>If two variables have a Gaussian pdf, the standard deviation of the >combination should be the square root of the sums of the squares of >the standard deviations of the individual variables. For example if I > combine two noise sources, each having a Gaussian noise with 1 mV =3D > standard deviation, the sum will have a standard deviation of 1.414 >mV. > So, sure enough, the "P-P" value will be only 1.4 times the "P-P" of > either original signal. > Thank you very much for the reply. As you said, "if each noise source had a Gaussian distribution with a standard deviation of 1 mV, the sum will have a standard deviation of 1.414 mV, and the "P-P" value will be 1.4 times the "P-P" of either original signal." But, what if the standard deviations are not equal? The P-P value would not be the root mean square times either of the original. Tom ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu