Sampling and Filtering Data for ISO8041 Compliance and Human Body Vibration Data Weighting

Various human body vibration measurements and assessments are defined in the ISO2631, ISO5349, ISO6954 standards and also in the EEC vibration directive 2002/44/EC. These assessments are based on the analysis…

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Understanding Filter Characteristics

Recently when discussing with an engineering student the characteristics of filters, it became clear that some confusion exists around this subject area. This note attempts to explain¬†the differences between types of filter and the effects of the parameters of those filters. (more…)

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Audio Equalisation Filter & Parametric Filtering

When working with audio signals a common requirement is to be able to equalise, cut or boost various frequency bands. A large number of hardware devices on the market provide this capability. The key aspect is that such filters are able to control bandwidth, centre frequency and gain separately. There are broadly two classes of filter used, a “shelving” filter and an “equalising “filter (also known as a “peak” filter). A shelving filter is akin to low pass and high pass filters. An equalising filter is like a bandpass or band reject filter.

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Cleaning Up Data

When we have a very noisy signal with a large number of spikes and signal bursts then if all else fails try Median Filtering. This is a technique often used in cleaning up pictures. The operation is almost childishly simple in concept but we will save the details until we have examined an example.

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