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BELL SYSTEM TECHNICAL JOURNAL 



an infinite starting slope which cannot be provided with the practical limi- 

 tations of frequency band width and power available so that here the actual 

 delay used was chosen as 0.9 H, resulting in evident but acceptable distortion 

 in the display in the area directly beneath the aircraft. Figure 53b indi- 

 cates the fundamental circuit method of generating this wave form. The 

 linear term is generated across the capacitance Co and the series current 

 flowing through the additional elements Ri , Ci and Ri , Co supplies the two 



SWEEP , , 



TUNING J |_ 

 PULSE 



l"'ig. 53. — H}'perl)olic sweep wave form generation — simplified schematic diagram. 



additional exponential voltage wave forms. The resistances Ki and R^ 

 arc required to be variable, their value being determined by the altitude of 

 the aircraft. The i)ractical form of the circuit employed is outlined in 

 Fig. 53c, which includes the additional resistor required to enable mo(lif}'ing 

 the rate of rise of the sweep wave form in accordance with the selected 

 interval of ranges to be displayed. 



2.54 The Sivcep Amplijier 



The remaining portion of the radar sweep circuit is concerned with the 

 amplification of the j)roperly timed and generated sweep wave forms to 



