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Re: Dynamic range

From: MachineryWatch
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There is the definition of Dynamic Range Eduardo referred to from the Vibration Institute and well known in signal processing discussions. This is related to the number of bits in the A/D converter used in your instrument. That is the maximum theoretical Dynamic Range for the A/D converter. There is also the EFFECTIVE or ACTUAL Dynamic Range which your instrument is capable of and this typically varies with chosen resolution. It may also depend on other electronic "noise" within your signal processing system or analyzer. When I say "signal processing system" I include any signal conditioning that might be used with your specific sensors. In general, Dynamic Range will increase with higher resolution FFTs. This is because the "noise floor" of the measurement drops when you select higher resolution for your FFT. So, the instrument specification that says it has 95dB Dynamic Range with 400 FFT lines of resolution, may actually have 96 dB or better Dynamic Range when using higher resolution FFTs. The reason for this is that electronics noise energy at the noise floor at any given frequency actually spreads into less adjacent bins when the resolution is higher. This reduces the "summing" effect of the noise, thereby lowering the noise floor, giving greater Dynamic Range. Skip Hartman

Last changed: October 16, 2007