Copper Cable Test Parameters

Wiremap

Fundamental connectivity test

Verifies all eight conductors are connected correctly. Identifies:

  • Opens: Broken conductors with no continuity
  • Shorts: Conductors touching each other
  • Reversed Pairs: Positive and negative swapped
  • Crossed Pairs: Conductors on wrong terminals
  • Split Pairs: Incorrect pair combinations

Length

TDR-based measurement

Cable length measurement uses time-domain reflectometer (TDR) technology. TIA-568 limits: Maximum channel 100m, permanent link 90m.

Insertion Loss

Signal attenuation (dB)

Measures signal power lost as signals travel through cable. Expressed in decibels (dB), increases with cable length and frequency. Higher frequencies experience greater loss.

Return Loss

Impedance mismatch (dB)

Measures signal reflecting back due to impedance mismatches. Higher values are better (less reflection). Poor return loss indicates termination problems or damaged cable.

NEXT

Near-End Crosstalk (dB)

Measures unwanted signal coupling between wire pairs at the transmitting end. Measured between each pair combination. Higher dB values indicate better isolation.

FEXT / ELFEXT

Far-End Crosstalk (dB)

Measures signal coupling at the receiving end. ELFEXT normalizes measurement relative to insertion loss. Alien crosstalk (ANEXT/AFEXT) measures coupling between adjacent cables.

Propagation Delay

Signal travel time (ns)

Measures time for signals to travel through cable. Delay skew is the difference between pairs, critical for protocols transmitting on multiple pairs simultaneously.

Fiber Optic Test Parameters

Insertion Loss

Total optical loss (dB)

Total optical power lost between input and output. Sources include fiber attenuation (~0.35 dB/km single-mode), connector loss (0.2-0.5 dB), and splice loss (0.05-0.1 dB).

Optical Return Loss

Reflectance (dB)

Quantifies light reflected back toward source. PC connectors: ~-30 dB. UPC: -50 dB or better. APC: -65 dB or better. Important for single-mode and DWDM applications.

Length

OTDR measurement

OTDR calculates length from time-of-flight of light pulses. Accurate measurement requires correct index of refraction values for the specific fiber type.

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