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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 26th Mar 2006, 11:12 am   #1
Kat Manton
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Default 405-Line TV from PC - First Pictures!

Hi,

Now I've put the Sony TV back together, I couldn't resist trying to find some way of seeing what I'm getting from the PC. I've not sorted out a VHF modulator yet, but remembered that if you push both the UHF and VHF buttons in together, the Sony 9-90UB will do 405-line on UHF, with negative modulation, FM sound etc. So all I needed was a bog-standard UHF modulator out of something. One of my dead Atari ST collection was duly raided and the modulator bodged onto my lash-up RGB+sync to monochrome composite converter.

Given everything that's wrong, the results aren't bad. And can be improved on.
  • TV frame linearity poor, won't adjust out with rear-panel height and frame linearity presets.
  • RGB+sync converter is terrible, need to make a better one (work is in progress on this.)
  • Cheating by using UHF - need to build VHF modulator.
  • Digital terrestrial card bought for this project was DOA - currently using analogue 'frame-grabber' card - analogue signal noisy, can't capture at decent resolution [1]
  • Font size for programme guide needs tweaking, it's unreadable.
  • MythTV user interface currently overscanned and needs tweaking.
[1]MythTV buffers live television (so you can pause and slow-motion etc.) When using a frame grabber card the software encodes grabbed frames to mpeg, writes this to disk, reads it off disk, then decodes it. Using a digital terrestrial card, the captured audio/video is already an mpeg stream so less processor power is needed - the encode stage is skipped, captured data is written to disk without processing. My experimental system (600MHz Pentium III) can only handle using a frame grabber card if I set the capture resolution to something like 240x240 and quality to "lousy"; once I have a working digital terrestrial card I can increase the resolution and quality somewhat.
Anyway, left to right, we have:
  1. MythTV programme guide.
  2. Off-air television.
  3. DVD playback.

Regards, Kat.
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Last edited by Kat Manton; 26th Mar 2006 at 11:17 am.
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Old 26th Mar 2006, 11:27 am   #2
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Default Re: 405-Line TV from PC - First Pictures!

sterling stuff Kat keep at it regards Den
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Old 26th Mar 2006, 11:47 am   #3
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Default Re: 405-Line TV from PC - First Pictures!

Excellent work Kat. You must be the first person to get any sort of 625-405 standards conversion working with a PC.

You certainly deserve a or two!
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Old 26th Mar 2006, 1:56 pm   #4
Sean Williams
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Default Re: 405-Line TV from PC - First Pictures!

Excellent stuff!

We are not worthy!

I bow to such wizardry!

Cheers
Sean
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Old 26th Mar 2006, 2:12 pm   #5
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Default Re: 405-Line TV from PC - First Pictures!

This is something which some people said could not be done. I knew it would, but like many others had no idea where to start!

If you would like another 405 TV for test purposes, let me know. There's also a few people working on recreated 405 Line Colour transmissions - this could be very handy!

By the way, Andy Emmerson once offered 50 for anyone who could do this. I don't know whether he's on here, but if not his E-Mail is expertise (at) sigtel.com

Praise to the expert - when is this going to be available?

Cheers and well done!

Steve P.
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Old 26th Mar 2006, 3:39 pm   #6
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Default Re: 405-Line TV from PC - First Pictures!

Well done Kat, I'm impressed.
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Old 26th Mar 2006, 4:52 pm   #7
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Default Re: 405-Line TV from PC - First Pictures!

Well done Kat!

I'm not particularly into the TV side of things - wireless and test equipment take up too much of my time.

I am tempted to get into it though if it means I can enjoy the Clangers

Regards,
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Old 26th Mar 2006, 5:09 pm   #8
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Default Re: 405-Line TV from PC - First Pictures!

This is quite cool IMHO. Ten times easier than programming the hardware as 'somebody else' suggested. *Ahem*

What more is there to say?

Frank N.
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Old 26th Mar 2006, 6:00 pm   #9
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Default Re: 405-Line TV from PC - First Pictures!

Quote:
Originally Posted by Kat Manton
[*]RGB+sync converter is terrible, need to make a better one (work is in progress on this.)
I take it that you have used something like standard resistor additions. One thing to consider is something like a clamp pulse to ensure the black level stays relatively constant.

Well done. The pictures look pretty good. Errr .......... Is that The Clangers I see on the last shot? I so loved them. They spoke my language
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Old 26th Mar 2006, 8:16 pm   #10
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Default Re: 405-Line TV from PC - First Pictures!

Let me also add my congratulations Kat - well done!!,... and dare I say that when I just mentioned to SHMBO your success in something that has eluded "us" for so long, her grin was sufficiently wide to signal an "I told you so" at 50 paces!

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Old 27th Mar 2006, 6:53 am   #11
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Default Re: 405-Line TV from PC - First Pictures!

Good morning Kat,
congrats to your first 405 pics.
I agree with Trish.

Kind regards
Darius
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Old 27th Mar 2006, 8:08 am   #12
Kat Manton
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Default Re: 405-Line TV from PC - First Pictures!

Hi,

Thanks all for the congratulations
Quote:
Originally Posted by Steve_P
If you would like another 405 TV for test purposes, let me know. There's also a few people working on recreated 405 Line Colour transmissions - this could be very handy!
I think I'd like to take you up on that offer (once I have a VHF modulator built), the Sony 9-90UB isn't exactly the cutting edge of 405-line technology, with AC-coupled video and no black-level clamping. Mine also seems to be having trouble with line and frame sync as well as the frame linearity problems noted (on 625-line off-air as well; it's not my electronics after all!) Another TV, or possibly a monitor, would prove very useful. (I used to have an ex-BBC Pye 2823C4Z 8.5" monitor many years ago, which suffered terminal LOPT failure and was scrapped, unfortunately. I still have the schematic for it and wouldn't mind another one.)

As for colour, well, the output of the PC is in colour to start with, so that shouldn't prove too difficult. It's on the list of things I'd like to investigate, along with getting it to do 441-line, 819-line and anything else I can think of. I'm not sure but I suspect an off-the-shelf NTSC encoder IC with a custom crystal might be all that's necessary for 405-line NTSC.

Quote:
Originally Posted by Trish
I take it that you have used something like standard resistor additions. One thing to consider is something like a clamp pulse to ensure the black level stays relatively constant.
The 'summing R, G and B' bit is correct, one fixed resistor and a couple more with series presets adjusted to the correct ratios with the aid of calculator and digital multimeter. There's an attempt at black-level clamping; though as noted it won't make any difference with the Sony TV anyway. The next versions will be DC coupled throughout, which saves additional circuitry just to put back something which was there originally. (The outputs of the graphics card are 0.7V p-p with black at 0V.)

Quote:
Originally Posted by Steve_P
when is this going to be available?
Plans are afoot behind the scenes to get an RGB+sync to mono composite converter sorted out which a) works better than my lash-up and b) minimises component count and so shouldn't cost much. As for the software, it's all already available - what I need to do is try to rationalise the installation and configuration process , investigate easier installation methods (such as the 'KnoppMyth' single-CD installer) then document the installation and configuration process step-by-step so it can all be installed assuming no prior experience of Linux. I ought to try to acquire some more graphics cards as well; at present I can only guarantee it working with my nVidia GeForce4 card as that's all it's been tested with. There's still more work to do, the problems with the overscanned user-interface and poor rendering of user-interface fonts need sorting out; as does getting it to work with a digital terrestrial card (I bought one but it arrived last week damaged and dead, I'm still awaiting a response from the supplier.)

Right, back to work... l;et's see if I can get the Sony TV working a bit better, it's not really showing off how good the output of the PC really is right now.

Regards, Kat
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Old 27th Mar 2006, 11:17 am   #13
Mike Phelan
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Default Re: 405-Line TV from PC - First Pictures!

The epithet "impressive" does not justify what you have done here, Kat!

Points to the West Yorks Team!!
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Old 29th Mar 2006, 7:16 pm   #14
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Default Re: 405-Line TV from PC - First Pictures!

It's very hard to put in to words what you have achieved here Kat, suffice to say that so many of us will owe you a great deal. Ever since 405 went off in 1986 I have heard people saying how a home computer should be able to do this, but nothing realistic has ever materialised.

I really do love the idea of being able to use my PC to directly feed out a 405 signal.

Thanks for doing such a superb job. It's totally beyond my understanding to even attempt to get my head around the maths alone!

All the best,

Peter.
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Old 29th Mar 2006, 9:05 pm   #15
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Default Re: 405-Line TV from PC - First Pictures!

Hi does this mean we could get a 405 line service working on line soon it would be worth the cost of broadband !. well done and keep up the good work. now where did i put that old 386 computer ok just kidding.
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Old 30th Mar 2006, 8:06 am   #16
Kat Manton
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Default Re: 405-Line TV from PC - First Pictures!

Hi,

I got the Sony TV working a little better - here's some more screenshots, I got streamed video off the 'net working as well
  1. Test Card C
  2. 'NASA TV' streamed off the Internet

Regards, Kat
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Old 30th Mar 2006, 8:42 am   #17
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Default Re: 405-Line TV from PC - First Pictures!

That's incredible Kat, so presumably this will allow any signal from the PC, being either originally PAL or NTSC to be converted to 405?

This will certainly make me upgrade to broadband!!

Incredible!!

Peter.
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Old 31st Mar 2006, 11:38 pm   #18
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Default Re: 405-Line TV from PC - First Pictures!

I could not follow before what was offered on this forum regarding the conversion of 625 to 405 lines where the costs of creating a cct/unit to show 625 lines on a 405 tv format were enormous due to the pioneer like costs and a small audience that perhaps two thirds of needed to save for, but were deterred and thought's were put on the back burner

However this pc format followed by interested parties is attracting and exciting forum members that may eventually be able to use a long sought after economical system that would create further interest from many enthusiasts present and temporarily absent, furthermore this potential breakthrough may save more vintage tv's that are discarded but may add significantly to the small number of Vintage TV people's interests present.

I am confident this will eventually be the outcome.

Vince.

Last edited by vince; 31st Mar 2006 at 11:49 pm.
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Old 1st Apr 2006, 8:31 am   #19
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Default Re: 405-Line TV from PC - First Pictures!

Amazing.

Although I have not had a chance to read through all the details yet of what Kat has done, I have a gut feeling that this is a very important landmark that will change our future 405 viewing for the better.
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Old 9th Apr 2006, 12:11 pm   #20
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Smile Re: Recording 405-line video on VHS

Hi folks
You do really need to go to the NVCF and see this......
I have just spent a very interesting half hour at Kat's Mission Control.
I have been watching "The Day of The Triffids" on a 405 monitor, courtesy a bit of PC software and not very much hardware.

Given that it was a small screen, and black-level restoration wasn't, it was stable, and the frequency counter sat rock solid as near to 10125 KHz (or should I say Kc/s?) as dammit - the small difference was purely because the sync clock is of course digitally generated.

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