Thank you so much for the comments.
yes I did realise that I would have to do that.
sorry i should have been more specific
The equation for the natural logarithmic decay function is y=e^-kt where k is the decay constant.
but i was confused how to go about multiplying this by the sine function that I'm simulating.
how do I ensure that the correct points are lined up?
or do I just code this in discrete components and not worry about how they line up.
I will worry about the real acquisition later but for the simulated signal I am guessing
I would have to set the sample rate, and the number of samples and that would give me
the time to sample.
then convert that into some sort of array., then multiply this out.
then what happens to the data - where does it go?
when I use the express vis if I change the parametres I'm measuring eg extract the fundamental tone.
then as soon as the amplitude is adjusted in real time the tone info also disappears.
ie if the signal decays to zero the tone information disappears. which is not what I want
I would like to record this somehow as well, as the signal will only last for about 1 second at the most.
but will be approx 100 - 1000hz range so there should be lots of chances to get a sample before it decays to zero.
I would like to be able to record (simulate) a decaying waveform, display the result, and then use the standard functions
fft etc on the captured waveform.
then repeat if neccesary
thanks for your help
steve