Problem-Solving Suggestion

Need a Sine wave Removed?

Sine wave removal or extraction from ones data is a two-step process that requires our CurvFit and SpectrumSolvers software. Here is a procedure to remove sine waves from digital data:

1. First execute SpectrumSolvers to find what are your key frequencies. For example, say SpectrumSolvers shows two key frequencies. Take these two frequencies as starting values for CurvFit's 'sine' model (question #10 input). Setup CurvFit to match these two frequencies against your data (lets call your data file A1).

2. If CurvFit converges okay, then your CurvFit Error plot should be called A2 (i.e. A2 = A1 - n * Sinewaves) where 'n' is number of sine waves removed (n = 2 in this example). Your error data is located in your '~4plots.dat' file. It is the third column. Delete or comment out the first few lines up to where the 4 column data begins. Then delete columns 2 and 4. Save the remaining save data as your 'A2' file.

3. If A2 data still shows a sine wave is involved, run SpectrumSolvers on A2 data and find what other frequencies are involved. Say SpectrumSolvers finds one more frequency from A2 data. Add this frequency to your CurvFit input (question #10) parameters. Now this example would have 3 frequencies. The A1 data is still in use as you rerun CurvFit. An edited CurvFit Error plot (see '~4plots.dat' file) will be your new A2 data file. If this new A2 data still shows sinusoidal ripple then back to the beginning of this paragraph you go. (Warning: CurvFit does a least-square error fit to converge that looks like a ripple. Can't remove this ripple!)

Once you make it here, A2 data is your A1 data minus 'n' sine waves.