DETECTION OF TWO MODULATED WAVES 



11 



From Figs. 1 and 4 it is to be noted that when m = M the frequencies 

 {q rb u)l2-K are the largest components of the displaced side band 

 interference if a straight line detector is used and have the same 

 amplitude as the {p ± «)/27r components if a square law detector is 

 used. When m > M the q ± u group is much more important than 

 the p dz u group as is evident from Fig. 2. When M > m the 5 rh w 



10 



.001 



.0001 



.001 .01 



/^= RATIO OF CARRIER AMPLITUDES 



Fig. 4 — Relative amplitudes of undesired frequencies as a function of the ratio of 

 the amplitudes of the desired and the interfering carriers. Modulation of both 

 stations large and equal. 



group is less important but this case is of no great interest for if the 

 stations are transmitting identical programs, with similar degrees of 

 modulation, it cannot occur and if the programs are different then the 

 interference is determined primarily by what happens when m > M. 

 Consequently we may consider that the q ± u group constitutes the 

 most important part of the displaced side band interference except 



