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BELL SYSTEM TECHNICAL JOURNAL 



filters cut out part of the spectrum, Wdf) may be integrated over the re- 

 maining portion to give the mean square value of the corresponding output 

 current. This idea is mentioned in the footnote pertaining to equation 

 (4.1-6). 



If T' consists of W plus two sinusoidal voltages of incommensurable fre- 

 quencies, say 



V = P cos pt + Q cos qt + TV , 



CONTINUOUS PORTION OF OUTPUT SPECTRUM OF SQUARE LAW DEVICE 



INPUT zz P COS 2nr„t + NOISE 



a-^wjf) 



OUTPUT D,C.= a(_p2/2+p Wg) 

 LET p w2=C 



INPUT SPECTRUM 



INPUT NOISE 



C/2 



c/2 



2f--^ 



• FREQUENCY 



Fig. 8 



2fp+p 



the continuous portion Wdf) of the power spectrum of / may be shown to be 

 (4.5-13) plus the additional terms 



a'Q\w(f - /,) -F iv(f + /,)] (4.5-14) 



where /g denotes q/2ir. 



When the voltage applied to the square law device (4.1-1) is'*^ 



V(t) = Qil + kcos pi) cos qt + Vn 



Ok Ok 



= Q cos qt + ^ cos ip + q)i + '±- cos (p - q)t -f Kv 



the resulting current contains the dc component 



^ <3' (1+ I) + « j[ Mf) df (4.5-16) 



*^ A complete discussion of this problem is given bj- L. A. MacCoU in a manuscript 

 being prepared for publication. 



