'time delta' function on statistics express VI and counters

[glazerjq]

Hi everyone,

I'm working on creating a counter (specifically creating a heart beats per minute display for a school project). I'm using a trigger and gate express VI along with a statistics express VI with the 'time delta' output enabled. What I want for now is a display of time in between triggered samples which I don't seem to be getting. The time delta numeric indicator displays a constant value. I'll attach the VI (which includes a control to change frequency of a sine wave, time delta should decrease as frequency increases). Any ideas?

Thanks,

Joe

Download File:post-7118-1165203270.vi

[Mellroth]

The time delta numeric indicator displays a constant value.

Hi,

the reason you get time delta = 0.001, is that the sampling frequency is set to 1kHz in the "Simulate Signal" node. The time between sampled points will therefore be 0.001s.

If you want to measure the period of the generated signal, look in the "Waveform measurements" palette, there you will find express VIs that measure the period/frequency/duty cycle/etc..

/J

[glazerjq]

Thanks for the response. What I actually wanted to do was measure the time difference between peaks. For my project, the input won't be a signal generation, but a signal from a microphone receiving sound from a subject's heart. My question really is: is there a VI that outputs time difference between peaks?

Thanks,

Joe