# calculating RMS noise

I'm trying to measure whether a gyro i'm using is damaged. I've got raw data coming off, and a total RMS noise value from the data sheet of 0.38 deg/s-rms. I'd like to look at the raw data and compare it to this value. Is it really just a matter of root-mean square of the raw data, or is there some more complex formula?

right now i'm doing

$$\sqrt{\frac{1}{n} \sum_{i=1}^{n} Gx_k}$$

-
I was going to improve your formatting with MathJax but couldn't figure out what you meant with g_x_n. –  trygvis Jan 6 '13 at 8:34
the nth value of the x gyro -> g sub x sub n –  kolosy Jan 6 '13 at 18:27

## 1 Answer

Noise is added as RSS (Root Sum of Squares) but the noise itself is calculated as the sqrt (variance) - AKA the 1 sigma - the standard deviation.

Vn = sqrt(average((X-u)^2)) -> u = mean(X)

or

Vn = sqrt(average(X^2) -(average(X)^2)

-