DETECTION OF TWO MODULATED WAVES 9 



numerous as there will be a product of the .l/'s with each of the ms. 

 However, these are of even moderate importance only when the 

 modulations of both stations are high, and a square law detector is 

 emplo\'ed at the receiver. 



Hence we may picture the interference as made up chiefly of dis- 

 placed frequency spectra of the type mentioned above, of a carrier 



.001 



.0001 



.001 -01 



/erratic of carrier amplitudes 



Fig. 2 — Relative amplitudes of undesired frequencies as a function of the ratio 

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

 station small and of interfering station large. 



beat and of the interfering speech, which is weak but important because 

 of its intelligibility. The results in the case of a straight line detector 

 would not be very greatly different. The frequencies of the type 

 (p db 2 zt u)lliv would be negligible, the two spectra derived from 

 p ± u would be much less important and certain new, but rather small 

 cross product frequencies would appear. 



