VoyForums
[ Show ]
Support VoyForums
[ Shrink ]
VoyForums Announcement: Programming and providing support for this service has been a labor of love since 1997. We are one of the few services online who values our users' privacy, and have never sold your information. We have even fought hard to defend your privacy in legal cases; however, we've done it with almost no financial support -- paying out of pocket to continue providing the service. Due to the issues imposed on us by advertisers, we also stopped hosting most ads on the forums many years ago. We hope you appreciate our efforts.

Show your support by donating any amount. (Note: We are still technically a for-profit company, so your contribution is not tax-deductible.) PayPal Acct: Feedback:

Donate to VoyForums (PayPal):

[ Login ] [ Contact Forum Admin ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, 2, 3, 4, 5, 6, 7, 8, [9], 10 ]

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Date Posted: 10:31:00 02/14/02 Thu
Author: Jain
Subject: Re: How to bypass unscrambled Channel?
In reply to: Ronald 's message, "Re: How to bypass unscrambled Channel?" on 09:07:10 02/14/02 Thu

Hi Ronald
In order to get rid of wobling lines (or shifting) I give you the idea (which I already posted on forum)
to try to stop video to the pulse detectors as long as the 3 chip is locked. I'm going to try that in a few days (I mean I have a non tested hardware solution).
I have the advantage of never inverted video, so I think I'm going to use only one emiter follower at the input and one at the output, everything DC coupled and synchro restored (not built) at the proper level
Cheers
Jain



>>I can not help you with soft ideas (I'm not a
>>programming expert too) and I think nobody will do
>>that, not knowing how the local system works.
>>But... I'm also not happy with the 3 chip results, so
>>I'm trying to improve it (let's mention that I
>>installed 3 chip in a cable adapter that has IF
>>processing and I have the advantage to send the output
>>of the addapter -- output in Ch 3-- to a two way
>>spleater; from there, to the TV, one way, and I can
>>see the unscrambled channels, and the second way to
>>the IF imput of the cable addapter , and there 3 chip
>>decodes the scrambled channels and sends the result to
>>video output; the scrambled channels could be seen
>>with the tv set in video mode).
>>So, the first idea was to fix the AGC problem; the
>>second is to insert in the right place the blanking
>>part of the tv signal insted of letting 3 chip to
>>build an artificial synchonization -- and this with
>>the help of DC restoration circuit (I'm trying to
>>clarify some things that are not too clear to me with
>>this circuit in Digitalman). If you read very
>>carefully the messages I changed, in the last days,
>>specially with Potter, that is also an experimenter
>>guy, you'll see that all apply to your wishes too.
>>Tell me what it bother you (what you don't like when
>>you look at the screen) and we may find hardware
>>solutions, in absence of a soft one.
>
>My TV system is PAL-BG.
>
>I fixed my AGC problem using a 100uf in series with a
>VR from AGC PIN 19 of the IF IC TDA9801T to ground.
>The value of my VR is about 268ohm. So 100uf and 500R
>VR should be good enough. I can forget about build the
>S&H circuit which bugs me for months. Fine tune the VR
>and I think you can get very good picture quality and
>very even color. No white flashing on the top screen
>and no uneven color and brightness. I am using
>canton's Rev3 with addition of 733 to get superb
>quality. My oscillator ciruit is a 20Mhz Cystal and 3
>capacitor and a VCXO to get super stable quality. I
>also need to do more sampling on the burst by adding
>iorwf PORTB,w to make it more stable. Now my problem
>is watching unscrambled channel with the decoder and I
>get little wavy on the VBI. I have remove some nops on
>the Mainloop and begin to reduce the shifting. So now
>shifting stop but some lines can be seen wobbling. But
>I think it is better than shifting.
>
>If you are not satisfy with the picture quality by
>adding a 733 to the output will definitely enhance the
>output. I have tested it already but that will involve
>too many component. So I just add 1pc of 733 before
>Canton's Rev 3 input.
>
>So now I testing the SX50 version to compare my
>present result. Thanks to Potter that has been helpful
>to his source code but I am still not able to get it
>locked.

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Replies:

[ Contact Forum Admin ]

Forum timezone: GMT-8
VF Version: 3.00b, ConfDB:
Before posting please read our privacy policy.
VoyForums(tm) is a Free Service from Voyager Info-Systems.
Copyright © 1998-2019 Voyager Info-Systems. All Rights Reserved.