Final answer:
The device that provides filtering on sub split return frequencies is a Band-pass filter. It allows a specific frequency range to pass and attenuates others outside that range. When capacitors are replaced by inductors in a circuit, the filter's function is reversed; high-pass becomes low-pass and vice versa.
Step-by-step explanation:
The mitigation device that provides filtering on sub split return frequencies is a Band-pass filter. A Band-pass filter allows frequencies within a certain range to pass through while attenuating frequencies outside that range. This is in contrast to Low-pass filters, which only allow frequencies below a certain threshold to pass, and High-pass filters, which only allow frequencies above a certain threshold to pass. Notch filters reject a specific band of frequencies and allow others to pass.
Regarding the replacement of capacitors with inductors in a filter circuit, if capacitors are replaced by inductors, the resulting filter will have the opposite function. An inductor in place of a capacitor in a high-frequency filter would create a low-frequency filter, and vice versa. Therefore, if a circuit was originally a high-pass filter with capacitors, replacing them with inductors would make it a low-pass filter, and if it was a low-pass filter, it would become a high-pass filter.