How I can find the time between two points on a signal.

I need to find the time between the first and last exceedence of absolute 0.05g on earthquake accelerogram. Please guide how I can do that?

Answer 1

[Wayne King]

I'm just using a simulated signal, x, substitute you signal for x in the calls to find()

   x = 0.05*randn(100,1);
   idx1 = find(abs(x)>0.05,1,'first');
   idx2 = find(abs(x)>0.05,1,'last');