XPost: alt.comp.os.windows-10, alt.home.repair, sci.electronics.design   
   From: pcdhSpamMeSenseless@electrooptical.net   
      
   wmartin wrote:   
   > On 1/2/23 07:01, Phil Hobbs wrote:   
   >> John Larkin wrote:   
   >>> On Sun, 1 Jan 2023 22:14:49 +0100, "Carlos E.R."   
   >>>  wrote:   
   >>>   
   >>>> On 2022-12-25 22:12, micky wrote:   
   >>>>> sci.electronics.design added.   
   >>>>>   
   >>>>> Technical qustion about wave valleys and troughs and if two radio   
   >>>>> playing the same station will be in phase wrt all frequencies, or if   
   >>>>> some will cancel out?   
   >>>>   
   >>>> If I remember correctly, each amplifier stage inserts a delay and a   
   >>>> phase shift in the signal it processes.   
   >>>   
   >>> Microseconds. Equivalent to a tiny fraction of an inch at sound   
   >>> propagation speed.   
   >>>   
   >>>>   
   >>>> Each capacitor or coil inserts a phase difference between voltage and   
   >>>> current.   
   >>>   
   >>> Tiny.   
   >>>   
   >>>>   
   >>>> So, you can assume that if they are the same model, the should be in   
   >>>> phase. Not trivial to calculate.   
   >>>>   
   >>>>   
   >>>> Then, if the distance to the transmitter is one half wave lenght, there   
   >>>> will be a 180 phase difference in the high frequency arriving.   
   >>>   
   >>> Which won't affect the audio.   
   >>   
   >>   
   >> That's all true for AM, and mostly true for FM, but not for SSB.  The   
   >> BFO phase comes out in the audio signal, so the audio phase will vary   
   >> at infrasonic or low-audio rates.   
   >>   
   >> Cheers   
   >>   
   >> Phil Hobbs   
   >>   
   > Infrasonic? OIC... we need a SSB decoder for radio bigfoot!   
      
   )   
      
   The phase changes at the beat frequency between the BFO and the place   
   where the carrier would be if it were still there.  You want that to be   
   slow, because it's annoying if it's in the audio range.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
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