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Here we go.

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More stuff about the beginnings of color TV.

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We’re continuing from the last video so
click up above if you got here somehow without

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seeing those or find the link down in the
description.

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I’m back in a long sleeve shirt cause I’m
about to go to work, so let’s get cracking.

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NTSC often received the nickname “Never
The Same Color” or similar due to its reliance

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on the phase offset alone to determine hue.

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Unless the television set was dead on the
money with the way it handled the color burst,

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it would be very likely that it decoded the
chroma data slightly out of phase and the

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color would be messed up.

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The tint control on a television would allow
for manually shifting the reference point

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from the color burst to correct for errors,
with incorrect skin tone usually being how

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one identified a problem.

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After vacuum tube circuitry was replaced with
transistorized equivalents, most of these

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problems went away, and automatic tint control
eventually became standard on television sets.

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By the mid 1970’s, broadcast equipment had
progressed to the point that the color burst

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was always transmitted with the exactly correct
phase, pretty much removing the need for tint

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control altogether.

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PAL, the standard in most of Europe, reversed
the phase of the color encoding on each alternate

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scan line, hence its name Phase Alternating
Line.

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This made it such that a tint control was
not needed as the television would automatically

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find the correct phase offset through averaging
the alternate lines, and thus PAL was generally

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deemed superior.

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Europe received color television more than
a decade after the US, in part because of

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the more challenging geography of Europe.

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The NTSC system would drift color badly if
transmission conditions weren’t more or

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less ideal.

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So Europe waited patiently for a better system,
which PAL most certainly is.

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Telefunken in Germany patented PAL, the work
of Walter Bruch, in 1962.

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The first broadcasts of this new system occurred
in 1967 on BBC 2 in the UK.

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Apparently this was of the Wimbledon Championships
and let me just say that as an American, my

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reaction to learning this fact was “Of course
it was Wimbledon”.

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ON THAT NOTE, I was rather annoyed by this
sort of comment.

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And I’ll tell you why.

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Just pause for a minute as ask yourself, was
NTSC a choice?

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How could it have been a mistake?

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It was the first broadcast black-and-white
compatible color television transmission scheme

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on the planet.

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PAL is virtually identical to NTSC with the
exception of the alternating phase.

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Of course it would be better, it was developed
later, specifically to address NTSC’s weaknesses.

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We were stuck with it in the States because
it was already there, and we weren’t about

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to pull the plug on an existing standard.

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That’s the whole reason we spent so much
time making color TV compatible with black

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and white sets.

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I think many people appreciate PAL’s much
higher image resolution of 625 lines verses

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525 in the US, but that extra resolution came
at the expense of a reduced frame rate.

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And speaking of framerates,

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One commenter on the last video was singing
the praises of PAL because, with a framerate

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of 25 FPS, movies running at 24 frames per
second just need to be sped up by 4% to be

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converted to a PAL broadcast.

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I’m sorry, but I completely disagree with
that being “better”.

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I don’t want to just speed up the film!

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We used Three-Two pull down, which sort of
blended frames together by advancing the film

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frame between television fields.

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In effect some film frames were shown over
two fields, and some three.

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Most people, in fact I’d say virtually all
people, can’t see this, since the fields

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aren’t drawn together.

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And since it leaves the runtime and audio
as they should be within .1%, I’d much rather

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do that!

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And speaking of speaking of framerates, lets
discuss the 29.97 frames per second nonsense

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brought to you by NTSC.

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Matt Parker of Standup Maths made a video
about this very thing, which I shall link

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to now.

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Simply put, the carrier frequency of the audio
signal could interfere with the chrominance

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carrier and produce a visible dot pattern
on the screen.

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To keep this from happening, the audio carrier
frequency needed to be an integer multiple

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of the line rate.

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Which it wasn’t.

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So, something had to give.

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You couldn’t just change the audio carrier,
though, cause that would mess up existing

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TVs.

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But you could change the line rate, or frequency.

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By reducing the line frequency from 15,750
Hz to 15,734 Hz the audio carrier was now

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exactly 286 times the frequency of the line
rate, rather than some nasty number.

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This would minimize interference and prevent
the dot pattern from occurring, and existing

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television sets wouldn’t be bothered by
the change as their vertical hold circuitry

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was designed to compensate for slop in the
vertical retrace frequency.

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Of course, lowering the linerate lowered the
frame rate, as it’s still 525 lines per

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frame, so the frame rate was lowered to 29.97
frames per second entirely as a side-effect

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of compatible color.

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In PAL countries, this wasn’t ever an issue.

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It turns out backward compatibility wasn’t
ever on anyone’s mind in europe, or at least

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those disinterested in it won out.

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For example, in the UK, BBC2 started black
and white 625 line broadcasts in 1964, and

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owners of older 405 line televisions just
wouldn’t get to see it.

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This was about 10 years after NTSC had started
broadcasting.

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And PAL was based on the 625 line standard,
and likely due to the known framerate debacle,

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the audio carrier in this standard was specified
to be an integer multiple of the linerate,

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15,625 hertz.

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Thus the frame rate could stay an even 25
frames per second once color broadcasts began

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without the audio carrier affecting the image.

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In the previous video, I said that because
the chrominance carrier is suppressed during

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transmission, most of the interference between
chrominance and luminance is eliminated.

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But not all of it is.

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Black and white televisions made after the
changeover to color were designed to filter

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out this interference, but earlier televisions
or cheaper ones without the filter circuit

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would display a pattern of dots in highly
colored areas of the screen.

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The dots were a visible manifestation of the
chrominance carrier’s interference.

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Now, I’m going to make a speculative statement
because I couldn’t find anything to confirm

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or deny this after hours of poking about online,
so here goes.

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Because the luminance signal is used in calculating
I and Q, it seems to me that the luminance

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signal itself must be manipulated at precise
times to actually create changes in the calculated

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I and Q values, otherwise it would seem their
calculated output would always be the same

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for a given brightness.

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I believe that the chroma dots are the visual
manifestations of this happening.

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I have read that the dots are most visible
in highly colored areas, which makes sense

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as the amplitude of the chroma carrier dictates
the saturation of a color, and the phase difference

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the hue.

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It therefore sounds to me like the Y carrier
is constantly being altered along with color

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information, and that alteration appears as
dots.

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If that’s not at all why the dots appear
please comment below.

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ANYWAY, the dots would turn out to be useful
in the 21st century.

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Many older television programs were recorded
onto videotape masters that were re-used to

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lower production costs.

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With these master tapes lost, the only copy
of the TV shows that remained were on film,

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transferred via telecine.

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In many if not most cases, this film was black
and white.

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This had led to many of these early color
television shows only being preserved in black

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and white.

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But some TV studios used a telecine to capture
the output from a black and white monitor

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that didn’t filter out the chroma dots.

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Using modern software, these dots have been
used to reconstruct the color.

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By carefully examining the magnitude and position
of these dots, the color information can be

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extracted.

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This wasn’t an easy task, mind you, particularly
with the extra geometry component added by

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the curved glass screens of the monitors,
but it’s still an amazing thing.

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I’ll link to some more info down below if
you’d like to learn more.

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Now let’s talk a bit more about Guillermo
Gonzalez Camarena.

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Two videos ago I briefly talked about him
and his clever but ultimately inadequate color

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wheel adapter for black and white televisions.

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He’s also known for inventing a CRT with
two electron guns rather than three.

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This would supposedly make color televisions
cheaper to produce.

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However, there are two glaring problems with
attributing him to “inventing” that.

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First, if there were an individual who were
to have experimented in two color TV long

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before Gonzalez Camarena, who would you guess
that to be?

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Anyone?

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Anyone?

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I’ll give you a hint, he’s Scottish!

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That’s right, it’s JOHN LOGIE BAIRD.

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He’s a persistent little bugger, isn’t
he?

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Now I’m starting to see why people feel
so strongly about his contributions to television.

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So first, two-color “color” can be achieved
using complementary colors.

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In fact, the first Technicolor films were
done with a red and green film strip all the

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way back in 1916.

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Baird used a really wonky looking picture
tube called a Telechrome which instead used

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cyan and red-orange phosphors.

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These two colors can produce a realistic skin
tone and a limited range of other colors.

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He came upon the concept for the telechrome
in 1942 and demonstrated it in 1944.

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Gonzalez Camarena’s idea is dated to 1963,
with one source saying 1962.

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Links are below.

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But a far more damning issue against Gonzales
Camarena is the fact the the 1953 NTSC standard

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includes support for two color receivers!

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That’s right, that whole I and Q business?

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It turns out, I on its own is a two color
gamut.

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A television could be built with cyan and
red-orange phosphors and demodulate only the

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I signal, and you would get a functional two
color TV.

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This may also help to explain why I is given
three times the bandwidth of Q.

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If it were meant to be able to produce a reasonable
color image on its own, it would make sense

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to prioritize bandwidth to I over Q.

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But the fact of the matter is, two color “color”
is never as good as three color.

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Skin tone might look right, but not much else
will.

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Thus, since you’d need almost the same amount
of manufacturing complexity to produce a two

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color CRT as a three color--still need a shadow
mask and phosphor grid, you’re really just

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losing one electron gun--it was never deemed
to be worth the significantly worse color

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fidelity in exchange for a few pennies saved.

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Many people correctly commented in previous
videos that the color wheel from the CBS system

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survived in single chip DLP projectors and
televisions.

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But you might not have known that for a brief
time in the 1950s, you could purchase a kit,

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called the Col-R-Tel, to convert your existing
black and white TV into color.

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By performing a few wiring modifications,
you could add a device which would extract

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the color data from an NTSC broadcast, alter
the CRT’s output to a sequential field system,

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and use a color wheel to reproduce the color
sequentially.

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Gonzalez Camerena’s work would actually
be a thing after all.

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There’s a great link down below, along with
many many others, if you’d like to learn

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more.

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And for my last tid-bit, a brief word on shadow
masks, aperture grilles, and Trinitron.

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I’m still planning on making a separate
video showcasing Trinitron, but some people

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have correctly pointed out that the CRT set
I’ve been using for demonstrations doesn’t

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have the same type of shadow mask that CRTs
of the time did.

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I do have a device which has the original
type CRT, but it doesn’t really fit well

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into this discussion.

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Well, here, I’ll show you.

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♫ Macintosh Startup Chime ♫

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Yep.  That’s it.

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Doesn’t really fit into the video, now does
it?

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Most CRT computer monitors--if not all that
aren’t Trinitron--use a design similar to

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what you’d find on the earlier color sets.

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These CRTs don’t have the individual triads
like you see here, instead it’s just a repeating

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pattern of red, green, and blue circles.

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Because of the high image resolution needed
in a computer monitor, a very fine dot pitch,

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the term used to describe how many dots appear
over a given length, was required.

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The CRT from the GE set uses a more modern
phosphor and shadow mask design which increases

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the phosphor-to-mask ratio, but at the expense
of a coarser dot pitch.

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This design was used in televisions to better
compete with Trinitron displays.

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But again, we’ll talk more about that later.

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As always, thank you so much for watching!

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I hope you enjoyed the video.

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If you’re new to this channel and liked
what you saw, please subscribe so you won’t

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miss the next ones.

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supporters on Patreon, especially these patrons

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who get their names in lights.

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Patreon supporters have allowed me to spend
much more time focusing on this channel, which

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is bringing videos to you more frequently.

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If you’re interested in helping out, please
check out my Patreon page through the link

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on your screen, or down below in the description.

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Thank you for your consideration.

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And, I’ll see you next time.

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(Exasperated) Wooh!

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Hoh, OK