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.


2003-02-17 7:38 pm
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)