BERAN

Proven Condition Monitoring Solutions

Glossary

  • B

    • Band Pass Filter

      A band pass filter defines a range of vibration frequencies – the filter bandwidth - within which all frequencies are allowed to pass, thus rejecting or attenuating all frequencies above and below the band.

    • Beat Frequency

      A beat frequency will occur when two very close frequencies combine together at a particular location to form a single frequency. The amplitude will vary from a maximum to a minimum over a period of time – the beat frequency – which is related to their closeness. The closer the original frequencies are together the lower the beat frequency. It may be observed on a turboprop aircraft when the speeds of the two engines are not perfectly matched and will detected as ‘vibration/noise’ which rises and falls over a period of a few seconds.

    • Bins and Binwidth

      When an FFT is created the energy in the total signal bandwidth is measured at descrete frequency intervals, the resulting information ‘lines’ are placed in their appropriate ‘bins’. The greater the resolution of the FFT the narrower will be the ‘binwidth’ and the greater the detail which may be obtained, typically we see a resolution of 400, 800 or 1600 lines or bins.

    • Bump Test

      If an object or component, with an accelerometer attached, is struck, bumped or rapped either by hand or using a special hammer at an irregular interval whilst acquiring a asynchronous vibration signature. The resulting spectral line will provide a good estimation of its natural frequency.