Reply to Verizon fios on demand is pixelated and skips

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[quote=Anonymous][quote=Anonymous]I’m a physicist with long experience in electronics and optics, and I have solved this problem on two set-top boxes in my house.  I removed the coax cable between the wall jack and the set-top box and replaced it with one that was 3” shorter.  End of problem.  What??  Why should something so silly actually do anything?  Well, here’s what I think is going on:  The RF radiation that enters that cable can be weakly reflected from its ends.  If the wavelength of the particular channel has the correct relationship to the cable length, a resonance can be set up, just like blowing into a flute creates distinct tones.  This resonance can cause problems.  Changing the length of the cable by a quarter of a wavelength shifts it out of resonance.  The channels I had problems with use frequencies 727 MHz and 636 MHz.  (You can find this using Menu/Settings/System Information/Info in FiOS). The formula for the wavelength in this kind of coax cable is: wavelength in inches = 7793 / frequency in MHz.  This gave 7793/727 = 10.7 inches and 7793/636 =12.3 inches.  A quarter of those lengths is 3 to 4 inches.  I had a cable lying around that was about the right length – being off by an inch or two wouldn’t matter.  I got lucky the first time.   If this had not worked, I would have tried some other lengths within a wavelength of the original cable length.[/quote]

Are you for real?  Respect, chum. You're a smart one.[/quote]

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