Is this an audio tone, summed with audio noise whose spectrum surrounds that of the tone?
Dana On Fri, Jan 5, 2018 at 9:56 AM, Bob kb8tq <kb...@n1k.org> wrote: > Hi > > If I pass both a sine wave tone and a pile of audio noise through a > perfectly > linear circuit, I get no AM or PM noise sidebands on the signal. The only > way > they combine is if the circuit is non-linear. There are a lot of ways to > model > this non-linearity. The “old school” approach is with a polynomial > function. That > dates back at least into the 1930’s. The textbooks I used learning it in > the 1970’s > were written in the 1950’s. There are *many* decades of papers on this > stuff. > > Simple answer is that some types of non-linearity transfer AM others > transfer PM. > Some transfer both. In some cases the spectrum of the modulation is > preserved. > In some cases the spectrum is re-shaped by the modulation process. As I > recall > we spend a semester going over the basics of what does what. > > These days, you have the wonders of non-linear circuit analysis. To the > degree > that your models are accurate and that the methods used work, I’m sure it > will > give you similar data compared to the “old school” stuff. > > Bob > > > On Jan 5, 2018, at 6:27 AM, Attila Kinali <att...@kinali.ch> wrote: > > > > On Tue, 2 Jan 2018 23:34:18 +0100 > > Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > > > > [About AM noise being of equal power as PM noise] > > > >> Now, for actual sources this is no longer true. The AM noise can be much > >> higher, which is why it can be a real danger to the PM noise if there is > >> a AM to PM noise conversion. One source of such conversion can be the > >> amplification stage, but another could be a mistuned filter, which have > >> different amplitudes of the side-bands, which can create conversion as > >> the balance does not balance the same way anymore. > > > > Yes, exactly. I am currently trying to understand how noise affects > > circuits an how input and circuit noise get converted to output noise. > > First assumption that needs to be dropped is that the noise processes > > is purely additive and independent of the signal. This means that a > > noise process does not anymore produce equal AM and PM power. > > > > I think I have a 90% solution of the noise processes and conversions > > in a sine-to-square converter (aka zero-crossing detector, aka > comparator). > > But there is one process that keeps puzzling me. I think I know where in > > the circuit it must come from, but I have no explanation as to how it > happens. > > > > > > Attila Kinali > > -- > > It is upon moral qualities that a society is ultimately founded. All > > the prosperity and technological sophistication in the world is of no > > use without that foundation. > > -- Miss Matheson, The Diamond Age, Neil Stephenson > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.