[QuadList] NEC TBC

[C. Park Seward]

Chris has it right. The TBCs (as are most products) are made for  
markets and price points. A VTR made for a 1" will cost more and have  
better quality than a TBC made for 3/4" or 1/2".

With color-under formats, you don't need the bandwidth or S/N ratio  
that you do for a direct color TBC.

In fact, the best U-Matic TBC would be a direct color TBC that had the  
heterodyne card. Even the mighty Zeus has that option.

Best,
Park

C. Park Seward
Visit us: http://www.videopark.com



On Jul 11, 2009, at 11:34 AM, Chill315 at aol.com wrote:

> No easy way to compare TBC's.  There are a couple of things to look  
> for.
>
> 1    8 bit or 10?  If 10 more quantizing levels to allow better  
> pictures.
>
> 2    What is window?  For a vertical lock machine, It only has to be  
> one line.  Then you have the issue of providing advanced sync to the  
> machine to get the correct time out of the TBC and stay centered in  
> the window.
>
> 3    Direct color always has a better bandwidth so thus more detail  
> and quality of picture.  But the real issue is how good are the  
> filters.  The pre A-D filter has to be wide enough to not cause  
> artifacts and yet keep the video below the Nyquist frequencies.  The  
> post D-A filter has to be good enough to prevent ringing yet smooth  
> out the samples and keep bandwidth flat.  These are tradeoffs that  
> are made during the design of a TBC.  More with cost than anything  
> else.  I say that because it depends on the market that you are  
> marketing the TBC to.
>
> 4    Sample rates are always better at higher numbers.  4X  
> subcarrier is one that is popular in NTSC because you can do some  
> tricks in the color process.  Also if you are doing any size changes  
> it makes the math easier.
>
> 5    A TBC that is designed for heterodyne process will always look  
> worse than a direct one on a non heterodyne signal.  Just the nature  
> of the filters for Chroma and Luminance processing.
>
> Those are my thoughts.  And I am no expert.  These are just  
> observations over the years.
>
> Chris Hill
>
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