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TheGreenGoblin
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Re: Televisions

#41 Post by TheGreenGoblin » Sun Dec 08, 2019 4:33 am

The PAL versus NSTSC standards and never the twain would meet or work together without jiggery pokery. With PAL's 625 lines giving better definition than the NSTSC's 525 lines although the US frame refresh rate at 60 Hertz (based upon the US mains clock rate versus the 50 cycles in UK, Europe etc.) was higher. The different frame refresh rates could be seen as a flickering screen if a NSTCS formatted TV film was shown on a PAL screen. The asynshronicity and different aspect sizes being fixed by the insertion of dark bands into the NSTSC formatted films (top and bottom of the frames).

The PAL system was visually better due to the higher definition.

Nerd alert - Talking of frames and the 50 Hertz screen refresh in the UK, did anybody here ever use the 20 KB frame buffer on the BBC micro (or the Acorn graphics shadow buffer) to store a sneakily contrived 6502 assembler program that could be run on the TV frame refresh sync cycle where one could run the code to give the appearance of multitasking. My cup of joy raneth over when I got an on screen clock to appear and run on the screen in the bottom right hand corner (like you take for granted in Windows and so on) while running another program. No flicker and smooth as a baby's bottom giving perfect time, all using the frame interrupt event.

Small things and small minds I guess!
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Re: Televisions

#42 Post by Hydromet » Sun Dec 08, 2019 5:47 am

First TV I saw was built by a schoolmate's father in 1955, prior to the arrival of transmissions in 1956. It had a circular CRT, and I don't think he had a camera - never saw it operating. Not long after, I went with my father to the old Museum of Science & Technology in Sydney, where they had installed a colour closed circuit system. We thought it was amazing.

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Re: Televisions

#43 Post by Rwy in Sight » Sun Dec 08, 2019 6:13 am

TheGreenGoblin to be fair with the US and their NTSC system (nasty people used to say the initials stand for Never The Same Colo(u)r) was build to use the current technology available back then in the US - or so I was told by a person working on a TV factory.

There was a French system as well called SECAM obviously slightly different and it worked quite well although it was less used around the world.

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Re: Televisions

#44 Post by TheGreenGoblin » Sun Dec 08, 2019 6:29 am

Rwy in Sight wrote:
Sun Dec 08, 2019 6:13 am
TheGreenGoblin to be fair with the US and their NTSC system (nasty people used to say the initials stand for Never The Same Colo(u)r) was build to use the current technology available back then in the US - or so I was told by a person working on a TV factory.

There was a French system as well called SECAM obviously slightly different and it worked quite well although it was less used around the world.
As usual the French went their own way with SECAM and PAL SECAM is very good using FM sub-carriers to provide additional colour information. FM is not subject to as much signal distortion. The US and Japan (NSTSC) fell foul of being an early adopter of a colour standard that tried to be fully back compatible with the existing Black and White standard based upon the AC cycle rate of their mains electrical systems. The US would claim (correctly) that NSTSC has less flicker than PAL mind at 60 Hertz versus the lower 50 Herts rate associated with PAL.

In the end watching repeats of Columbo is pretty much the same whatever the system! =))
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Re: Televisions

#45 Post by ian16th » Sun Dec 08, 2019 8:30 am

In the early days of colour TV in the UK, the big challenge was watching and following Pot Black, on a b&w TV!

1 white ball and 7 shades of grey ~X(
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Re: Televisions

#46 Post by ian16th » Sun Dec 08, 2019 8:36 am

Brazilian TV was PAL and they have 60 c/s mains!
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Re: Televisions

#47 Post by Pontius Navigator » Sun Dec 08, 2019 8:59 am

Another thing I recall from our 9 inch B&W was the recommended viewing distance was about 8-9 feet. Probably so you couldn't count the lines.

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Re: Televisions

#48 Post by TheGreenGoblin » Sun Dec 08, 2019 10:10 am

ian16th wrote:
Sun Dec 08, 2019 8:36 am
Brazilian TV was PAL and they have 60 c/s mains!

They, probably,decided to go for the better standard and use a frequency converter in the TV circuits and/ or do something like this...


https://caninfotech.com/technology/how- ... al-region/

In fact...
In Brazil, PAL is used in conjunction with the 525 line, 59.94 field/s system M, using (very nearly) the NTSC colour subcarrier frequency. Exact colour subcarrier frequency of PAL-M is 3.575611 MHz. Almost all other countries using system M use NTSC.

The PAL colour system (either baseband or with any RF system, with the normal 4.43 MHz subcarrier unlike PAL-M) can also be applied to an NTSC-like 525-line (480i) picture to form what is often known as "PAL-60" (sometimes "PAL-60/525", "Quasi-PAL" or "Pseudo PAL"). PAL-M (a broadcast standard) however should not be confused with "PAL-60
https://en.m.wikipedia.org/wiki/PAL
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Re: Televisions

#49 Post by TheGreenGoblin » Sun Dec 08, 2019 11:24 am

Modern digital television and all our computer digital video media, standards, formats and compression algorithms probably have this Indian chap, Nasir Ahmed, to thank for inventing the Discrete Cosine Transform. I suppose we should also give a large hat tip to Frenchman Jean-Baptiste Joseph Fourier and folks like Leonhard Euler, Jean le Rond d'Alembert, and Daniel Bernoulli (the latter also being much beloved of pilots). I mean what did experts and theoretical mathematicians ever give us?

DSP (digital signal processing) is the rock upon which modern communications, radar, sonar, space communications etc. etc. is built and all thanks to the folks who gave us computers...

We do live in a marvelous world in many ways and yet what do some (like me) do with these inventions apart from posting images of boobs and the occasional aircraft image on fine internet sites like this one... ;)))
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Re: Televisions

#50 Post by Groundgripper » Sun Dec 08, 2019 11:37 am

Of course, another (often ignored) aspect to take into consideration is how good is your eysight? Without 20-20 vision, a multi-coloured blur at the other end of the room looks much the same in 4K, 8K or, for that matter 625 line non-HD.

GG

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Re: Televisions

#51 Post by Pontius Navigator » Sun Dec 08, 2019 11:50 am

GG,I already mentioned that.

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Re: Televisions

#52 Post by TheGreenGoblin » Sun Dec 08, 2019 12:13 pm

Pontius Navigator wrote:
Sun Dec 08, 2019 11:50 am
GG,I already mentioned that.
Maybe GG isn't wearing his glasses thereby proving both your points... ;)))
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Re: Televisions

#53 Post by Pontius Navigator » Sun Dec 08, 2019 1:15 pm

Remember the white spot? The picture would vanish and rumour had it that you could still see the picture as it vanished to infinity.

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Re: Televisions

#54 Post by Groundgripper » Sun Dec 08, 2019 1:25 pm

GG,I already mentioned that.
Sorry PN, I missed that, even with my glasses on. ^:)^ So much for speed-reading! #-o

GG

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Re: Televisions

#55 Post by TheGreenGoblin » Sun Dec 08, 2019 1:41 pm

We had a black and white set and I enjoyed seeing the Benham Disc produce a faint colour on it before we got a colour set...



I must be honest and say I couldn't see any colour in that experiment as shown in the video save for the faintest hue of blue in the manual spin at the end.

Better seen here..

https://michaelbach.de/ot/col-Benham/index.html
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Re: Televisions

#56 Post by Fox3WheresMyBanana » Sun Dec 08, 2019 1:45 pm

My mother's first job out of school was assembling television circuit boards. All hand-done in those days. There was an absolute priority on speedy accuracy, and a remarkably mature training scheme for the time. After a year, with bonuses, she was on higher wages than her dad.

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Re: Televisions

#57 Post by ian16th » Sun Dec 08, 2019 1:53 pm

Pontius Navigator wrote:
Sun Dec 08, 2019 1:15 pm
Remember the white spot? The picture would vanish and rumour had it that you could still see the picture as it vanished to infinity.
My parents had a B&W Ecko TV with a feature called 'Spot Wobble'.

This caused the line scan to oscillate and fill in the gaps between the 405 lines.

To my eyes, it put things out of focus, but my parents liked it.
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Re: Televisions

#58 Post by OFSO » Sun Dec 08, 2019 3:23 pm

it vanished to infinity

No it didn't. It went to the back of the CRT, we used to fish them out of the cabinet at the end of the week and put them in the garbage

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Re: Televisions

#59 Post by Pontius Navigator » Sun Dec 08, 2019 4:17 pm

ian16th wrote:
Sun Dec 08, 2019 1:53 pm
Pontius Navigator wrote:
Sun Dec 08, 2019 1:15 pm
Remember the white spot? The picture would vanish and rumour had it that you could still see the picture as it vanished to infinity.
My parents had a B&W Ecko TV with a feature called 'Spot Wobble'.

This caused the line scan to oscillate and fill in the gaps between the 405 lines.

To my eyes, it put things out of focus, but my parents liked it.
If course, having paid extra they had to like it. The luxury of putting it in its box in the garage didn't exist in those days.

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Re: Televisions

#60 Post by llondel » Sun Dec 08, 2019 7:52 pm

ian16th wrote:
Sun Dec 08, 2019 8:30 am
In the early days of colour TV in the UK, the big challenge was watching and following Pot Black, on a b&w TV!

1 white ball and 7 shades of grey ~X(
That was Ted Lowe's famous comment:
and for those of you who are watching in black and white, the pink is next to the green.

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