How photos were transmitted by wire in the 1930s • Hacker News Board

Re: How photos were transmitted by wire in the 1930s

#51

Post by roywiggins » Wed, Mar 13, 2024, 9:22 PM UTC

rightbyte wrote: post #4

In it's simplicity it is genius. I had no clue this was a thing. https://en.m.wikipedia.org/wiki/Wirephoto I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message.

Possibly the high water mark of such things was the "Secret Life Of Machines" series. Here is their episode on fax machines:

https://www.youtube.com/watch?v=yuUyt9RG7pk

Re: How photos were transmitted by wire in the 1930s

#52

Post by roywiggins » Wed, Mar 13, 2024, 9:24 PM UTC

jimbokun wrote: post #44

mhuffman wrote: post #8

Earlier quoted context omitted.

>I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message. I wonder what happened? I have been blown away by some of the older explainer videos from the 40s and 50s, esp. some of the military training videos for vehicle repair, electrical engineering, etc. Very concise and very clear explanations, always with visua…

Those videos were the equivalent of 3brown1blue for their day. With YouTube, there are far more videos of this sort today than there were then.

Yes, however, nobody has (imho) done it better than The Secret Life of Machines did it back in the late 80s/early 90s:

https://www.youtube.com/watch?v=yuUyt9RG7pk

Re: How photos were transmitted by wire in the 1930s

#53

Post by petee » Wed, Mar 13, 2024, 9:34 PM UTC

A neat variation from the era is Hellschreiber teleprinter, graphically prints the characters using a spinning head that impacts the tape strip, which results in readable messages even with heavy interference

https://en.m.wikipedia.org/wiki/Hellschreiber

Edit: some ham radio operators still use it for fun, and I'd heard that one of the SDR decoders can read it

Re: How photos were transmitted by wire in the 1930s

#54

Post by jnewkirk » Wed, Mar 13, 2024, 9:48 PM UTC

Animats wrote: post #28

rightbyte wrote: post #4

In it's simplicity it is genius. I had no clue this was a thing. https://en.m.wikipedia.org/wiki/Wirephoto I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message.

The hard part was synchronization. We're used to synchronization being easy today, but it was really hard to synchronize anything until the 1980s, when phase-locked loops became easy and cheap.

I had a pair of these transceivers when I was in my teens, from a somewhat later period, thanks to my grandfather who refurbished them from his time as a telegrapher at Western Union. Synchronization at startup took ten seconds or so while each unit adjusted its timing and apparently sent a correction signal to the other, drums whirling all the time and gradually matching initial positions. It looked like the most primitive process possible, but worked every time.

Re: How photos were transmitted by wire in the 1930s

#55

Post by Gerard0 » Wed, Mar 13, 2024, 10:02 PM UTC

cm2187 wrote: post #43

mhuffman wrote: post #8

Earlier quoted context omitted.

>I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message. I wonder what happened? I have been blown away by some of the older explainer videos from the 40s and 50s, esp. some of the military training videos for vehicle repair, electrical engineering, etc. Very concise and very clear explanations, always with visua…

Youtube is full of videos like that. A few sample excellent channels: https://www.youtube.com/@animagraffs https://www.youtube.com/@engineerguyvideo https://www.youtube.com/@Lesics/videos The problem is more that they are drowned under the volume of content available.

Wow, thanks for sharing!

Re: How photos were transmitted by wire in the 1930s

#56

Post by barrkel » Wed, Mar 13, 2024, 10:02 PM UTC

Animats wrote: post #28

rightbyte wrote: post #4

In it's simplicity it is genius. I had no clue this was a thing. https://en.m.wikipedia.org/wiki/Wirephoto I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message.

The hard part was synchronization. We're used to synchronization being easy today, but it was really hard to synchronize anything until the 1980s, when phase-locked loops became easy and cheap.

Yes, I was looking for the bit where they addressed skew. You can even see it in the demo with the string, horizontal lines come out wavy after transfer to the other spool due to small differences in synchronization.

Re: How photos were transmitted by wire in the 1930s

#57

Post by barrkel » Wed, Mar 13, 2024, 10:04 PM UTC

rightbyte wrote: post #33

Animats wrote: post #28

Earlier quoted context omitted.

The hard part was synchronization. We're used to synchronization being easy today, but it was really hard to synchronize anything until the 1980s, when phase-locked loops became easy and cheap.

Does the belinograph need syncing though? I imagine you would just have a waste ribbon around the photo and start it after the call with say a delay you both agreed too. Or maybe you could send light in some known pattern with a starter strip and the receiver could look at the lamp. Attenuation most have been a problem though? I guess you could send some sort of calibration photo to adjust gain? I don't think practic…

You need to synchronize the spin rate of the drums on either end. If there's a difference of half a rotation over however many hundreds (thousands?) of rotations to transmit the photo, you'd end up with a completely distorted picture.

Re: How photos were transmitted by wire in the 1930s

#58

Post by xandrius » Wed, Mar 13, 2024, 10:08 PM UTC

ClassyJacket wrote: post #50

mhuffman wrote: post #8

Earlier quoted context omitted.

>I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message. I wonder what happened? I have been blown away by some of the older explainer videos from the 40s and 50s, esp. some of the military training videos for vehicle repair, electrical engineering, etc. Very concise and very clear explanations, always with visua…

Have you seen Technology Connections on YouTube?

Yeah, a bit dry and it doesn't always hit the spot with the tone.

I wanted to like it but couldn't.

Re: How photos were transmitted by wire in the 1930s

#59

Post by drmpeg » Wed, Mar 13, 2024, 10:11 PM UTC

petee wrote: post #53

A neat variation from the era is Hellschreiber teleprinter, graphically prints the characters using a spinning head that impacts the tape strip, which results in readable messages even with heavy interference https://en.m.wikipedia.org/wiki/Hellschreiber Edit: some ham radio operators still use it for fun, and I'd heard that one of the SDR decoders can read it

With SDR, you can paint an image into the receiver waterfall with OFDM.

https://www.youtube.com/watch?v=saac0ZtTeX4 (be sure to switch to 1080p)

https://github.com/drmpeg/gr-paint

Re: How photos were transmitted by wire in the 1930s

#60

Post by chiph » Wed, Mar 13, 2024, 10:26 PM UTC

mhuffman wrote: post #8

rightbyte wrote: post #4

In it's simplicity it is genius. I had no clue this was a thing. https://en.m.wikipedia.org/wiki/Wirephoto I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message.

>I really like these old "explaining" films. The pedagogical level is far higher than what seems common today. And the they take their time to convey the message. I wonder what happened? I have been blown away by some of the older explainer videos from the 40s and 50s, esp. some of the military training videos for vehicle repair, electrical engineering, etc. Very concise and very clear explanations, always with visua…

It's simple, yet hard to execute well. Each sentence contains one piece of information to be imparted. The speed of speaking is slower - with emphasis on diction and pronunciation. There is a slight pause between sentences to allow the recipient time to comprehend what was just said.

Try it yourself - read some of the comments here in that manner and observe the difference.