Resampling irregularly spaced XY data to proper waveform

Share icon

Wed, 03/09/2011 - 02:40 pm

I'm processing a significant amount of data sampled 'nominally' at 10Hz. In reality, it was 7.7 Hz briefly, then 9.6Hz and to make matters worse, the mean time step is 0.1s (the lower mean rates are due to sporadic time steps up to 0.3s long). In order to perform any significant analysis my data must be resampled to 10Hz but since it doesn't follow proper X-scaling, I can't use the Resample operation. I've encountered this before with data collected over a serial port where timestamps reflected arrival, not measurement times and was similarly stumped. Has anyone else developed a solution or technique for this issue? I'm developing a user function to linearly interpolate but hopefully some durable code already exists :)
It sounds like you have an XY pair and want to create a waveform by interpolation. There are a number of ways to do this. For a discussion, execute:
DisplayHelpTopic "Converting XY Data to a Waveform"


One of the ways described is to use Analysis->Interpolate and choose linear interpolation.

March 9, 2011 at 06:43 pm - Permalink

Igor 6.2 has a nice panel for converting an XY Pair to a waveform.

From Igor's Data menu, choose Packages->XY Pair to Waveform.

Chose the X and Y wave, the number of interpolated points, click Make Waveform, and off you go!

Screen capture of the XYPairToWaveformPanel.png attached.

--Jim Prouty
Software Engineer, WaveMetrics, Inc.
XYPairToWaveformPanel.png

March 9, 2011 at 07:21 pm - Permalink