Signal-to-noise ratio estimation assumes that the system operates stationarily, and that signal and noise add linearly the response.    From Wordnik.com.  [PLoS ONE Alerts: New Articles] Reference

According to the arguments during the large demonstration in Rostock, with which it was among other things more than 400 hurt policemen to have given, by which on demand more only one stationarily had to be treated, the law in magistrate's court procedure at least ten demonstrator inside sentenced.    From Wordnik.com. Reference