[QuadList] Dropout Compensator (WAS Next Question of the day)

[C. Park Seward]

Bill,

Didn't the Zeus do something similar?

Best,
Park

C. Park Seward
Cell: 818-535-2747
Home: 541-476-6657
2" Quad and 1" "C" transfers
Visit us: http://www.videopark.com




On Mar 22, 2011, at 9:50 AM, Bill Carpenter wrote:

> Hi Park, and everyone,
> 
> The DOC that most folks have never seen is the second generation digital doc which was built for the AVR-3's. 
> 
> It was designed by a great servo engineer, Reg Oldershaw and the man who designed the AVR-3 signal system, "Doc" Hidaka.
> 
> It was a surround sampling device where the 8 points around the dropout are sampled to allow the best possible replacement video
> to be created. 
> So, in the simple example, the dot from the preceding line, one dot before the dropout is sampled, the one directly above the dropout, the next dot, which is still ahead of the dropout by a line, but is to the right on the screen. Next you sample the"dot'' before and after the dropout.
> The you get the three samples of the first line after drop out in the same manner, so you end up with samples from eight points "surrounding" the dropout.
> 
> This is the finest example of a Quad DOC, and really worked well. 
> 
> The two design engineers were the best, and had access to everything that had been done before, and were really having a good time making the greatest DOC.
> 
> I learned something great from this design also.
> When "Doc" was doing a demo for me one day I asked how did he create the dropouts in the tape. I had used a "Xacto knife" to scratch to tape, when I tested the 3M Mincom system that they built for Ampex and was available for the VR-7800.
> 
> This was a way  to create a dropout and cause permanent damage to a tape.
> 
> So, when I asked "Doc" the question he handed me a short section of a rubber magnet out of a Refrigerator gasket which was cut to a point.
> 
> He told me to just hold it against the tape and you would erase a small section of tape wherever the magnet touched the tape.
> 
> The value of this method is no permanent tape damage!!!
> 
> This very smart & very practical engineer is a good friend and he is still active in the TV industry.
> 
> Bye for now, love to all, Bill & Ginger (whoof...whoof)
> 
> --- On Tue, 3/22/11, C. Park Seward <park at videopark.com> wrote:
> 
> From: C. Park Seward <park at videopark.com>
> Subject: Re: [QuadList] Dropout Compensator (WAS Next Question of the day)
> To: "Quad List" <quadlist at quadvideotapegroup.com>
> Date: Tuesday, March 22, 2011, 9:02 AM
> 
> I think most DOC operated the same way. It has an RF sensor to determine a dropout, which is a lack of RF. It took the preceding video line and placed it where the RF was missing. Some DOCs put white or black and others put video while still others placed correctly phased video. With most average pictures, you have a hard time telling it was corrected. Usually the beginning or end of the line had some distortion and that was a tip off.
> 
> I have a couple of the 3M DOCs and they are will made and work well.
> 
> Best,
> Park
> 
> C. Park Seward
> Cell: 818-535-2747
> Home: 541-476-6657
> 2" Quad and 1" "C" transfers
> Visit us: http://www.videopark.com
> 
> 
> 
> 
> On Mar 22, 2011, at 8:33 AM, Sammy Jones wrote:
> 
> > Chris Hill wrote:  
> >> The 3M division was Mimcom.  They made the drop out
> >> compensator for  the 
> >> Ampex machine that did the really good job of inverting the
> >> Chroma and  making 
> >> the drop outs invisible.  Loved it after they put in
> >> the test  circuit.  No 
> >> longer needed a special tape.
> > 
> > This sounds fascinating.  Since I've never operated Quad myself, I'd love to hear more about how various dropout compensators in Quad worked...
> > 
> > Sammy Jones
> > Georgia Public Broadcasting
> > 
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