A MULTI-CHANNEL TELEVISION APPARATUS 45 



fo the light sources at the receiving end. The multi-channel scheme 

 described has some advantage in compactness over the equivalent 

 single-channel apparatus, but since it is restricted to narrow angles of 

 illumination of the discs the overall efficiency of light utilization is not 

 essentially different. Comparing now the demands made upon the 

 electrical systems the differences between the two methods are clear 

 cut. Method (1) demands an extension of the frequency range of all 

 parts of the apparatus, the attainment of which depends upon physical 

 properties and technical devices whose mastery lies in the indefinite 

 future. Method (2) demands a multiplication of apparatus parts, and 

 careful design and construction of these parts so as to insure accurately 

 similar operation of a considerable number of electrical circuits and 

 terminal elements. The attainment of the necessary uniformity of 

 performance of the several electrical circuits and terminal elements, 

 while involving no fundamental problems, must present increasing 

 difficulty with the number of channels used. 



