you compare cables fairly. In practice, you drive a signal on one pair and observe the induced signal on the far end of the victim pair; the ELFEXT value (in dB) represents the far-end crosstalk relative to the transmitted level, with the levels equalized. This distinguishes it from near-end crosstalk, which is measured at the source end, and from general far-end crosstalk that would be affected by insertion loss.