What issue does the Nyquist filter help to mitigate in signal transmission?

The Nyquist filter is specifically designed to mitigate intersymbol interference (ISI) in signal transmission. ISI occurs when the signals from successive symbols interfere with each other, which leads to potential confusion in interpreting the received signals. This overlap can result from the limited bandwidth of the transmission medium, causing symbols to spread out in time and blend into one another.

The Nyquist filter achieves this by limiting the bandwidth of the transmitted signal while ensuring that it has a controlled shape, which helps maintain the integrity of the individual symbols. It accomplishes this by ensuring that the signal has zero crossings at the sample points corresponding to the symbol intervals, effectively minimizing the risk of ISI. By adhering to the Nyquist criteria, the filter helps to maintain clear distinctions between symbols and enhances the overall reliability of data transmission.

This focus on reducing ISI makes the Nyquist filter a crucial component in systems that require high data integrity, such as digital communications and data storage systems.