Hi It can be either. The easy example is a tone that is outside the entire band of the noise. If it is a “real” noise spectrum, that’s never going to be the case. There will always be *some* noise at the tone frequency in a real system.
Bob > On Jan 5, 2018, at 2:49 PM, Dana Whitlow <k8yumdoo...@gmail.com> wrote: > > 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. _______________________________________________ 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.