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  #46  
Old 12-22-2014, 08:19 AM
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old_tv_nut old_tv_nut is offline
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Quote:
Originally Posted by dr.ido View Post
...Though the examples appear to only deal with still images and I doubt the page will be updated anytime soon. Similar techniques could probably used for ATSC.
The RF signal is precoded as video samples. If your PC monitor could sync to it, you would see a frame of noise-like "snow." The precoding is a far-too-slow software process to do real time video, but is a clever way to get a file that produces a valid signal for a still picture. This has to be done carefully so that a repeated frame of samples makes a valid continuous RF video signal. There would be many ways to make mistakes that would cause the receiver to hiccup or not decode this at all. The poster did an excellent job.

Edit: ATSC has a data frame structure lasting about 1/40 of a second. It also has a convolutional interleaver that spreads data from one frame to the next. This might pose a problem in creating a video frame representing a repeating RF signal of this duration.

Last edited by old_tv_nut; 12-22-2014 at 08:23 AM.
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  #47  
Old 12-23-2014, 08:20 PM
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ChrisW6ATV ChrisW6ATV is offline
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Quote:
Originally Posted by dr.ido View Post
It does lead me to wonder if any licensed amateur TV operators are doing digital now.
Yes indeed! Here is a good one in Australia:

http://www.vk3rtv.com/
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