In copper testing, what does ACR stand for and what does it measure?

• A. Acoustic Crosstalk Ratio; noise in the line.
• B. Attenuation to Crosstalk Ratio; the relationship between signal loss and crosstalk levels.
• C. Attenuation to Current Ratio; the current flow in the conductor.
• D. Amplitude Crosstalk Rating; crosstalk amplitude.

Answer: (B)

ACR stands for Attenuation to Crosstalk Ratio. It measures the relationship between how much the signal is attenuated over the cable (signal loss) and how much crosstalk is induced into adjacent pairs. In practice this single metric combines the effects of loss and interference to show how well a copper channel can carry the desired signal amid nearby coupling. It’s usually expressed as attenuation relative to crosstalk (often as a difference in dB), and a larger ACR generally indicates a more favorable balance between loss and crosstalk for the target performance.