388 



THE RADAR RECEIVER 



j^i:^ 



Eexn(-af) 



Fig. 7-15 Pulse Lengtheners. 



The output spectrum of the lengthener for the case where a = 0, and 

 T = Tp IS given by 



\fF;\ = 1+ 2m sin ^ \Ar cos (co./ + <A) - ^1 



r/ 27r\ ^ , ^ , U)mTp~\ 



+^.s, 



[(-4:)-' 



+ <^ + 



Tp 



UmTp 



(7-42) 



^m + 



Tp 



When the output from the lengthener is passed through a low-pass filter, 

 the first term becomes the only significant term in the output if the period 

 of the modulating signal is much greater than Tp. If the low-pass filter has 

 a cutoff frequency Wc, outputs are also obtained for modulation frequencies 

 satisfying 



1 P 



(7-43) 



7-18 CONNECTING THE RECEIVER TO THE RELATED 

 REGULATING AND TRACKING CIRCUITS 



The receiver must provide signals to range or speed error detectors, and 

 angular error detectors. It is desired that the outputs of these detectors 

 have a stable characteristic with time and with input power level to the 



