Why is a high pass filter utilized in a demodulation/enveloping system?

A high pass filter is employed in a demodulation or enveloping system primarily to allow the passage of high frequency signals while rejecting lower frequency components. This is critical in vibration analysis because it enables the detection of modulation or envelope variations that may indicate underlying issues in machinery or structure, such as imbalance, misalignment, or looseness.

By filtering out the lower frequency noise and unwanted signals, the high pass filter helps to isolate the features of interest that are typically at higher frequencies. This leads to a clearer analysis of the phenomenon being investigated, such as the vibration signatures that correspond to specific fault conditions.

While the other answer choices mention aspects of signal filtering and amplification, they either misrepresent the main function of a high pass filter or focus on processing signals that do not align with the purpose of demodulation/enveloping systems. Understanding the role of the high pass filter is crucial for interpreting vibration analysis data accurately.