Attenuation to crosstalk ratio
Encyclopedia
Attenuation-to-crosstalk ratio, ACR, is the most important result when testing a link because it represents the overall performance of the cable. ACR is a mathematical formula that calculates the ratio of attenuation
to near-end crosstalk for each combination of cable pairs. ACR is expressed as a figure in decibels (dB), between the signal attenuation produced by a wire or cable transmission medium and the near-end crosstalk (NEXT). In order for a signal to be received with an acceptable bit error rate, the attenuation and the crosstalk must both be minimized. Crosstalk can be reduced by ensuring that twisted-pair wiring is tightly twisted and is not crushed, and by ensuring that connectors between wire and cable media are properly rated and installed.
Positive ACR calculations mean that transmitted signal strength is stronger than that of near-end crosstalk. ACR can be used to define a signal bandwidth (i.e. 200 MHz for category 6) where signal to noise ratios are sufficient to support certain applications. The maximum frequency for which positive ACR is assured provides a benchmark to assess the usable bandwidth of twisted-pair cabling systems. EIA
/TIA
specifies specific values for ACR in order to meet the various categories of cable.
Attenuation
In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, X-rays are attenuated by lead, and light and sound are attenuated by water.In electrical engineering and telecommunications, attenuation affects the...
to near-end crosstalk for each combination of cable pairs. ACR is expressed as a figure in decibels (dB), between the signal attenuation produced by a wire or cable transmission medium and the near-end crosstalk (NEXT). In order for a signal to be received with an acceptable bit error rate, the attenuation and the crosstalk must both be minimized. Crosstalk can be reduced by ensuring that twisted-pair wiring is tightly twisted and is not crushed, and by ensuring that connectors between wire and cable media are properly rated and installed.
Positive ACR calculations mean that transmitted signal strength is stronger than that of near-end crosstalk. ACR can be used to define a signal bandwidth (i.e. 200 MHz for category 6) where signal to noise ratios are sufficient to support certain applications. The maximum frequency for which positive ACR is assured provides a benchmark to assess the usable bandwidth of twisted-pair cabling systems. EIA
Electronic Industries Alliance
The Electronic Industries Alliance was a standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They developed standards to ensure the equipment of different manufacturers was compatible and interchangeable...
/TIA
Telecommunications Industry Association
The Telecommunications Industry Association is accredited by the American National Standards Institute to develop voluntary, consensus-based industry standards for a wide variety of ICT products, and currently represents nearly 400 companies...
specifies specific values for ACR in order to meet the various categories of cable.