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THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1952 



original picture signal with either polarity and any amplitude, (2) the 

 picture signal delayed by one or two Nyquist intervals with either 

 polarity and any amplitude or (3) any linear combination of (1) or (2). 



Fig. 12 is a block diagram of the experimental set-up used to investi- 

 gate prediction methods that involve previous value and previous line 

 samples such as "planar," etc. The input is fed into a manually variable 

 delay having 0.1 Nyquist interval steps. This delay line acts like a 

 vernier for the 63.5 microsecond line delay. Effectively, it enables the 

 previous line samples to be positioned directly above the previous value 

 samples. 



The 63.5 microsecond delay is a so-called "acoustic" or "ultrasonic" 

 delay line and was developed by Mr. H. J. McSkimin. The associated 

 circuitry was developed by Mr. A. L, Hopper.* Storage is accomplished 

 by a fused silica bar with quartz transducers operating at a carrier 



Fig. 11 — Simplified schematic for "previous value" and "slope" prediction. 



* A. L. Hopper, "Storing Video Information," Electronics, 24, pp. 122-125, June, 

 1951. 



