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Fifty Years of Color Television
peter303 writes "The Houston Chronicle notes that color TVs were first manufactured on March 25, 1954 at a price of $1000 (about $4000 in today's dollars). Some of the older folk here remember the excitement of your first neighbors acquiring one of these in the 1960s and as the TV series one-by-one switched to color. Ironically, for such a high tech nation, there hasn't been a major quality improvement in TV broadcast images for a half-century until the 2006 changeover to HDTV."
According the US Labor Dept Inflation Calculator, a $1000 TV in 1954 would cost about $6900 in 2004 dollars - about the price of a nice High-Def Plasma...interesting.
what about the quality in video cameras
Yes, the advent of CCD cameras has eliminated the hassles of registration that were such a headache in tubed cameras, and the availability of digital filtering has also helped to reduce artifacts in the encoded NTSC.
--- Bill
What is a non-integer frame rate?
The frame rate in monochrome television was 30fps. In NTSC, it is 29.97fps. This leads to the need for "drop-frame" timecode, and other delights.
Drop-frame attempts to correct for the time errors by dropping two frame addresses periodically. The algorithm is that the first frame of the first second of each minute not evenly divisible by ten is identified as frame 2, not frame 0. The 18 frames per 10 minutes thus dropped reduces the cumulative error to a little more than 2 frames per 24 hours.
There are other techniques recommended for reducing the residual further.
--- Bill
Can you provide a link to this "non-integer frame rate" please?
e ld_NTSC _sequence/index.html
Look here:
http://www.poynton.com/notes/video/Four-fi
--- Bill
In theory, the quality should have been OK, and perhaps it was in a studio, on a high-quality monitor, via closed circuit.
In practice, the home receivers of the late 1950s and 1960s were lousy. They were very temperamental beasts. They had no built-in degaussers and if you moved them or turned them you'd get color changes due to the earth's magnetic field.
The tube circuits were unstable and drifted. They had no ability to compensate for any signal variation, so colors shifted from program to commercial, from program to station break, from program to program, and sometimes from camera to camera within a program. You were constantly leaping up to fiddle with the contrast, brightness, saturation, and hue adjustments.
The tubes were never properly converged (and had about seventeen tweaks needed to converge them).
The picture tubes were circular rather than rectangular and cut off significant parts of the picture. The phosphors couldn't deliver much brightness, so they couldn't put the usual neutral tint in the CRT face; a set when turned off looked pale grey rather than dark. When turned on, room light washed out the colors (and if you turned the brightness up the picture looked even worse).
They were trophies and icons of conspicuous consumption, but it wasn't much fun watching them. I've often suspect that at least part of the reason for the popularity of the Disney show is that animated cartoons were relatively unharmed by slight color distortions.
In the 1970s, solid-state circuits and the introduction of various AGC and other automatic-adjustment features finally brought home receivers to the point where they were worth watching.
"How to Do Nothing," kids activities, back in print!
Check out this link to read more on it. Also this link has some interesting info.
That definition was declared by the Brits, and SECAM was also defined as Something Essentially Contrary to the American Method.
I've worked in television for over 30 years, and although there are certainly shortcomings in the NTSC standard, they are dwarfed by the failings in the delivery systems (transmitters and cable systems), so that the resolution visible in the living room has typically been about 50% of that seen in production rooms.
--- Bill
No improvements??!! Don't you remember "vert. hold" and having to adjust that up until sometime in the 80's. IC-based PLL circuitry has really improved TV since the transistor and tube days.
Actually, the problem is that the frame rate is not an exact integer multiple of the 60Hz AC power frequency, which is usually the largest source of electrical noise. It's off by a fraction of a percent; that's why you often see a distortion slowly creeping up the screen about once per minute as the frame rate beats against the power line sine wave. If the frame rate were exactly locked to the power line frequency, the distortion wouldn't move, so you wouldn't notice it.
Uhhh... Okay. Credentials: Former professional video technician (at the SkyDome in Toronto) before being hired to design radar video systems for Litton. Also an avid collector and restorer of early television sets.
In the 1950s, AC power was not universal, especially in rural areas (note the sustained popularity of the "All American Five" AC/DC table radio at that time). Lots of places had DC, and lots of cities had 25Hz power well into the late 1950s. Nor was it necessarily going to be in sync from one town to the next, so you couldn't guarantee that the 60Hz powerline hum could be synchronized with the TV station's 60Hz vertical signal. In other words, you couldn't be guaranteed that the hum was going to happen in the vertical blanking interval (that black bar you see rolling when the vertical hold control is set wrong).
I suspect that the vertical was chosen to be at 60Hz more because the large current draw of the vertical output tube driving the deflection yoke would then be more likely to occur during the charge cycle of the set's filter capacitors, allowing smaller capacitors to be used (cheaper). This of course being a time when electrolytic filter capacitors (in fact, all small parts) were still hand made.
Even more importantly, you should remember that most early TV sets (until the advent of selenium rectifiers in about 1955) had full-wave rectifiers, generally using a 5U4 or similar tube. A full-wave rectifier folds the negative half of the sinewave up to the positive side, which effectively doubles the frequency to 120Hz.
Either way, if the set is operating correctly, regardless of color standard, you will not see any powerline artifacts or ripple. It's when the horizontal system starts to come out of resonance that the biggest current draw happens in the set. Your horizontal output tube (transistor) consumes the most power of any part of the set; if a typical 1950s DuMont or Admiral has a cathode current of 120mA (at ~300V) and you misadjust the horizontal hold, that current will spike to over double that. That will load down the set's power supply, discharge the filter capacitors more, and you might start to hear 120Hz (full wave rectifier at 60Hz) hum in the set's speaker.
IIRC, the original B&W broadcast was at 60 frames/second, but there was some technical reason they had to slightly shift it in order to add the color subcarrier.
Yup. The original NTSC standard was 30FPS; when the 3.58MHz sinewave which carries color was added, the bandwidth of the signal had to be increased. (The original was 3.5MHz bandwidth for the image; reducing the frame rate slightly was sufficient to keep the bandwidth inside the original spectrum and didn't screw up many of the existing TV sets.)
Old B&W TVs were the worst with this noise distortion because they weren't designed to try to prevent it.
Note that the NTSC color TV standard was adopted in 1953, though not implemented until 50 years ago today. Every TV set built since then has known about the new frame rate the sets would have to handle. I actively collect and restore early TV sets, and I only have a few which predate this - they're rate.
Again, you don't get powerline beat in the picture unless something is wrong with the set's filter capacitors.
If you're getting a beat in the picture which, on a blank raster, moves in time with the vertical hold control, then you've got a problem where the vertical is either consuming too much current, or a
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