angelo.farina |
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| QUOTE (stepap @ 2/26/2017, 12:23 PM) dear Angelo (thanks for these great tools!)
I have a couple of questions:
1. Is there anything wrong if I use a sweep limited to 20-1000 Hz? I just wonder if the Aurora tools assume that one always uses sweeps between 20 and 20k Hz.
I'm characterizing tactile transducers and I'm only interested in frequencies below 1 kHz. I record the transducers' response with a measurement accelerometer (frequency response flat +/- 5% between 5-15000 Hz).
2. I usually measure simple vibration signals such as sine waves or band-passed noise, recording them as audio. The sensitivity specifications of the whole I/O chain are known, and making use of them I can easily obtain the corresponding values of acceleration in m/s^2. Of course for this to work, the first step is to make sure that the digital amplitudes in dBFS are meaningful. So my question is: does Aurora (namely, the convolution of sweep response with inverted sweep) alter in some way amplitudes? 1) You choose the minimum and maximum frequency according to your needs, but be aware of the rule of thumb: always start one octave below and end one octave above your useful frequency range. So, if you are interested in frequencies between 20 Hz and 1000 Hz, I would suggest to use a sweep from 10 Hz to 2 kHz. 2) of course the convolution with the inverse sweep changes the gain, reducing the noise by something as 60-80 dB, and consequently also the signal is scaled down of the same amount. It is still possible to calibrate the amplitude of the resulting impulse response, performing the convolution with the inverse sweep with a fixed gain, and then setting properly the value of Full Scale in the Acoustical Parameter module. |
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