I'lciiKii ih'.ixsMissiox orr.R ii:i.i.i'iii>\n i.ims 



iw 



with the first, aiul thi- vaniiim tiitic mocluhuor in nirii to ii. The 

 relationship between illuniinalioii and current in the |)h()l()eleclric 

 cell is, as shown in diagram No. 1, linear from the lowest to the highest 

 values of illunuti.ition. The vojiaije-currcnt (/•'. \-er-us /) ciiaracler- 



^l- 



T . T 



SYNCHRONIZING CHANNEL FILTER 



PICTURE CHANNEL FILTER 



1 1 1 1 r 



4 8 IZ 16 20 24 28 32 3G 40 

 FREQUENCY- HUNDREDS OF aCLES PER SECOND 



Fig. 12 — Circuit st-heniatics lal)Ovc) and attenuation characteristics (l)clow) of 

 picture (full line) and synchronizing (dashed line) channel filters 



istics of the amplifying lubes and the modulating tube circuits are 

 shown in the figure by the diagrams which lie immediately below 

 these tuljes. They are not linear o\er their whole extent. It 

 becomes necessiiry, therefore, in order to preserve the linear char- 

 acteristic, which is essential for faithful picture transmission, to locate 

 the range of \-ariation of current in each of the latter tubes on a linear 



