What percentage of the actual amplitude will be visible for a 15 Hz wave with a HFF setting of 15 Hz?

To understand the percentage of the actual amplitude that will be visible for a 15 Hz wave with a high-frequency filter (HFF) setting of 15 Hz, it's important to consider the function of the high-frequency filter in relation to the frequency of the signal being measured.

When the high-frequency filter is set at the same frequency as the wave being analyzed (in this case, both at 15 Hz), it allows signals at or below this cut-off frequency to pass through effectively while attenuating higher frequencies. This means that a 15 Hz wave, when sampled, will be accurately represented by the HFF because it does not exceed the filter threshold.

In practice, many diagnostic signals exhibit complex waveforms, and even if a signal is at the cut-off frequency, there is often significant attenuation of the amplitude. When a signal is at the exact frequency of the high-frequency filter's cut-off, typically around 71% (or approximately 0.7) of the amplitude will be visible in an ideal situation, as some inherent filtering characteristics lead to spreading and diminishing of amplitude.

Therefore, based on the filter characteristics, the percentage of the actual amplitude visible for a 15 Hz wave with the HFF setting of 15 Hz aligns most