[QuadList] RCA Color Tape

[Trevor Brown]

Hi Jonny

I have been following this discussion from the UK

Unless I have missed something  !!!

when you play back VT you get jitter which the TBC fixes in two stages
colour and mono

 

Early machines had no TBC but you can still watch black and white

 

Colour needs correction you cannot decode colour from a jittery signal
(sorry color)

 

The heterodyne fixes this for the colour only part of the signal so you can
decode it

 

but then you have stable colour sat on a jittery black white picture hence
the special record mode to copy the tape.

 

and its 4.43 MHZ over here (even worse)

 

Trevor Brown

TR70 TC100 engineer

 

 

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of John Walko
Sent: 10 November 2009 15:37
To: 'Quad List'
Subject: Re: [QuadList] RCA Color Tape

 

Chris:

Forgive my ignorance, but why was it done this way?  I mean, wouldn't it
have made sense to record at full bandwidth and then playback at full
bandwidth rather than separating it from base band?

 

Did this have something to do with bandwidth limitations with NTSC
broadcast?

 

It never fails to amaze me how complex a piece of machinery a Quad videotape
machine is.  The guys who designed and built these machines were pretty
intelligent.to say the least.

 

Thanks;

 

John Walko

Media Archive Manager

Scene Savers

www.scenesavers.com

800-978-3445

 

From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of
Chill315 at aol.com
Sent: Tuesday, November 10, 2009 8:33 AM
To: quadlist at quadvideotapegroup.com
Subject: Re: [QuadList] RCA Color Tape

 

RCA used direct color for the recording.  Nothing was done to the signal.
It was recorded at full bandwidth to the tape.

 

The playback was where the interesting process took place.  The color was
separated from the base band.  Then in a heterodyne process, the color was
stabilized back to 3.58.  The jitter was removed and then the two were put
back together.  The result was a viewable signal but the color was no longer
locked to the video.  Thus it could not be mixed with another signal or much
of anything else.  This process worked without the servo being locked to
either vertical or horizontal.  That was a unique way to do it.

 

As a side point, if you ever wondered what the "Non Standard" position on
the Colortec was used for, it was used to play back a tape that was copied
from a machine that used the RCA method to stabilize the color.

 

Chris Hill



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