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Originally Posted by kf4rca
Are those 8 bit units? TBC's and Frame Sync's are either 8,9, or 10 bit. That has to do with quantization of the signal. Eight bit units chop the analog signal into 256 levels before dumping them into the memory. Nine bit units are 512 levels and 10 bit units 1024 levels. More bits require more memory but give a cleaner picture. The only 10 bit units I ever knew of were Sony and Tektronix. CNN had a Sony 10 bit unit when I was there. It took up about a foot of rack space.
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The noise from just about any VT replay is sufficient to act as a dither signal for an 8 bit TBC. Adding extra bits then makes negligible difference.
A historical note on video analogue to digital conversion. This set the limit of what was feasible for digital video systems. High speed memory was expensive but much less of a problem. Converting video to digital used to be a very complex and critical board full of components. 8 bits was the limit of what could be done. Then TRW introduced the TDC1007. 20MHz sampling, 8 bit resolution. It was in a monstrous 64 pin ceramic DIL package and cost several hundred $$$. But it did the job in 1 chip and was used by Quantel and many others in pioneering digital video processing systems. It even won an Emmy award, such was its importance.
Knowing TRW's background in military and aerospace I wouldn't be surprised if it was first developed for military radar. The TV usage might well have been secondary.