Om. Solomon, THE USE OF DFT WINDOWS IN SIGNAL-TO-NOISE RATIO AND HARMONIC DISTORTION COMPUTATIONS, IEEE transactions on instrumentation and measurement, 43(2), 1994, pp. 194-199
The discrete Fourier transform (DFT) can be used to compute the signal
-to-noise ratio (SNR) and harmonic distortion of a waveform recorder.
When the data record contains a non-integer number of cycles of the si
ne wave, energy leaks from the sine wave and its harmonics to adjacent
frequencies. Reference [1) describes a windowed DFT method for comput
ing the RMS value of a sine wave from the magnitude of the main lobe o
f its DFT and recommends the use of minimum energy windows. We present
criteria for choosing the DFT window. A constraint for the window coe
fficients is derived to insure that quantization error does not influe
nce the estimate of the amplitude of a sine wave from the main lobe of
its DFT.