# About filtering and composing signals

I have got three signals, acc_x, acc_y, acc_z. I need to compose them in order to compute the magnitude of the acc. I would like to ask the following question:

what is better opt1 or opt2? or opt3?:

**opt1**: first apply a filter to reduce the noise to each single signal and then compute the magnitude or,

**opt2**: first compute the magnitude and then apply a filter to the composed to reduce the noise?

**opt3**: Any other good suggestion?


Any of your suggestion would be very appreciated.