Sinewave Fitting Based on Quantization Codes and Threshold Levels

This article illustrates a method for measuring the parameters of a sinewave using information about both the codes and threshold levels in a quantizer. It is shown that by adding knowledge about the threshold levels, the input signal parameters can still be recovered when very coarse quantization is applied in a case when the conventional three-parameter least-squares (LS) sinefit method fails to produce precise results. After the description of the procedure, its sensitivity to the accuracy of the frequency estimate is analyzed. Furthermore, the robustness of the method against uncertainties in the knowledge of the threshold levels is assessed. The estimation procedure is validated by extensive simulations and by experimental results obtained by measurement on a 12-bit data acquisition board. Results show that the proposed solution can significantly outperform the three-parameter LS sinefit if the number of quantizer bits is small.