Waveform analysis

Conrad Hoffman · 23rd March 2008, 12:11 AM

I need to analyze some varying periodic signals and can easily record a wav file. Is there any freeware or easy technique to locate zero crossing points (or peaks) and get the time data into Excel? I need the rate of change of the frequency/period. I could probably write a program to do this, but don't want to reinvent the wheel if I don't have to.

jcx · 23rd March 2008, 02:53 AM

Linear's free LtSpice/SwCad III imports .wav, then all of their waveform analysis options are available, look at the .MEAS doc in the help file, also examples on the LtSpice Yahoo group

for a small # of crossings .Meas with cross=1, cross=2 ... could get the intervals

you could even "build" a FM demodulator in sim if you needed to using PLL, Slope filter, or PWM demodulation

another free option is the MathCad workalike SciLab, also with .wav import and all of the number crunching power you could want (well actually a little limited by the 50Meg "stacksize" so audio processing/editing is probably out of the question)

23rd March 2008, 12:11 AM	#1
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	Waveform analysis I need to analyze some varying periodic signals and can easily record a wav file. Is there any freeware or easy technique to locate zero crossing points (or peaks) and get the time data into Excel? I need the rate of change of the frequency/period. I could probably write a program to do this, but don't want to reinvent the wheel if I don't have to. __________________ I used to be an audiophool like you but then I took an arrow to the knee.

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23rd March 2008, 02:53 AM	#2
jcx diyAudio Member Join Date: Feb 2003 Location: ..	Linear's free LtSpice/SwCad III imports .wav, then all of their waveform analysis options are available, look at the .MEAS doc in the help file, also examples on the LtSpice Yahoo group for a small # of crossings .Meas with cross=1, cross=2 ... could get the intervals you could even "build" a FM demodulator in sim if you needed to using PLL, Slope filter, or PWM demodulation another free option is the MathCad workalike SciLab, also with .wav import and all of the number crunching power you could want (well actually a little limited by the 50Meg "stacksize" so audio processing/editing is probably out of the question)