Dispersion penalty is a phenomenon in which pulses and edges of data signals traveling down a cable are smeared, making it difficult for the receiver at the other end to distinguish between ones and zeros. This phenomenon is caused by the different speeds at which different frequencies of light propagate through the cable, leading to the smearing of data signals over time. The result is a decrease in the sensitivity of the receiver compared to a short fiber, and is measured in decibels (dB).
Dispersion penalty is most commonly encountered in fiber optic cables, which use light to transmit data. The speed of light is different for different frequencies, and this causes the different frequencies of light to spread out as they travel down the cable. This phenomenon causes the data signals to become smeared, resulting in a decrease in the receiver’s sensitivity.
The dispersion penalty is proportional to the length of the cable and is most pronounced at the highest frequencies of light. As signals travel further down the cable, the dispersion penalty increases. This is why fiber optic cables are typically limited in length, with longer cables requiring more powerful transmitters to compensate for the dispersion penalty.
In addition to fiber optic cables, dispersion penalty can affect other types of cables, including electrical cables. In electrical cables, the dispersion penalty is caused by the capacitance and inductance of the cable, which also causes frequency-dependent delays.
Dispersion penalty can also be caused by the environment in which the cable is used. Factors such as temperature, humidity, and electrical interference can all contribute to the smearing of data signals and a decrease in the receiver’s sensitivity.
In summary, dispersion penalty is a phenomenon in which pulses and edges of data signals traveling down a cable are smeared, resulting in a decrease in the receiver’s sensitivity.