Thanks for your reply. I dont think I fully understand yet! My background is with vibration measurement more than digital system design, so help on understanding how the electronics work is really appreciated. I dont believe your statement "the bandwidth of the signal is always lower than 1/2 the sample rate, therefore aliasing is not an issue" really holds. Aliasing is avoided by ensuring vibration frequencies outsde that bandwidth are excluded from the signal before it is digitized. This doesnt just happen because you chose a certain sample rate(or bandwidth) they need to be physically removed. My understanding is that for a conventional ADC a sharp analogue low pass filter is required to ensure all out of band frequencies (i.e. frequencies above the nyquist frequency or half sample rate) are sufficiently attenuated before digitization. If this doesnt occur then they will be aliased into the data stream and can not be removed by any amount of digital filtering post digitization. So my question was what the characterisitc of the analogue front end filter actually are? Or is there some other ADC methodology being used? The only other means of avoiding aliasing that I know of is via a delta-sigma ADC approach that significantly oversamples, low pass filters and then decimates. But as the sample rate of the accelerometer is only 3200Hz (actually 1600Hz according to the spec sheet) and max ODR is 1600 Hz, I assume its not a delta-sigma ADC. As a conventional ADC, the analogue pre filter characteristics are significant. This would need to have a sharp cuttoff, e.g. 4th order or higher butterworth, no higher than 800Hz (or 1600Hz if sample rate is actually 3200 Hz). thanks in advance for any responses.
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