What does a decibel (dB) measure in the context of cable links?

A decibel (dB) is a logarithmic unit used to measure the ratio between two quantities, commonly used in telecommunications and audio as it relates to power, intensity, or voltage levels. In the context of cable links, it specifically measures the ratio of the received voltage to the original voltage. This measurement is critical as it indicates how much signal strength is lost or gained as the signal travels through the cable.

When a signal travels through a cable, it may experience attenuation, which is the reduction in signal strength due to various factors, including cable resistance and interference. By using decibels, engineers can quantify this loss in a way that is easier to manage and understand because the logarithmic scale allows for large ranges of signal strengths to be represented compactly. Hence, measuring the ratio of received voltage to original voltage in dB provides valuable insight into the performance and efficiency of the cable link.

The other choices do not accurately reflect what a decibel measures. For instance, while the strength of the electrical signal over distance is related to loss, it is not the direct measurement represented by dB. Similarly, the total length of the cable and the speed of data transmission do not pertain directly to the logarithmic measurement of signal strength in