Which characteristic of a filter implies the ability to reduce unwanted signals?

The ability of a filter to reduce unwanted signals is best indicated by attenuation. Attenuation refers to the reduction in amplitude or strength of a signal as it passes through the filter. In the context of filters, higher attenuation means that the filter is more effective at diminishing the power of unwanted signals, ensuring that only the desired signals are transmitted or passed through. This characteristic is crucial in various applications, such as audio processing, communication systems, and electronic circuits, where it’s essential to maintain the quality of the desired signal while minimizing the interference from unwanted signals.

In contrast, passband response describes the behavior of the filter within its passband, where signals are allowed to pass with minimal attenuation. Phase response involves how the filter affects the phase of the signals passing through it and does not directly relate to the reduction of unwanted signals. Gain refers to the amplification of signals, which is not inherently related to the ability of a filter to minimize undesired signals. Thus, attenuation clearly stands out as the characteristic that directly signifies the filter’s ability to reduce unwanted signals.