hello, i'm using an accelerometer (ADXL311) which outputs analog voltage in proportion to g's for X and Y axes. i'm trying to use this to manipulate sound when a person is 'running', basically as speed increases above a certain threshold, but having problems with my formulas for speed. i've managed to graph these two actions with consistent visual results - it's visually clear when someone is running, etc., but haven't been able to correctly translate this into a usable formula. my known variables are gX, gY, time, and i'm assuming that i'll have to take periodic samples and calculate an average, but so far, i've managed nothing that makes sense. can anyone help in a language for dummies? i can handle the electronics more or less, but had (embarrassingly enough :uhh:) to look the formula for speed. thanks!