Narrow-Bandwidth Television Association

I found a book "das Fernsehen" by Kurt Hipfert from 1938 on a radio fair. In this book are some very interesting pictures, I think most of them are not known outside Germany. I start here with some tests made in 1935 by the "Reichspost" as the leading public TV experimentator in Germany. The pictures are in resolutions of 30, 48, 60, 90 and 180 lines, all standards used in Germany between 1929 and 1935 (when the official TV-service started in Germany, with 180 lines. (Knowing that in England and USA were experiments with more than 240 lines, but Germany wanted to be the first...)). As you can see, the Nipkow-disc was still in use for the 180 line picture, you can see the bows in the picture.

I wonder what the hole diameters were for the higher resolution discs?

And how they actually mechanically manufactured them?


Regards,


Graham

For the 180 line pictures they used a disc with 4 apertures per frame, and a second disc which covers the currently not needed 3 holes. So the disc could stay smaller, but have to run 4 times as fast, at 25 frames per second it ran at 6000 rpm. This system was in use until 1938, even with the 441 lines! They used up to 4 rotating masks. The scanner at the second picture is a flying spot scanner, which was in use until 1938 in Germany! (For studio, they had a "Farnsworth camera" for outside pictures, too. There is a good documentary available "Television under the swastica". It is available in english. The film is of course about Nazi propaganda, but it gives a good insight about the used technic, too.

Thanks for the technical information, Dr.Z.

Very impressive engineering!


Kind regards,


Graham

Thanks for sharing those images at various lines.
The boat is really not recognisable as such until the 60 line picture.

One could so devise a quiz using 32 lines, "Spot what this is?"
Offer a prize at the next NBTVA convention where a 32 line machine shows many images of common objects and visitors have to list what they are.. The one getting the most correct gets the prize....
Albert.

Thanks for posting these pictures, Volker. I have never seen such a direct comparison of such a range of resolution of television images scanned by optical means.

As Albert has pointed out, a general landscape image of even 48 lines of resolution is difficult to recognise, at least in still form. The 60 line image is a distinct improvement and the 90 line image is excellent. In fact, to my eyes there is less improvement between 90 line and 180 line images than there is between any of the others.

Thank You For The Pictures.
Did the article state if the picture used was a still image, telecine or the intermediate process ?
Also off the NBTV subject, did it name the ship ?

Regards
Phil

I found nothing about the ship, the only remark in this book is "Foto: Deutsche Reichspost". But looking in another, newer book "Der Traum vom Sehen" which was printed 10 years ago for an exhibition about TV I found the following pictures, which I mentioned earlier from the short film "Wochenende", produced in 1929 for the experimental TV. (The two women are Schura von Finkelstein and Imogen Orkutt, working for the Reichspost in that time.) The screenshots are later, of course. I think they've made at the same time as the pictures of the ship. In that book, "Traum vom Sehen", both series are printed together.

I think that the above pix demonstrate that probably the minimum line rate for a watchable image is around 60 lines.

I can confirm that (for a still image) double interlaced 32 line NBTV pictures (ie 64 lines) yield a vastly improved result compared to the non-interlaced 32 line version.

Text legibility is very much improved. Pity when the image moves though!

GL

AncientBrit wrote:I think that the above pix demonstrate that probably the minimum line rate for a watchable image is around 60 lines.GL

I agree that anything beyond a head-and-shoulders view needs 60 lines. A 60 by 60 pixel image at 12.5 fps would just fit within a high fidelity audio channel, so this would be an interesting NBTV project.

Experimenting with "the Big picture" and "Avi2NBTV" shows that adding colour is a massive improvement. And what we can see here, on our own televisors, our 32 line pictures are looking better and much more detailed than the old pictures, doesn't matter if you take old German pictures or from the Baird system. (In fact the systems were not so different, Baird was a shareholder of the "Fernseh A.G.") There are two problems: Dark pictures on early TVs and less advanced photography in those days.