120 and 180 line viewing

Forum for discussion of electronic television. Generally, stuff to do with CRTs and not using mechanical displays.

Re: 120 and 180 line viewing

Postby murphyv310 » Mon Sep 21, 2020 8:50 am

Hi.
It's a long time since I posted on this thread.
2018 wasn't a good year as my wife had a hysterectomy in the January then later in the year took ill again. Sadly she passed away in January 2019.
Life then was empty.
I kind of gave up with many things, I was given some sets and stuff from friends to keep me occupied. This didn't help and I turned to prayer. Fortunately things improved for me later on and I met a good lady from Kenya and a good Christian. I have since remarried and am happy. I'm doing more in the hobby now too so I hope to one day contribute here once again.
Cheers Trevor.
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Re: 120 and 180 line viewing

Postby Steve Anderson » Mon Sep 21, 2020 1:13 pm

Hello Trevor,

We're sorry to hear of the disastrous two years for you, but it seems things are on the improve.

We look forward to your contribution as and when you can.

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Re: 120 and 180 line viewing

Postby GrantXTV » Mon Aug 08, 2022 6:55 am

Hi,

I have been experimenting with the 60 line system and I am now looking for a way to get a video signal for the 120 line format as the World Converter WC-01 is no longer available. What are my options? is there a universal software standards converter out there that I can use?

I am looking for a R-Y, B-Y and Y output video signals to work with, or do I need design my standards convert to do this job?
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Re: 120 and 180 line viewing

Postby Steve Anderson » Mon Aug 08, 2022 11:43 am

GrantXTV wrote:...or do I need design my standards convert to do this job?

Considering the options you have, I suspect this is going to be the outcome. The YUV matrixing is comparatively easy. If you keep it YUV and not composite (PAL/NTSC) there's little difference from monochrome.

Having done a full 625 monochrome SPG (Sync Pulse Generator) for 625/50 in a PIC micro this should be a little bit easier. Though many might choose the Arduino/R-Pi route instead.

It was a standards convertor 'of sorts', but not on this scale. (It was SSTV-625).

The problem with a device like this is it isn't really commercially viable. The returns on time and resources required and the projected sales don't justify the outlay. The WC-01 and the like must have been a labour of love. I have looked into this thoroughly in the past with a view to doing something similar. My conclusion - don't bother.

There are exceptions where the application has a wide appeal, an example is here...I wish I thought of it...

https://www.dos4ever.com/uTracer3/uTracer3_pag0.html

...and also...though 'on hold' at the moment....

https://oscilloclock.com/

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Re: 120 and 180 line viewing

Postby Steve Anderson » Mon Aug 08, 2022 2:16 pm

Continuing on from above....

There are two 120-line standards listed for the WC-01 in the manual, and two 180-line standards.

120/25p 4:3 progressive mechanical (TeKaDe/Fernseh-A.G., 1932)
120/24p 6:5 progressive electronic hybrid (RCA U.S.A. experimental, 1931-1932)

180/25p 6:5 progressive electronic (TeKaDe/Fernseh-A.G., 1934-1939)
180/24p 6:5 progressive electronic hybrid (RCA U.S.A. experimental, 1932)

Which one(s) interest you? My choice would be the first, though electronic, 120/25p 4:3. This would be a comparatively easy (but not trivial) conversion from 625/50i, colour would add some complexity, even handling the signals entirely in YUV....aka 'Component'.

The version of the WC-01 manual I have is Revision 2.0, 26 August, 2010. Were there any later ones?

Steve A.

While on this subject, the 240/25p 4:3 progressive electronic hybrid (Baird, U.K., 1936) interests me too, though none of these modes can hardly be called 'Narrow Bandwidth'!
My choices are biased toward 25Hz as I live in a 50Hz country so any sources here are locked-in to those figures.
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Re: 120 and 180 line viewing

Postby Harry Dalek » Mon Aug 08, 2022 10:09 pm

Baird Television developed a 180-line system also be vertical scanning i would think but looking into it wrong he went horizontal ~ !
Baird Company at their Crystal Palace studio in 1934, mechanical telecine that produced them. Both are reproduced frames of Madeline Carroll appearing in the last reel of the film "I WAS A SPY" (released by Gaumont-British)
One of the few TV systems on the mode line program and PC video card systems converter that's not working yet not for me any way .
https://archive.brainsys.com/Index/syde ... rd_02.html
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: 120 and 180 line viewing

Postby GrantXTV » Mon Aug 08, 2022 11:20 pm

Hi Steve,

The main limitation is the 192 kHz sound device within my PC, providing for a maximum output frequency of 96 kHz, with the 60 line system I am using a 48 kHz USB sound device. The main issue is a very poor DC response, so have built a DC clamp circuit which has helped, this is why I am putting to together a home made USB ADC board for video.

The aim is to RF modulate NBTV multiplexed transmission using QAM, I have a modulator design that will do this, but I will need to add in a video processing stage. Therefore I have been using sequential memory colour, that flips on the odd and even lines. With 12.5 frame rate, currently at 60 lines and the sound is encode into a second QAM carrier alongside the vision carrier. Going to 120 lines will be much the same approach staying with the same colour format and frame rate, with main limitation been 96 kHz maximum usable frequency.

If I can not find a hardware scan converter, I will look for a software that is like what I am using for the 60 line system, that would convert into 192 kHz wav file for the higher number of lines, It going be a five year project, as it seems I will be developed all the hardware and the software as I go.

Grant
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Re: 120 and 180 line viewing

Postby Steve Anderson » Tue Aug 09, 2022 3:42 pm

Hmm, you're going for more exotic techniques than I would even consider! Good luck! Though I have have used QAM within a project in Singapore a few years ago, that was 'real work' though.

What is going to be your source standard? i.e. what are you converting from?

Steve A.

QAM = Quadrature Amplitude Modulation. Google it.
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Re: 120 and 180 line viewing

Postby Harry Dalek » Tue Aug 09, 2022 10:05 pm

Well the answer is give up on the sound device and swap to a video card it has been tested from 107 line to over 800 line its a no brainer ,sound device to a video device all the bandwidth you could want.
120 line
result out of video card 2.677khz 25hz
Modeline "1500x100_25 3.0kHz" 8.840 1500 2828 2938 2948 100 105 110 120 -hsync -vsync
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: 120 and 180 line viewing

Postby GrantXTV » Tue Aug 09, 2022 11:29 pm

Yes, I have tested a wide range of modulation systems, whereby QAM has the highest spectrum efficiency, making possible send both colour and video information together within a single RF carrier.

"What is going to be your source standard?" I plan to do the first step of conversion within VLC, this will provide for a wide range of input formats, on the output side it all comes down to the maximum bandwidth I have got to use. As I plan to do on air testing using Sky-wave propagation on HF, so far I am thinking of two formats 60 and 120 lines (60 x 72 x 12.5 and 120 x 144 x 12.5). I am also working on a few ideas for analog video compression that will minimize the overall RF bandwidth, as we now have a lot of technology today that was not possible 100 years ago.

As for using a video card, the lowest setting for VGA is 200 x 320 that was used with DOS in the 1990's, the other video card I use is the PVR-350 that outputs PAL, NTSC and SECAM as a fixed size.

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Re: 120 and 180 line viewing

Postby Harry Dalek » Wed Aug 10, 2022 4:14 pm

GrantXTV wrote:.

As for using a video card, the lowest setting for VGA is 200 x 320 that was used with DOS in the 1990's, the other video card I use is the PVR-350 that outputs PAL, NTSC and SECAM as a fixed size.

Grant


Yes a standard video PC video card !,plug in the one i and many others are using with the modeline program you will forget about the sound card for this work ,its fine for 60 and below ! but an old gaming card that's pretty cheap these days mine was 30 bucks can do the the lot for the higher line rates and frame rates ,i don't think it can go below 107 line but i have never tried yet adjust settings in mode line or making my own .
what works on mine at the moment
405 10.12khz 50hz
240 12.82khz 53.44 hz
441 11.04khz 50hz
625 15.65khz 50hz
525 15.70khz 59.79hz
625 1500x580........15.60khz 49.92hz
107 2.674khz 25hz
819 20.52khz 25hz
120 2.677khz 25hz
mainly to do with 405 line but does not have to be
viewtopic.php?f=15&t=3143
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Re: 120 and 180 line viewing

Postby GrantXTV » Wed Aug 10, 2022 10:05 pm

Hi Harry,

Yes, I am sure your solution will work, but I am using Ubuntu Linux on a laptop, so I will need to pickup a USB to VGA adapter and see if I can change the video setting on it.

I also went through the numbers last night to see what was possible with 480 x 640 VGA, if I started at 75 fps with 24 bit colour I would get these formats:
( 480 / 4 ) x ( 640 / 4 ) x ( 75 / 6 ) = 120 x 160 x 12.5
( 480 / 8 ) x ( 640 / 8 ) x ( 75 / 6 ) = 60 x 80 x 12.5

So I could make a very basic standards converter with ADC's, DAC's, Static RAM's, FPGA, PLL and a USB interface, without too much work involved and this all from a fixed VGA of 480 x 640 x 75. Next step would be to buy a USB to VGA adapter and see how far I can push it below the standard VGA, as there is terminal settings that I can set from within Linux to do this. After which I could wright a Linux application that would have these profiles ready to go on the transmitter end, using my current ADC to USB hardware to receive the video signal.
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Re: 120 and 180 line viewing

Postby Steve Anderson » Thu Aug 11, 2022 1:24 pm

GrantXTV wrote:...I am using Ubuntu Linux

...likewise, but I would think unless a Windoze version is developed the uptake will be minimal. Such is the way of Lemmings.

However, as in my case I'm avoiding any direct PC application in this so it's not an issue. I prefer that whatever I build is not reliant on a PC....as useful as they may be....

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Re: 120 and 180 line viewing

Postby GrantXTV » Thu Aug 11, 2022 2:13 pm

Hi Steve,

Hardware and software both have a place in a lot of my projects, such as using FPGA's over fixed logic gates say in the 74HC range for example. It is all about the process of getting a electronic project to work is the important part and trying out new ideas in the design as you go.

The VGA approach is something I would not have done, but saying that it is a far better way to generate a video signals than working with wav files. Therefore I have ordered a USB to VGA converter in today for my laptop, it should be usable within Ubuntu and it would not take too much to build a hardware converter to take the VGA down to a wide range of NBTV formats. As I am working it out as I go, I have needed to rework my PCB layout three times so far, as I keep coming up with new ideas on how this would all go together.
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Re: 120 and 180 line viewing

Postby Steve Anderson » Thu Aug 11, 2022 3:04 pm

GrantXTV wrote:...I keep coming up with new ideas on how this would all go together.

Design is an iterative process, with each step you hopefully get closer to the desired objective. Witness my own efforts r.e. SSTV demodulation..

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