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

摘要

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 7-seconds duration. This estimate will, in general, be somewhat in error, and the error will depend on the length and shape of the window and the signal-to-noise ratio at the observing receiver. This paper quantitatively evaluates 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. In addition, it compares the method with an optimum “least mean-squared error” technique. 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.