DSP - Restore Clipped Signal

[TimC]

In the process of collecting vibration data, a large component of one channel was clipped. The data was acquired on an analog recorder and has been subsequently digitized. (The analog tapes are still available.) The digitizer's sampling frequency was about 10-times that of the dominant waveform that was clipped so there is a significant amount of "good" data (nominally 10 points per cycle). What is the best way of reconstructing the signal in the clipped regions? It seems that a simple interpolation using y=A*Sin(w*t) should work -- but I've got a brain-block when trying to solve the simultaneous equations.

The frequency does vary with time but is stable over many (>50) cycles.

The data was from an intermediate state of a structure that cannot be recreated.

 

[tomirvine]

I would use a cubic spline method.

I will show you how to do this if you send me a data sample in ASCII text format.

Tom Irvine
Email: tomirvine@aol.com

http://www.vibrationdata.com

 

[TimC]

Tom,

Thanks for the offer but I've gone off on a slightly different tack for now. Even though the data is compromised, I want to use a reconstruction technique that has the best (theoretical) chance of replicating the data. I had given thought to the cubic spline -- but the signal is best approximated by a sin fuction. So, even though the computational overhead is greater, what I'm in the process of doing is using snippets of the good data, (immediately before and following the clipped section) and performing a nonlinear (least squares) curve fit to a sin function. Once I complete the programming, I will compare the results with output from a cubic spline and a neural network.
I've got a sneaking suspicion that the statistical performance of all three methods will be about the same.

Thanks and Happy Holidays,
-Tim-