Fundamental estimation with HarmonicEstimation function

In general, the first component is at the fundamental frequency. But if the number of components is chosen to high (or the db threshold too low) noise can produce a peak at a lower frequency.

Since small changes in the parameters can affect the outcome, I would advise to use the Analysis Wizard for Harmonic Estimation. Here one can easily change settings with a direct feedback on the results. Some background information is also available in the Online Help in the section Tutorials > Data Analysis > Harmonic Estimation Tutorial. The analysis object created can be changed into a formula and used as a starting point.