METHODS AND APPARATUS TO GENERATE AN ACOUSTIC EMISSION SPECTRUM USING AMPLITUDE DEMODULATION

Methods, apparatus, and articles of manufacture are disclosed. An example pre-amplifier includes a demodulator to generate an oscillating signal having a measurement center frequency, combine an acoustic emission signal and the oscillating signal to generate a sideband acoustic emission signal, sample spectral data of the sideband acoustic emission signal at an intermediate center frequency in an intermediate frequency bandwidth, and generate demodulated acoustic emission data based on a mapping of the sampled spectral data to the measurement center frequency, the measurement center frequency different from the intermediate center frequency, and a transmitter to transmit the demodulated acoustic emission data to a computing device.