Low-pass filter

A low-pass filter is a method used to remove high-frequency components from a signal, allowing only low-frequency components to pass through. This technique is often used in structural health monitoring to eliminate noise and interference in sensor signals.

When using a low-pass filter, it is important to consider the following factors:

• Cutoff frequency: this is the point at which the filter begins to reduce the signal. The cutoff frequency is determined by the specific application and the desired level of noise reduction.
• Filter order: this refers to the number of poles in the filter. A higher order filter will have a steeper roll-off, which can be useful for removing high frequency noise, but it can also introduce distortion to the signal.
• Filter type: There are different types of low-pass filters with different properties, such as Butterworth, Chebyshev or elliptic filter, each with different properties and trade-offs.
• Verification: After applying a low-pass filter, it is important to verify the filtered signal to ensure that it meets the desired specifications and that important information has not been lost or distorted.

It’s important to note that while low-pass filtering is a commonly used method in structural health monitoring, it is not the only method. Other methods such as high-pass filtering, band-pass filtering, and frequency-domain analysis can also be used to extract useful information from sensor signals. Choosing the right filter and filter parameters is crucial and it depends on the specific application, the type of sensor, and the nature of the signal. Therefore, it is a good practice to consult with experts in the field of structural health monitoring to choose the best filtering method for a specific application.