But what I'm wondering, because this is important to the discussion, is the tone at a frequency encompassed on both sides by the noise band? Or is the tone outside the noise band?
Dana On Fri, Jan 5, 2018 at 1:35 PM, Bob kb8tq <kb...@n1k.org> wrote: > Hi > > The audio (or RF) tone is summed with “baseband" noise. 1/F noise seems > to be the flavor of the day in recent postings. The only reason to use > audio > in the example is that it is really easy to demonstrate things at audio > with > a sound card. > > Bob > > > On Jan 5, 2018, at 1:42 PM, Dana Whitlow <k8yumdoo...@gmail.com> wrote: > > > > 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. > > _______________________________________________ > 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.
