bandpass filters, vibration monitoring

Choosing bandpass filters for a machine depends on the application.

Many industries using heavy machinery are continuously innovating to reduce costs and improve reliability of machines. Two key trends stand out:

  • Predictive Maintenance (PdM)
  • Machine Monitoring

These solutions are critical to reducing machine and process downtime in construction, utility, industrial, and commercial equipment. Overall, factory managers and supervisors can leverage monitoring data to detect developing problems or even make continuous maintenance.

When properly implemented, machine monitoring improves the ROI on business-critical machines. Key among parameters for monitoring is vibration patterns in motors, rotors, and engines, among others.

bandpass filters, vibration monitoring
bandpass filters, vibration monitoring

What are bandpass filters?

Bandpass filters are electronic devices that have distinct signal operating bands and discriminate against all other frequencies. They are of two types:

  • Active bandpass filters
  • Passive bandpass filters

A filter is considered active if it integrates transistors and integrated circuits and has an external power source.


There are two types of bandpass filters: Active and Passive.


Passive bandpass filters, on the other hand, only consist of capacitors and inductors, which are not actively involved in the process.

Why We Need Filtering in Machines

Primarily, the role of bandpass filters in machines is removal of frequencies that would lead to undesirable operating state. The four most common filters for shock and vibration applications are:

  • Butterworth
  • Bessel
  • Chebyshev
  • Elliptical

There are two major ways to remove vibrations in machines:

  • High-pass filtering
  • Low-pass filtering

High pass filtering removes lower frequency vibrations that is present in all piezoelectric accelerometers. Effectively, these deal with DC bias and temperature effects. Low-pass filtering, on the other hand, handle aliasing defects.

Vibration Monitoring

Machine vibrations are wildly different in their severity and frequency. Vibration analysis plays a critical role in preventing failure of equipment, especially for rotating machines.

Vibration patterns say a lot about the condition of machines since each system has a distinct vibration signature. Deviations from an established signature is the tell-tale sign of anomalies in the system. To establish a highly efficient analysis system, it is important to maintain a record of vibration data over a long enough period.

Sensors are the foundation of vibration analysis. They are mounted on machines to gather data that can be used to assess the health of an operational machine. Advanced sensors gather the signature on the three axes of rotation (x, y and z) using accelerometers that detect both low and high frequencies. This data helps in simulating the smooth running of machines through a quantifiable amplitude detection. Put simply, the amplitude of a vibrating machine is defined by three variables:

  • Displacement (the distance travelled)
  • Velocity (rate of displacement)
  • Acceleration (rate of change of velocity)
bandpass filters, vibration monitoring

How Vibration Monitoring Works

As a plant manager or technician, being able to detect developing machine conditions. While periodic measures such as inspection can help detect problems early, it is only as effective as the data acquisition system employed.

For that reason, continual measurements based on sensors and automated data acquisition systems are more reliable. Some of the industries that leverage these systems include:

  • Oil and gas
  • Heavy machinery
  • Automotive and transportation
  • Energy

The choice of filters for a system depends on its application. Nonetheless, Butterworth and Bessel types are very popular for vibration testing and shock testing respectively. Also, any good system should offer consistent low pass filtering.

Choose Machine Saver for Your Vibration Monitoring Needs

Interested in saving time and money with vibration monitoring? Call Machine Saver, Inc. for more information on how our products can help your business. Call us at 1-832-471-8145 or click the button below to contact us online.

bandpass filters, vibration monitoring

User-Defined Bandpass Filters | Machine Saver, Inc. – Houston, TX