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  #31  
Old 10-06-2016, 08:30 AM
kf4rca kf4rca is offline
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As I recall, the vir switch had its own set of controls. So, you could make it look like anything you wanted.
Those vir generators are all over Ebay if you wanted to play with one. Except for the VITS100, they also have a full field test generator with a boatload of test signals. The one I liked was the Tektronix 1910.
I've seen them as low as $30.
But I think the vits deleter and inserter section could be used in eradicating copyguard thats in the vertical interval.
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  #32  
Old 10-16-2016, 11:41 PM
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As i recall, it did have internal color and tint adjustments for VIR, and manual adjustments for non Vir mode.. If i remember correctly, it performed well most of the time, but there were times when we had to disable it because it didnt agree with all programs...

SR
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  #33  
Old 09-28-2017, 11:04 AM
kf4rca kf4rca is offline
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Here is the only 19" GE VIR set I've ever seen. I think most people bought the stripped down model despite the massive advertising campaign.
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File Type: jpg GE_VIR_SET_WCBD.jpg (52.4 KB, 21 views)
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  #34  
Old 09-28-2017, 11:19 AM
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A friend of mine owns a VIR set with a gassy CRT.
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  #35  
Old 10-01-2017, 04:42 PM
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I got a VIR-equipped Electrohome console from 1978 just yesterday. It starts but I'm sure it'll need work. Good thing I got the manual, and saw this thread, otherwise I still wouldn't know what it is.
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  #36  
Old 02-20-2018, 03:58 PM
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I think I've solved the problem for RCA's original NTSC spec with a better implementation:
Just have colorburst for almost a whole line period in the last serrated segment of the field sync pulse
at ~50% luminance level(like GE-VIR) (picture level of light complexions.)

This gives nice clean, long duration subcarrier reference every sixtieth of a second (like VIR) (no burst every line needed)(who gives a flip about airplane-flutter.)

Then 1950s era receivers simply run separated vert sync thru a HPF to obtain subcarrier phase reference (no countdown circuit chips required 1970s VIR)
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  #37  
Old 02-20-2018, 04:20 PM
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Quote:
Originally Posted by NewVista View Post
I think I've solved the problem for RCA's original NTSC spec with a better implementation:
Just have colorburst for almost a whole line period in the last serrated segment of the field sync pulse
at ~50% luminance level(like GE-VIR) (picture level of light complexions.)

This gives nice clean, long duration subcarrier reference every sixtieth of a second (like VIR) (no burst every line needed)(who gives a flip about airplane-flutter.)

Then 1950s era receivers simply run separated vert sync thru a HPF to obtain subcarrier phase reference (no countdown circuit chips required 1970s VIR)
Do you mean a different version of NTSC with subcarrier reference only in the vertical segment but not in each line?

1) Does not solve the problem of having it re-inserted in order to meet FCC signal specs. The original problem was in good part due to the locally reconstituted sync and burst having the wrong phase and amplitude compared to what had happened to the chroma coming over the network. Simply passing the degraded burst to the transmitter was a non-starter, as it could cause problems with color killers in receivers.
2) Not possible to use it with affordable crystal oscillator / phase-locked loop technology, since the oscillator in the receiver would need to have a free-running frequency within 30 Hz of correct, or side-lock could occur. With burst on every line, the free running crystal needs only to be within half that, or 7867 Hz. To insure quick lockup, the oscillator actually should be off no more that 10% or so of the nearest sideband and the loop bandwidth should be just wide enough to pass a beat frequency. Remember, horizontal rate sidelock is what was used in gated-rainbow color bar generators. This proposal would allow accidental vertical sidelock, and would require a crystal oven for stability and/or a customer color lock control to prevent it.

A very thorough theoretical study was done of the color burst to verify that once per horizontal was the right way.
http://ieeexplore.ieee.org/document/4051510/
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