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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 13th Jun 2020, 8:17 pm   #21
rambo1152
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Default Re: My 819 line French TV project

No crystals or custom PCB in mine Semir I'm afraid.
The PVC tape join hides the RGB sync matrix!

Actually, drift of the 51.75 & 48.25 MHz "Holme Moss" free-running carriers is not a problem.
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Old 13th Jun 2020, 9:19 pm   #22
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Default Re: My 819 line French TV project

Gosh Graham, and I thought that my construction was bad!

Peter
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Old 13th Jun 2020, 10:32 pm   #23
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Default Re: My 819 line French TV project

That's the problem when the initial proof-of-concept breadboard edition works so well, there is little impetus for improvement.

In my defence I did make a start on a slightly neater iteration over two years ago, but my only 405 line set has been poorly until recently, so I really should complete it now.

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I also need to write up grafting the LOPTX that David (FERNSEH) kindly sent me into the Cossor.

It's working fine; I just want to optimise the value of a tuning capacitor I found necessary, and mount the Tx in the original tin can.

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Old 14th Jun 2020, 4:08 pm   #24
Semir_DE
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Default Re: My 819 line French TV project

Dear all,

here I would like to share some images of my TVs with the ORTF test card that Jac kindly sent to me.

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This one needs some alignment, I know...

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In high resolution these images would show that the horizontal resolution of the TVs is limited to about 400 TVL while the vertical resolution is over 500 TVL. This is probably due to the fact that more recent 819 sets operated with a limited IF bandwidth e.g. the Radiola has roughly 6Mc and the small TV9-90 most likely even less. It would be interesting to see how the test card would look on an older French TV with the full IF bandwidth. On the other hand older sets may have worn out CRTs so resolution might be limited due to lack of focus in the CRT itself, but this is just an assumption on my side.

Cheers

Semir
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Old 14th Jun 2020, 5:00 pm   #25
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Default Re: My 819 line French TV project

Hi Semir,

My Philips TF651A indeed displays a somewhat better definition.
The modulator I used is MC44BS373 based and thus has a limited bandwidth.

Nevertheless, with this the TF651A can display 650 lines horizontal (819 vertical).
To the naked eye it looks better than I managed to catch in a photo.

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Due to influence from the magnetic field of the mains transformer, the picture wobbles a tiny bit, and this does not help for a sharp photo (and combine that with my very limited photographic capabilities )

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Old 14th Jun 2020, 6:10 pm   #26
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Default Re: My 819 line French TV project

Are these resolution bars square wave or sine?

Peter
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Old 14th Jun 2020, 6:35 pm   #27
Jac
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Default Re: My 819 line French TV project

Hi Peter,

The bars are square waves, but since the higher harmonics (of the narrower bars) will not pass through the system, this might not make much difference?

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Old 14th Jun 2020, 8:34 pm   #28
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Default Re: My 819 line French TV project

Hello Jac,

On your detail (second) picture if you look at the top where 350 is just truncated the lines look sharper than they do for the 350 in the centre left.

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Old 14th Jun 2020, 8:43 pm   #29
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Default Re: My 819 line French TV project

Hi Peter,

Yes they do. I think it has a lot to do with the contrast of the original:

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I must try the set with a better test pattern (like I sent to Semir).

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Old 14th Jun 2020, 9:05 pm   #30
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Default Re: My 819 line French TV project

Well that looks different but perhaps not in the screen shot with brightness reduced in the lower block.

Peter
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Old 15th Jun 2020, 6:29 pm   #31
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Default Re: My 819 line French TV project

Hi Peter,

I had another go at photographing the test card on the Philips TF651A.
(Due to my inadequate photographic skills and the wobble in the picture, it looks a bit better to the naked eye though.)

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Old 15th Jun 2020, 7:39 pm   #32
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Default Re: My 819 line French TV project

Hi Jac,

looks pretty good. Much better resolution than my Radiola TV. On your TV I'm sure you can probably read menus e.g. of VLC very clearly. That is a very nice vintage TV you have I just found this web site where yours is actually pictured.

My dream TV would be to get an E1 441 Line "Einheitsfernseher" but as only about 50 of them were ever built they are like gold dust and priced accordingly...

Cheers

Semir
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Old 15th Jun 2020, 7:56 pm   #33
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Default Re: My 819 line French TV project

Hi Semir,

Thanks.
The set I hope to add to my small collection would be a (any) pre-war Philips.
I must confess that an E1 is also on my wish list, but no chance of ever finding one in this country.

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Old 15th Jun 2020, 10:11 pm   #34
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Default Re: My 819 line French TV project

Hello Jac,

That does look good, especially in the close up.

Thanks,

Peter
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Old 16th Jun 2020, 1:31 am   #35
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Default Re: My 819 line French TV project

I'm curious that the test card image is for ORTF 2.
Did the second channel ever transmit in 819 lines ? I thought it was 625 only.
I'd be interested in knowing the early history of ORTF 2.
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Old 16th Jun 2020, 9:40 am   #36
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Default Re: My 819 line French TV project

In my previous post I was trying to relate Jac's 819 line bandwidth to a 405 line benchmark. The lower half of the image shows a crop of the TRF test card displayed on a 405 line receiver that has 3MHz bandwidth. (The 3MHz grating on Test Card C equates to something like 425 lines on the RTF test card.)

Jac's 819 receiver has better resolution than the 405 line receiver and the active part of the 405 line is 80.8uS whereas the active part of the 819 line is 41uS so Jac's receiver has bandwidth greater than twice the 3MHz of the 405 line receiver. ~7MHz.

Peter
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Old 16th Jun 2020, 9:56 am   #37
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Default Re: My 819 line French TV project

Quote:
Originally Posted by red-duck View Post
I'm curious that the test card image is for ORTF 2.
Did the second channel ever transmit in 819 lines ? I thought it was 625 only.
I'd be interested in knowing the early history of ORTF 2.
As far as I know it was 625 lines from the start, which I presume was system L without the SECAM encoding at first.
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Old 20th Jun 2020, 10:34 pm   #38
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Default Re: My 819 line French TV project

Dear all,

I would like to share some more findings here regarding the implementation of an 819/576/405 signal generation system on a Linux PC in the hope some of you might find this useful. My first experiments were with two laptop computers an HP 8440p and an even older Dell Latitude 6400

Both employ the Intel integrated GMA graphics solution which seems to be limited when it comes to clock rates below 20Mc. While this is not a limitation for higher resolution output formats it will limit possibilities for outputting low res formats like PAL (576i) or 405i. Sine the french 819i format requires a clock close to 30Mc this format could be generated with ease on both laptop PCs. I was unable, however, to get a PAL or 405 output to work on those PCs.

Since I was aiming for a solution that could be switched to 405i, 576i and 819i I decided to conduct some more experiments. A few considerations had to be made for the whole system to work well with all desired formats:

1) The output of the TV signal should be over a VGA connector and this should be a second head on the PC. This meant a graphics card with both DVI/HDMI and ananlog VGA outputs needed to be found.

2) The main or primary monitor should have a decent resolution e.g. 1280x1024 or higher, so all OS menus, VLC player etc. could be run in a normal fashion

3) It should be easy to switch resolutions for the secondary monitor without a reboot and without interrupting playback of a video. This is to be able to demonstrate the different formats while playing the same video file.

4) The PC should be powerful enough to play HD content since only HD content could be down scaled to 819i while SD content would be up scaled thus not using the full potential of the 819i format. For a 405i only system a much less powerful PC would suffice as only SD content would need to be playable.

The problem, or so I thought, was to find a suitable graphics adapter that could be configured to output all desired formats while at the same time having an interface that was compatible with a modern PC motherboard. As I had read here that old GeForce 4 graphics cards were a suitable choice I tried an old GeForce 6600 with AGP interface. I still had this as well as the quite dated PC with a Pentium 4 processor. The results with the GeForce 6600 were disappointing. It worked with 405i but on 819i it produced a second vertical sync pulse halfway across the picture. Since the old Pentium 4 PC was not an ideal choice for playing HD content anyway I decided to investigate a more modern PC architecture.

I also had an old small PC that I had built a few years ago with an Asus N4L-VM Motherboard and an Intel core2duo this has a PCI-Express 16 interface which makes the choice of graphics card much easier. Also not the most recent technology but just powerful enough to play HD content as long as a good graphics adapter was used.

Originally this had an ATi Radeon 4000 (EAH4350) in it which worked well under Windows 8 as an HTPC. When I installed Linux Mint XFCE 32 Bit on this machine it also worked well for the OS and I could get modelines to work for 405i. It would not work with 819i, however, in this case the sync of every second field was inverted and no matter which setting I chose in the modeline this issue remained. Back to the drawing board...

As a next test I extracted an Nvidia N210 card made by MSI from another machine I had and put it into the one I was testing. This was the answer! All modes were supported immediately and I could switch between formats even while playing a video in full screen on the second "monitor" i.e. VGA output to my modulator. All this worked until I decided as suggested by the Linux OS driver manager to install the proprietary Nvidia drivers. After doing so the modelines no longer worked, so be warned only use the integrated Xorg drivers...

As a third choice I had ordered or more recent Nvidia N710 card made by Zotac. This costs around 35 and is very sleek and does not need a noisy fan. This card also works perfectly with all modes. Here is an image of the card which can still be bought online:

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So as a conclusion from this non representative test it seems that Nvidia cards even of newer design work with all modes we need for generating 405i, 576i and 819i. Summary:

Intel integrated graphics: good for 819i not good for 405i (576i was not tested)
ATi Radeon EAH4350 (Radeon 4000 series): good for 405i, not Good for 819i (576i was not tested)
Nvidia N210 made by MSI: good for all modes 405i, 576i and 819i
Nvidia N710 made by Zotac: good for all modes 405i, 576i and 819i

Here are a few images of the settings:

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for a 405i output

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for a 819i output



A few hints for setting up VLC:

- I used the detached video interface setting, so the window containing the play list will remain on the PC screen while only the full screen video can be moved to the secondary monitor. This will allow adding new clips to the play list while playback is ongoing

- It is a good idea to select a fixed video output renderer instead of "auto" in the VLC video settings. If this is not done the VLC interface will initialize every time it starts playing a clip and this will move the full screen video back to the PC screen.

Finally an image of the PC in its case:

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I hope this information will be useful to others here while experimenting with modeline signal generation.

Cheers

Semir
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Old 21st Jun 2020, 6:33 pm   #39
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Default Re: My 819 line French TV project

I'm using an ATI Radeon HD 2400 and the fan is rather noisy so it's interesting that the Nvidia N710 works well without a fan. I thought there was some incompatibility between Nvidia cards and Jeroni Paul's Modeline program?

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Old 22nd Jun 2020, 9:27 pm   #40
Semir_DE
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Default Re: My 819 line French TV project

Hi Peter,

I did not use the "Winmodelines" program as such, just the posted modelines and the ones made by Kat Manton. These worked without any issues. I also use Linux not Windows, so the incompatibility described on Jeroni Pauls page plays no role.

I'll post the modelines I used here later when I'm on my other pc...
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