Copper cable certification

In copper twisted pair wire networks, copper cable certification is achieved through a thorough series of tests in accordance with Telecommunications Industry Association (TIA) or International Organization for Standardization (ISO) standards.

These standards define the procedure to certify that an installation meets performance criteria in a given category or class.

(Traveling between 50% and 80% of the speed of light, an electronic wave requires between 417 and 667 ns to traverse a 100-meter cable.

Return loss is the measurement (in dB) of the amount of signal that is reflected back toward the transmitter.

The reflection of the signal is caused by the variations of impedance in the connectors and cable and is usually attributed to a poorly terminated wire.

A higher value is desirable as it indicates that less of the transmitted signal is coupled into the victim wire pair.

Low NEXT values on a UTP LAN used with older signaling standards (IEEE 802.3 and earlier) are particularly detrimental.

[citation needed] Excessive near-end crosstalk can be an indication of improper termination.

Attenuation-to-crosstalk ratio (ACR) is the difference between the signal attenuation produced NEXT and is measured in decibels (dB).

The ACR indicates how much stronger the attenuated signal is than the crosstalk at the destination (receiving) end of a communications circuit.

In many cases, even a small improvement in ACR can cause a dramatic reduction in the bit error rate.

DC resistance usually has less effect on a signal than insertion loss, but plays a major role if power over Ethernet is required.