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   alt.engineering.electrical      Electrical engineering discussion forum      2,547 messages   

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   Message 550 of 2,547   
   William Sommerwerck to grizzledgeezer@comcast.net   
   Re: Crystal frequency for monochrome vid   
   08 Feb 13 09:59:20   
   
   XPost: sci.electronics.components, sci.electronics.design, sci.e   
   ectronics.equipment   
   XPost: sci.electronics.repair   
   From: grizzledgeezer@comcast.net   
      
   wrote in message news:84eah8l5sjc287vef3emrj5df0hm042ubu@4ax.com...   
   On Fri, 8 Feb 2013 06:49:10 -0800, "William Sommerwerck"   
    wrote:   
      
   >>> The B&W contains spectral peaks at multiplies of line and field rate.   
   >>> For (stationary) images, there is no energy between the spectral lines.   
      
   >> This is not correct, unless every line is like every other line. The normal   
   >> variation in vertical details causes the peaks to "smear" somewhat.   
      
   > I have quite often used the following example what the B&W signal   
   > looks like:   
      
   > There are quite often repeating hills every 15625 Hz with a tree   
   > standing at every 25 Hz starting from the top of the hill   
      
   > With severe wind (image movement) the tree branches will  be mixed   
   > with each other, making it impossible to separate luminance and   
   > chrominance properly.   
      
   True, but you're missing the point of what I said. "Movement" is sufficient,   
   but not necessary. Changes in  vertical detail produce same effect. That is,   
   no ordinary object is the same from line to line.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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