Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Television is 100 years old today

diamondgeezer.blogspot.com

Post reply on HN
Print view View original

171–180 of 283 posts

Re: Television is 100 years old today

#171

Post by lebuffon »

ninkendo wrote: post #155
retrac wrote: post #128

Earlier quoted context omitted.

There's a synchronous and instantaneous nature you don't find in modern designs. The image is not stored at any point. The receiver and the transmitter are part of the same electric circuit in a certain sense. It's a virtual circuit but the entire thing - transmitter and receiving unit alike - are oscillating in unison driven by a single clock. The image is never entirely realized as a complete thing, either. While s…

It doesn’t begin at the transmitter either, in the earliest days even the camera was essentially part of the same circuit. Yes, the concept of filming a show and showing the film over the air existed eventually, but before that (and even after that, for live programming) the camera would scan the subject image (actors, etc) line-by-line and down a wire to the transmitter which would send it straight to your TV and in…

Our station had an art department that used a hot press to create text boards that were set on an easel that had a camera pointed at it. By using a black background with white text you could merge the text camera with a camera in the studio and "super-imposed the text into the video feed.

"And if you tell the kids that today, they won't believe it!"

Re: Television is 100 years old today

#172

Post by iberator »

torginus wrote: post #146
retrac wrote: post #128

Earlier quoted context omitted.

There's a synchronous and instantaneous nature you don't find in modern designs. The image is not stored at any point. The receiver and the transmitter are part of the same electric circuit in a certain sense. It's a virtual circuit but the entire thing - transmitter and receiving unit alike - are oscillating in unison driven by a single clock. The image is never entirely realized as a complete thing, either. While s…

Yeah it super weird that while we struggle with latency in the digital world, storing anything for any amount of time is an almost impossible challenge in the analog world.

You should check out:

- Core memory - Drum memory - Bubble memory - Mercury delay line memory - Magnetic type memory :P

And probably many more. Remember that computers don't even need to be digital!

Re: Television is 100 years old today

#173

Post by avadodin »

jasonfarnon wrote: post #164
avadodin wrote: post #157

Earlier quoted context omitted.

The memories are probably nothing like how they were at the time, but I vividly remember running away from my parents with my elder sister, getting bullied by an extremely blond girl at day care, and falling and literally eating dirt including that it was salty around 2-3.

But at some point don't you lose the direct memory, and only retain remembering it? Eg I don't know that I directly remember the fight I got in with the neighbor kid at age 4, but I can definitely remember thinking about it for a something we had to write in school around age 8. Or at least I could when I was in high school. That's when I thought about the time I had to write that essay when I was 8. At some point al…

At some point, most memories are like that, to be honest – not just early childhood ones. You could say I consider these are "vivid" because I can recall more details of them than of the average memory.

Re: Television is 100 years old today

#174

Post by tzs »

I've sometimes wondered how things would have been different if the TV pioneers had went with circular CRTs instead of rounded rectangles.

Circles would have had a couple of advantages. First, I believe they would have been easier to make. From what I've read rectangles have more stress at the corners. Rounding the corners reduces that but it is still more than circles have. With circles they could have more easily made bigger CRTs.

Second, there is no aspect ratio thus avoiding the whole problem of picking an aspect ratio.

Electronically the signals to the XY deflectors to scan a spiral out from the center (or in from the edge if you prefer) on a circle are as easy to make as the signals to to scan in horizontal lines on a rectangle.

As far as I can tell that would have been fine up until we got computers and wanted to use TV CRTs as computer displays. I can't imagine how to build a bitmapped interface for such a CRT that would not be a complete nightmare to deal with.

Re: Television is 100 years old today

#175

Post by lebuffon »

iso1631 wrote: post #26
MoonWalk wrote: post #16

Earlier quoted context omitted.

You should read about the invention of color television. There were two competing methods, one of which depended on a spinning wheel with colored filters in it. If I remember correctly, you needed something like a 10-foot wheel to have a 27-inch TV. Sure enough, this was the system selected as the winner by the U.S. standard-setting body at the time. Needless to say, it failed and was replaced by what we ended up wit…

Originally you had 30fps, it was the addition of colour with the NTSC system that dropped it to 30000/1001fps. That wasn't a decision taken lightly -- it was a consequence of retrofitting colour onto a black and white system while maintaining backward compatibility. When the UK (and Europe) went colour it changed to a whole new system and didn't have to worry too much about backward compatibility. It had a higher ban…

An engineer at RCA in New Jersey told me that at the first(early) NTSC color demo the interference was corrected by hand tweaking the color sub-carrier oscillator from which vertical and horizontal intervals were derived and the final result was what we got.

The interference was caused when the spectrum of the color sub-carrier over-lapped the spectrum of the horizontal interval in the broadcast signal. Tweaking the frequencies allowed the two spectra to interleave in the frequency domain.

Re: Television is 100 years old today

#176

Post by charcircuit »

pinnochio wrote: post #72
sosomoxie wrote: post #64

CRTs are peak steam punk technology. Analog, electric, kinda dangerous. Just totally mindblowing that we had these things in our living rooms shooting electric beams everywhere. I doubt it's environmentally friendly at all, but I'd love to see some new CRTs being made.

We're getting awfully close to recreating CRT qualities with modern display panels. A curved 4:3 1000Hz OLED panel behind glass, and an integrated RetroTink 4K with G-Sync Pulsar support would do it. Then add in a simulated degauss effect and electrical whine and buzzing sounds for fun.

>1000 Hz

This sounds like a brute force solution over just having the display controller read the image as it is being sent and emulating the phosphors.

Re: Television is 100 years old today

#177

Post by [deleted] »

jedberg wrote: post #2

This is interesting. John Logie Baird did in fact demonstrate something that looked like TV, but the technology was a dead end. Philo Farnsworth demonstrated a competing technology a few years later, but every TV today is based on his technology. So, who actually invented Television?

[deleted]

Re: Television is 100 years old today

#178

Post by leguminous »

accounting2026 wrote: post #149
retrac wrote: post #128

Earlier quoted context omitted.

There's a synchronous and instantaneous nature you don't find in modern designs. The image is not stored at any point. The receiver and the transmitter are part of the same electric circuit in a certain sense. It's a virtual circuit but the entire thing - transmitter and receiving unit alike - are oscillating in unison driven by a single clock. The image is never entirely realized as a complete thing, either. While s…

> The image is not stored at any point. Just wanted to add one thing, not as a correction but just because I learned it recently and find it fascinating. PAL televisions (the color TV standard in Europe) actually do store one full horizontal scanline at a time, before any of it is drawn on the screen. This is due to a clever encoding used in this format where the TV actually needs to average two successive scan lines…

At some point, most NTSC TVs had delay lines, too. A comb filter was commonly used for separating the chroma from the luma, taking advantage of the chroma phase being flipped each line. Sophisticated comb filters would have multiple delay lines and logic to adaptively decide which to use. Some even delayed a whole field or frame, so you could say that in this case one or more frames were stored in the TV.

https://www.extron.com/article/ntscdb3

Re: Television is 100 years old today

#179

Post by rhplus »

tzs wrote: post #174

I've sometimes wondered how things would have been different if the TV pioneers had went with circular CRTs instead of rounded rectangles. Circles would have had a couple of advantages. First, I believe they would have been easier to make. From what I've read rectangles have more stress at the corners. Rounding the corners reduces that but it is still more than circles have. With circles they could have more easily m…

I would guess that even at the time a circular viewport would have seemed a bit weird and so rectangular was preferred. After all, theater stages, most windows, photographs and books - all common place - aren’t circular either.
Post reply on HN