Bruce Griffiths wrote: > John Miles wrote: > >> I see what you mean, Bruce, but why are the two sidebands considered >> incoherent, just because they're noise? Since the IF is 0 Hz, the other >> sideband appearing at the analyzer input jack is a folded image of the same >> noise spectrum, right? Given that, shouldn't the SSB correction be -6 dB >> rather than -3 dB? >> >> >> > The phase angle between the USB and LSB noise components is random when > translated to baseband so when averaged over time the resultant > amplitude is the same as if one just added the powers of the 2 components. > When the 2 sidebands are coherent the phase shift between them is fixed > so that their amplitudes add (vectorially). > The phase angle between the LSB and USB components when translated to > baseband depends on the modulation mechanism creating them. > With both LSB and USB components translated to baseband one has no > additional information so that some "reasonable" assumption has to be made. > > Nonsense, should have said:
The phase angle between the USB and LSB noise components is random when translated to baseband so when averaged over time the resultant amplitude is zero whilst the average power of 2 combined 2 components is just the sum of the powers of the 2 components. When the 2 sidebands are coherent the phase shift between them is fixed so that their amplitudes add (vectorially). The phase angle between the LSB and USB components when translated to baseband depends on the modulation mechanism creating them. With both LSB and USB components translated to baseband one has no additional information so that some "reasonable" assumption has to be made. Bruce > Bruce > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
