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Date Posted: 06:06:17 02/24/02 Sun
Author: Potter
Subject: Re: PAL B/G Decoder
In reply to: Gaz 's message, "PAL B/G Decoder" on 16:55:47 02/21/02 Thu

Start with virtually any 3chip design say Canton 4.2 for functionality and simplicity and if the audio's not affected leave out the subcarrier decoder (the PLL) - PAL software examples are on Jens page for something to build on. They all work on the same principle IE monitoring edges produced by signal transitions and substituting new sync pulses to eliminate tricks like split sync - it's all done in the software. The false sync pulses you mention should not be affecting the colour burst or active video.

>Hi!!! And thanks for reading this post! :)))
>
>Ok i finally decide to try to build a decoder for the
>system
>that's used around here, once it has past about 5
>years since the start of the cable service here, and
>still nothing else to use but the original box from
>the cable company.
>Why am i doing ...
>Well i think it's a rip-off the prices for that
>services, and off-course i think it will be fun to
>crack they holly secret of scrambling system.
>For starting i need some from everybody, and i hope to
>help some on the future, after all we all wanna have
>fun!
>
>About the system:
>- PAL B/G
>- Cable company (TvCabo Portugal)
>- Set-up-Box Scart or RF from NL Exsad (www.exsad.com)
>
>The scrambling:
>- Replacement of original Sync by new Sync pulses
>(both horizontal and vertical) at quasi random
>positions
>- Insertion of fake H-Sync signals at moving
>positions.
>- Random insertions of fake V-Sync signals at moving
>positions.
>- Random Color Polarity changes.
>- Scene change controlled Video Polarity inversions.
>- Transparency: the scrambling system leaves all
>VBI-lines unaffected, so the full VBI is available for
>services, i.e. teletext.
>
>I think there's nothing already made for this, i
>belive i will have to "create" a new decoder ...
>But has i'm really starting, If you know wich hardware
>and software would be more suitable for this case,
>please leave a reply for this post or write me to my
>e-mail.
>
>Thanks for you all, and congratulations for this
>project (i belive it keep us more freedom).
>
>Greattings!
>Gaz

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Replies:

  • Re: PAL B/G Decoder -- tvsync, 14:32:08 03/02/02 Sat
  • Re: PAL B/G Decoder -- Gaz, 15:34:52 03/02/02 Sat
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