CBS Chromacoder

[John Hafer]

Hello All:

I am an early color TV buff and am trying to find out more information about the early CBS Chromacoder system.

It is my understanding that when the FCC finally approved the NTSC color system in 1953, CBS came up with a system that could convert the output from their original color wheel color cameras and convert them to an NTSC signal.

I would think that this would have been a very cost effective system since these cameras were B&W single tube cameras with a mechanical color wheel mounted in front of the pickup tube, i.e., like the flying spot scanner systems, versus the more complex 3-tube (RCA-TK-40/41) cameras of their time.

It apparently did not work well since CBS ended up purchasing some RCA cameras back then.

See the link:
http://www.earlytelevision.org/chromacoder.html

Anyone know of this system or have any more information on it?

Thanks.

[Steve D.]

John,

Check out this site's CBS color camera page for photos of the CBS Chromacoder camera. This was an RCA TK-30 B&W camera modified for color pickup.

Eyes of a Generation - A Web site dedicated to the collection, restoration, and preservation of classic broadcast television equipment.
Address:http://www.eyesofageneration.com/CBS_Color.php

-Steve D.

[cbenham]

[QUOTE=John Hafer;2827488]Hello All:

I am an early color TV buff and am trying to find out more information about the early CBS Chromacoder system.

I have some good technical information about the Chromacoder System but its a 6 MB .pdf. Can someone host it?
Cliff

[old_tv_nut]

[QUOTE=cbenham;2837661]

Originally Posted by John Hafer

Hello All:

I am an early color TV buff and am trying to find out more information about the early CBS Chromacoder system.

I have some good technical information about the Chromacoder System but its a 6 MB .pdf. Can someone host it?
Cliff

I could put it on bretl.com

[cbenham]

That would be great. I'll forward the file to you.

[old_tv_nut]

I just realized I can't post this. I checked and IEEE still holds the copyright. They refer purchases of older articles like this to infotrieve, which charges memebers $12 for the service and non members an additional $17.50 copyright fee. I know this is a PITA, but IEEE is struggling with their financial model and hasn't figured otu a way to support free distribution.

I would get in trouble if I posted it without obtaining the rights. I will continue to look into that possibility

For now, I will have to default to posting the information on how to purchase it.

Sorry, wish I could put it up right away.


The infrotrieve link is:
http://www4.infotrieve.com/customize.../ieeelogon.asp

The requested article is:
Chromacoder Colorcasting

Lloyd, C. G.
Manager, Broadcast Equipment Engineering, General Electric Company, Syracuse, New York
This paper appears in: Broadcast Transmission Systems, IRE Transactions on
Publication Date: March 1955
Volume: PGBTS-1 , Issue: 1
On page(s): 49 - 54
ISSN: 0099-6866
Digital Object Identifier: 10.1109/TPGBTS.1955.4505126
Current Version Published: 2008-05-07

[old_tv_nut]

A search of the IEEE rights indicates that they will license for print media or CD/DVD (cost for these options unknown), but not for on-line posting.

[old_tv_nut]

One thing:
John Hafer said "a system that could convert the output from their original color wheel color cameras." The Chromacoder cameras operated at three times NTSC rates instead of CBS color rates, and the scan was rotated ninety degrees so the scan lines would not cause moire' patterns with the NTSC scan lines.

[old_tv_nut]

If i understand the 90-degre scanning properly, each NTSC fileld coming from the Chromacoder would be made of portions of 3 old and 3 new sequential fields, like this:

[ceebee23]

I assume CBS dumped the Chromacoder and the field sequential cameras because the RCA color cameras were better???

I assume that flicker and breakup issues would have also been an issue?

But wasn't the camera used for the Apollo space flights essentially a field sequential camera with some sort of NTSC encoding in much the same way?

I imagine the CBS cameras would have been much lighter and easier to move and maintain than the early tri-tube NTSC cameras.

[Steve McVoy]

I just posted a new article about the Chromacoder:

http://www.earlytelevision.org/chromacoder.html#r-e

[BrianSummers]

Hi
you might be interested to know that EMI in the UK had a go at a field sequential colour (UK spelling!) camera. see http://www.tvcameramuseum.org/emi/ex...2/seqcolp1.htm
This was an experimental colour wheel camera using a similar arrangement of 3 CRTs and 3 cameras looking at them, as sort of standards converter. I have a write up on it somewhere but it was much the same as the CBS one.

There were many defects and a lot of electronics to go with it all, but at that time there were not many choices for colour cameras the only good (ish) was the BIG 3 IO option.

Regards Brian S

[whsh93a]

I still remember tuning into a CBS program in the late 50's (I think it was a movie) and discovering color on my family's B/W Motorola set. It was there, but pretty dim. As a kid, I always wondered if I was seeing things until I read one day years later that they had conducted experiments to fool the brain into seeing colors on standard B/W sets. It only worked for a percentage of people. I guess I was one of them??

Maybe I'm not remembering correctly (old memories can change and fool the rememberer). Anyone know anything about this?
DH

[JBL GUY]

Originally Posted by whsh93a

I still remember tuning into a CBS program in the late 50's (I think it was a movie) and discovering color on my family's B/W Motorola set. It was there, but pretty dim. As a kid, I always wondered if I was seeing things until I read one day years later that they had conducted experiments to fool the brain into seeing colors on standard B/W sets. It only worked for a percentage of people. I guess I was one of them??

Maybe I'm not remembering correctly (old memories can change and fool the rememberer). Anyone know anything about this?
DH

Yes I remember something like that...At about the same time I was living in OH and we got our stations from Cleveland...Anyway IIRC one the the stations ran some tests for color via B/W sets..It was in the mid to late 1950s.

And if my memory serves me...They were experimenting with a "flicker rate" for each scan line...And for certain "flicker rates" the eye would "perceive color"...

Feel free to correct me...It was a long time ago and I was not very old at the time...

[Steve D.]

Originally Posted by BrianSummers

Hi
you might be interested to know that EMI in the UK had a go at a field sequential colour (UK spelling!) camera. see http://www.tvcameramuseum.org/emi/ex...2/seqcolp1.htm
This was an experimental colour wheel camera using a similar arrangement of 3 CRTs and 3 cameras looking at them, as sort of standards converter. I have a write up on it somewhere but it was much the same as the CBS one.

There were many defects and a lot of electronics to go with it all, but at that time there were not many choices for colour cameras the only good (ish) was the BIG 3 IO option.

Regards Brian S

There was an extensive discussion, 3 years ago, here on AK dealing with the early '50's British color television experiments: British Color Experiments - 1950s mystery photos - AudioKarma.org Home Audio Stereo Discussion Forums
Address:http://www.audiokarma.org/forums/showthread.php?t=76927

-Steve D.