The reduction in magnitude of a signal without changing the basic characteristics of the signal. Also, the amount of voltage reduction utilized to reduce large electronic signals down to full scale deviation on instruments such as FM tape recorders. This non-dimensional number us usually in even steps of 0.5, 0.2, and 0.1. Attenuation results from the transmission of vibration energy from one machine part to another (e.g., shaft to bearing housing) and also from signal conditioning circuits for some applications. (Bentley Nevada Corporation; Field of Rotating Machinery Measurement, Monitoring and Analysis)
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