Rca left everyone else at the alter

[Steve McVoy]

Though I have been assured that flicker was a real problem in 1950 when CBS demonstrated their system, I have yet to see it on the 10 inch Gray Research monitor in the musuem. Could the problem have been in the camera back then, and solved now by the use of Darryl Hock's standards converter?

http://www.earlytelevision.org/gray_monitor.html

Another serious problem with the CBS system is resolution. The picture is only 405 lines, compared to 525, but more importantly, with 4 mHz of video bandwidth it is only possible to get about 250 lines of horizontal resolution. On a 21 inch screen that would look pretty bad.

[andy]

---

[Sandy G]

Another thing were the giant egos involved. Sarnoff apparently was a world-class horse's arse-one of his quotes was-"I don't get ulcers, I GIVE them." Paley at CBS had a pretty high opinion of himself, too & Major Armstrong apparently was unable to "let it go", & that ultimately destroyed his life. Helluva shame-The Major & Sarnoff initially had been friends-one wonders what could have been accomplished if they'd been able to put aside their differences & worked together.-Sandy G.

[NowhereMan 1966]

Originally Posted by andy

I think either system could have worked very well. An all electronic solution to displaying CBS color would have been implemented early on. Mechanical color sets would be as rare as 15GP22 based sets are (except for projection sets where a small color wheel in front of the lens would work fine).

I think I remember reading a story somewhere on the web where in 1951, one guy when he was a kid used to tweak the oscillators the family TV set to receive the CBS 405 line color system tests in New York every night, in black and white of course. It was kind of interesting. I guess if the FCC took the CBS color system instead, they could always tweak the B&W sets out there to receive it.

I think I've read somewhere that Philo T. Farnsworth suggested the use of a 625 line picture standard in 1941 when the FCC was settling on the TV standard we use today.

[NowhereMan 1966]

Originally Posted by Sandy G

Another thing were the giant egos involved. Sarnoff apparently was a world-class horse's arse-one of his quotes was-"I don't get ulcers, I GIVE them." Paley at CBS had a pretty high opinion of himself, too & Major Armstrong apparently was unable to "let it go", & that ultimately destroyed his life. Helluva shame-The Major & Sarnoff initially had been friends-one wonders what could have been accomplished if they'd been able to put aside their differences & worked together.-Sandy G.

A side note, IIRC, when the World Trade Center was hit on 9-11, WNBC-TV lost their antenna and theyh ad to erect a quick backup antenna on, you guessed it, on Edwin Howard Armstrongs old FM tower at Alpine, New Jersey. Bet Sarnoff was spinning in his grave on that one.

[wa2ise]

Originally Posted by Sandy G

Major Armstrong apparently was unable to "let it go", & that ultimately destroyed his life. Helluva shame-The Major & Sarnoff initially had been friends-one wonders what could have been accomplished if they'd been able to put aside their differences & worked together.-Sandy G.

This is only my conjecture and impossible to prove, but I suspect that Sarnof, when he asked Armstrong to develop noise free radio reception, wanted noise free *AM* radios that could receive existing RCA NBC owned AM stations. Armstrong delivered FM, which was low noise but (and this was likely a BIG BUT) required new broadcast stations and transmitters and a new band. Which would take time and be expensive. Would also require trying to sell FM radios in markets with only a few stations. Also (and this is probably the really big issue) FM would distract and suck off consumers away from Sarnoff's next big thing: Television. Maybe if Armstrong had suggested using FM sound for the soundtrack for television images to Sarnoff, Sarnoff might have seen this combo as a "killer application" product. A one-two punch. "Great sound and you also get to watch the action too".... Then the Armstrong Sarnoff pjssing contest might not have happened....

As for the shadowmask color CRT, Heard that Philco was trying to develop a color CRT based on other methods. "Apple" code name, saw it somewheres on the web. There's the stripes of colored phosper on the screen and a single electron beam idea, the beam switched RGBRGB in time step as it sweeps
across the phosper stripes. Issues on keeping track of which colored stripe the beam is now hitting area major problem for this scheme. Especially when the image has large black areas, you lose track. Would have gotten rid of convergence problems though. But so did the color wheel, but that had motion artifacts and wasn't compatable with B&W NTSC.

[frenchy]

[QUOTE=Pete Deksnis]Perhaps the thrill of finally seeing CBS sequential color live clouded my objectivity. But I do not recall observing color fringing on the small-screen, operational 1951 CBS-color equipment at the 2004 ETF convention. Small screen is probably the operational word; field sequential color on today’s hi-acreage bottles would change the picture. >>

Yeah those Wisard of Oz screen photos are spooky looking, because it's the same 'pure' scanning line of a black and white screen, except with color...no dots, no misconvergence whatsoever.

Frenchy

[old_tv_nut]

My impressions of the field-sequential demo at ETF:

Viewing close-up on fast motion I could see some color fringing - but as expected, the fringing was mainly on the part of the image you are not fixed on. If you are tracking a moving object, it is fringe-free, but the background has fringes; if your eyes are stationary, the moving object has fringes.

Viewing from the back of the room (pretty useless for the small screen), you could see color "flashing" as your eyes moved (really, gross fringing of the whole image).

One thing I noticed is that at the brightness levels used, the flicker was not really bad. I always wondered what that would look like. I could see some. Flicker is a very strong function of brightness and scan rate, and a fucntion of individual threshold to a lesser extent. I think personal differences would easily account for Steve not seeing it.

Flicker was much worse on the Colortel converter which was using a color wheel on NTSC scan rates, and I would be surprised if anyone could not see it.

My former boss at Zenith saw the original CBS demos, and always said that the CBS system color reproduction was the best of the systems at that time. But of course, the recent demos all start with an NTSC source, so the original results cannot be judged until we have a color wheel camera operating.

If the demos last year were converted from NTSC composite they would have the reduced color bandwidth, but that may not have been noticeable on the small screen either. I am wondering now if the converter took in NTSC composite, or YPbPr for better color bandwidth.

[oldtvman]

back then they didnt have servo drive circuits with micro's controling syncronous motors, my guess is that from time to time the scan rate would have a timing error between the camera and the color receiver. i worked on many of the newer pll motor drive circuits, and i find it amazing that they got as good a picture as they did back then

[Pete Deksnis]

"If the demos last year were converted from NTSC composite they would have the reduced color bandwidth, but that may not have been noticeable on the small screen either. I am wondering now if the converter took in NTSC composite, or YPbPr for better color bandwidth."

The converter had inputs for NTSC composite and S-video. All the demos in 2004 were with a composite input; an S-video cable was not available.

As I recall, Darrell said there were too many issues involved for component video.

[Steve D.]

I also witnessed the demo. at ETF last year. It was spectacular and the highlight of the convention. No matter the video source it was a treat to view, for the first time in over 50 years, the field sequential system in action. The anticipation was palpable. You could hear a pin drop as the color wheels were powered up to speed and finally produced their full color pictures. The applause broke the silence. I had a sense of what the CBS engineers felt during their trials.


-Steve D.

[tubesrule]

Hello everyone. I guess I need to check this board more often

Quite a few questions have been raised about the CBS format and my converter. First the question of color fringing:

Color fringing is visible on the operating CBS sets using the converter, just to a lesser extent than would have been apparent originally. In the CBS system, a complete color image is made up of 6 fields repeated as RBGRBG. (Since it still used interlaced scanning, it required two sets of RBG sequences to make up the entire color frame since each color had to appear in both fields.) In the original system, if an object moved in any direction horizontally or vertically, it's component colors would separate. The amount of separation is proportional to the speed the object moves relative to the scanning speed in that direction across the 6 fields. In this system, each of the 6 fields could be temporally different from the previous one, and since each field represented a different color, color fringing would occur.

Since we are converting from NTSC which contains 2 fields for each color frame, only 2 groups of 3 fields in the converter output can be temporally different per frame. While this tends to decrease the number of fields that appear different, the time difference between the 2 fields in the NTSC input is greater than the difference between two fields in the CBS system making this worse.

To sum it up, because of the nature of the NTSC input, and the frame rate conversion, there is less color fringing in the output of the converter than what would have been observed originally, the field sequential source being the main difference.
As a side note, the converter performs a trick that senses if the original NTSC video came from a progressive source like a telecined movie, in which case it reconstructs the original 24fps progressive movie, which exactly matches the CBS frame rate, so no color fringing appears at all.


Of course none of this addresses the issue of darting your eyes around or moving an object quickly across the screen and seeing the color image break apart. This is inherent in any field sequential system, and is the same today using the converter as it would have been originally. I think this is the effect that most folks noticed when viewing these sets last year.


As for this being a viable option for color, keep in mind that while the frame rate was low on the CBS system to keep the bandwidth down, the field rate was at 144Hz. Compare this to most state-of-the-art single chip DLP projectors that use 4X (120Hz) or some that use 5X (150Hz) field rates. While the DLP projectors have the advantage of coming from non-field sequential sources, they will appear similar to what the CBS system would have looked like.


Someone mentioned the flicker difference between the CBS and ColorTel demonstrations last year. Remember that the CBS system while using a low 24Hz frame rate gave a complete color image at this rate. (actually your eye perceives a complete color image at 48Hz with the CBS system) while the ColorTel converter uses 6 NTSC fields to make a color frame at a 5 Hz rate. (similarly your eye will perceive a 10Hz rate with the ColorTel) This is why the CBS is basically flicker free while the ColorTel has objectionable flicker.


On the converter it self, only a composite and S-Video input were provided. As Steve McVoy mentioned, one of the downsides to the CBS system was it's relatively low bandwidth. The composite input is nice as it connects to just about anything, and the S-Video input is a component format, with the same Y bandwidth as a full YUV input, but with just somewhat less color bandwidth. Because the cost and size of the unit would have gone up with the addition of a YUV input, and the additional color bandwidth would not have been realized, it was decided to leave this off.

Hope this wasn't too long and boring of a post

Darryl

[tubesrule]

One thing I forgot to mention, in the section about how the converter handles telecined material, this would have been true back in 1950 as well. A film telecine chain would have been able to provide a pull down sequence in the CBS format that caused no color fringing. Color fringing would have only occured on material sourced from a camera.

Darryl

Most of that was over my head (just like those flying cows) but I found it most interesting and appreciate your having taken the time to write it!

[old_tv_nut]

"As a side note, the converter performs a trick that senses if the original NTSC video came from a progressive source like a telecined movie, in which case it reconstructs the original 24fps progressive movie, which exactly matches the CBS frame rate, so no color fringing appears at all."

Not quite right - The fringing disappearas with a live 144 field camera. There is still color fringing if the object motion (or stillness) and your eye motion (or stillness) don't match. So, even in the 24 frame film case, you see fringing.

What happens on a moving object with 24 frame source: Your eye tracks the average motion, so on the R.B,G,R,B,G...etc fields, your eye is at equally spaced positions 1,2,3,4,5,6, for a first film frame and 7,8,9,10,11,12 for the following film frame. but the object is reproduced 6 times at position #1 for the first film frame, and then 6 times at position #7 for the following film frame, and so on - never at the other positions where your eye is centered at those times. Since the images are stationary for 6 fields while your eye is moving, the R,G,B fields fall on different locations of the retina, and voila! you have fringing. The high field rate helps reduce it, but cannot eliminate it.

Now, if you have a live camera, the object will be reproduced at all those positions at the right times, so if your eye is tracking the average speed, you see no fringing on the moving object. (However, the stationary background objects will show fringing -- oh well.)

The conversion from a different frame/field rate can create different (and maybe worse) fringing since the source images show the object in different positions compared to the 144 field or 24 frame cases.

Micromirror TVs break up the pulse of light for each frame into subframes in order to make a gray scale from a basically on/off procedure. Current sets with color wheels use carefully crafted algorithms so that the color fringing is reduced by the particular sequence of light pulses giving the gray scale, as well as by the high frame rate. Color fringing, which could be quite visible on early units, is mostly invisible these days, although you can still see some color breakup if you stand far away and move your eyes rapidly.