The first part of this lecture introduces the Fourier transform and how it is applied in chemical instrumentation. It is shown that the spectrum of resonances in a cylindrical tube can be determined by Fourier transformation of the "ring down" behavior of the device.
The ring-down measurement is but one example of an impulse-response experiment. The signal to noise ratio (SNR) of these experiments can be improved by adding together many repeat ring-down measurements. For random noise, the SNR increases as the square root of the number measurements coadded.
To prepare for this lab read Chapter 11.8.1 through 11.8.2 of your text book. The lecture notes will be made available at class time.