A rotating machine has a genuine vibration component at

PHYSICS · Subjective · Fermi University Physics · Computational Physics · Electronics, Instrumentation & Communication · Scientific programming for physicists

Computational Physics, Ch Spectra of sampled signals

Problem

37\,\mathrm{Hz}

. (a) The vibration is first sampled at

f_s = 50\,\mathrm{Hz}

. State the Nyquist frequency and predict the frequency at which the

37\,\mathrm{Hz}

component will appear in this record's spectrum. (b) The sampling rate is then raised to

f_s = 100\,\mathrm{Hz}

. Predict where the component appears now, and state the one-sentence diagnostic that would tell someone, from the two spectra alone, that the peak in part (a) was an alias rather than a real line.

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