User`s guide

9H423-26 Cabling Requirements
A-10
• Near End Crosstalk (NEXT) Loss - The NEXT cites noise and interference
within a pair, or more, of conductors where one conductor induces crosstalk on
the other.
The Near End refers to coupling that takes place when the transmit signal
entering the link couples back to the receive conductor pair a that same end of
the link; in other words, the near-transmitted signal is picked up by the near-
receive pair. Refer to Table A-6.
NEXT loss decreases as the frequency increases according to the following
formula:
NEXT(f) ≥ NEXT(0.772) - 15log(f/0.772)
• Propagation Delay - Electrical signals in conducting wires travel at a speed
dependent on the surrounding medium. This is called propagation delay. For
Horizontal UTP cable, the propagation delay for any pair at 10 MHz should not
exceed 5.7ns/m.
Table A-6. NEXT Loss (Worst Pair Combination) for 100 m
Freq (MHz) CAT 3 (dB) CAT 4 (dB) CAT 5 (dB)
0.150 53 68 74
0.772 43 58 64
1 415662
4 324753
8 274248
10 26 41 47
16 23 38 44
20 - 36 42
25 - - 41
31.25 - - 39
62.5 - - 35
100.0 - - 32