Comments on: Color Television Comes True (Feb, 1947) http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/ Yesterday's tomorrow, today. Fri, 10 Feb 2012 18:19:00 +0000 hourly 1 http://wordpress.org/?v=3.1.4 By: James T. Hawes http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/comment-page-1/#comment-1063756 James T. Hawes Fri, 19 Dec 2008 23:38:39 +0000 http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/#comment-1063756 The article describes an early RCA color system, and not the NTSC system that the US finally settled on. NTSC combines two color signals onto one subcarrier. (The official name for the transmission mode is QAM.) At the transmitter, NTSC discards the subcarrier, except for bursts that occur between color lines. Sending three color signals is unnecessary, because the TV receiver reconstructs the missing third signal. The article mentions that monochrome sets could receive color pictures, but would require "frequency converters." As you know, NTSC color is viewable on monochrome receivers without such frequency converters. The necessity of a converter means that the TV system in the article isn't really compatible! Today's incompatible digital TV has the same problem. Most people, if they'd had a choice, would have held out for a compatible digital system. Instead, the government isn't allowing us that choice. See my page on the DTV boondoggle at... http://www.hawestv.com/mtv_FAQ/FAQ_dtv_chg1.htm In your article, notice the reference to projecting three color images and combining them. This reference proves that the three-gun, color picture tube wasn't public yet. Today, we still use descendants of the original, three-gun CRT. Of course, other technologies such as DMM, plasma, liquid crystals and OLEDs are rapidly obsoleting the poor CRT. The UK and European PAL and SECAM systems aren't really "better color." These systems have more lines of picture definition than our NTSC does. Yet these systems also transmit at fewer frames per second than NTSC does. The lower frame rate necessitates higher flicker. Brighter pictures accentuate this flicker. Also, the Europeans halve the vertical color resolution. PAL and SECAM take up more spectrum space than NTSC channels do. The more spectrum-thrifty NTSC is also less noisy. In the days when color sets were very expensive, Col-R-Tel cheaply adapted monochrome sets to color. To produce color on a monochrome set, Col-R-Tel electronics translated the picture into field-sequential color. That is, one color at a time. Viewing the picture through a synchronized color wheel, the viewer saw full-color pictures. Col-R-Tel proves that color wheel sets can work just fine, as long as they're compatible. Of course, unlike the ill-fated CBS system, Col-R-Tel was compatible with NTSC. So you see, the spinning wheel system, while crude by today's standards, is delightful and not "awful." A final note: Many NASA spacecraft have used color wheel TV cameras. Among these spacecraft were several Apollo missions and the Space Shuttle. For more detail, see my page on Col-R-Tel and the NTSC system at... http://www.hawestv.com/mtv_color/colrtel_101.htm. I also host a page on the Apollo moon landing color system. This system had many similarites with Col-R-Tel. See... http://www.hawestv.com/moon_cam/moonctel.htm # The article describes an early RCA color system, and not the NTSC system that the US finally settled on. NTSC combines two color signals onto one subcarrier. (The official name for the transmission mode is QAM.) At the transmitter, NTSC discards the subcarrier, except for bursts that occur between color lines. Sending three color signals is unnecessary, because the TV receiver reconstructs the missing third signal.

The article mentions that monochrome sets could receive color pictures, but would require “frequency converters.” As you know, NTSC color is viewable on monochrome receivers without such frequency converters. The necessity of a converter means that the TV system in the article isn’t really compatible! Today’s incompatible digital TV has the same problem. Most people, if they’d had a choice, would have held out for a compatible digital system. Instead, the government isn’t allowing us that choice. See my page on the DTV boondoggle at…
http://www.hawestv.com/mtv_FAQ/FAQ_dtv_chg1.htm

In your article, notice the reference to projecting three color images and combining them. This reference proves that the three-gun, color picture tube wasn’t public yet. Today, we still use descendants of the original, three-gun CRT. Of course, other technologies such as DMM, plasma, liquid crystals and OLEDs are rapidly obsoleting the poor CRT.

The UK and European PAL and SECAM systems aren’t really “better color.” These systems have more lines of picture definition than our NTSC does. Yet these systems also transmit at fewer frames per second than NTSC does. The lower frame rate necessitates higher flicker. Brighter pictures accentuate this flicker. Also, the Europeans halve the vertical color resolution. PAL and SECAM take up more spectrum space than NTSC channels do. The more spectrum-thrifty NTSC is also less noisy.

In the days when color sets were very expensive, Col-R-Tel cheaply adapted monochrome sets to color. To produce color on a monochrome set, Col-R-Tel electronics translated the picture into field-sequential color. That is, one color at a time. Viewing the picture through a synchronized color wheel, the viewer saw full-color pictures. Col-R-Tel proves that color wheel sets can work just fine, as long as they’re compatible. Of course, unlike the ill-fated CBS system, Col-R-Tel was compatible with NTSC.

So you see, the spinning wheel system, while crude by today’s standards, is delightful and not “awful.” A final note: Many NASA spacecraft have used color wheel TV cameras. Among these spacecraft were several Apollo missions and the Space Shuttle.

For more detail, see my page on Col-R-Tel and the NTSC system at… http://www.hawestv.com/mtv_color/colrtel_101.htm.

I also host a page on the Apollo moon landing color system. This system had many similarites with Col-R-Tel. See…
http://www.hawestv.com/moon_cam/moonctel.htm
#

]]> By: Gutie http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/comment-page-1/#comment-927228 Gutie Tue, 18 Dec 2007 20:17:52 +0000 http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/#comment-927228 As I recall the spec did change for the exact reason that they wanted a compatible color system. Amazingly enough the CBS spinning wheel has actually been approved and it was not compatible and had less resolution than the current 525 line B&W. The UK and Europe eventually better color becausee they did not require compatability. RCA in about 1960 or so b'cast a color show that only a few saw in color, but millions saw in B&W. The spinning wheel system would have been awful! As I recall the spec did change for the exact reason that they wanted a compatible color system. Amazingly enough the CBS spinning wheel has actually been approved and it was not compatible and had less resolution than the current 525 line B&W. The UK and Europe eventually better color becausee they did not require compatability. RCA in about 1960 or so b’cast a color show that only a few saw in color, but millions saw in B&W. The spinning wheel system would have been awful!

]]> By: glindsey http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/comment-page-1/#comment-926502 glindsey Tue, 18 Dec 2007 16:28:46 +0000 http://blog.modernmechanix.com/2007/12/18/color-television-comes-true/#comment-926502 I wonder if they were just simplifying the concept for the layman, or if there were changes to the spec before it was finally implemented, but their explanation of the color transmission -- using three frequencies, one for each color -- isn't really true. NTSC color data is carried on a frequency subchannel, but it isn't split into separate red, green, and blue channels -- instead the amplitude and phase indicates the overall hue. This allowed black and white sets to remain compatible with color transmissions, as they just ignored the new color subchannel, but still displayed the existing luminance information. I wonder if they were just simplifying the concept for the layman, or if there were changes to the spec before it was finally implemented, but their explanation of the color transmission — using three frequencies, one for each color — isn’t really true. NTSC color data is carried on a frequency subchannel, but it isn’t split into separate red, green, and blue channels — instead the amplitude and phase indicates the overall hue. This allowed black and white sets to remain compatible with color transmissions, as they just ignored the new color subchannel, but still displayed the existing luminance information.

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