Carrier-frequency estimation based on the location of the spectra peak of a windowed sample of carrier plus noise

The frequency of an unmodulated (CW) carrier frequency transmission may be estimated by identifying the location of the peak value of the spectrum of a windowed sample of T-seconds duration. The authors quantitatively evaluate the effect of window shape and length (leakage) as well as the effect of additive broad-band noise on the accuracy of this method of estimation. An interesting result is that neither elaborate `shaping´ of the window, nor the use of the `least mean-squared´ error method will have much advantage over the use of the spectral peak in a rectangularly windowed sample, unless the signal-to-in-band-noise ratio is of the order of 50 dB or better.