THE RADAR RECEIVER 



789 



the magnetic deflection circuits must be carefully considered in the over- 

 all radar receiver design, if the display is required to reproduce short-range 

 information. In such cases, it is customary to insert delay networks in the 

 video channel introducing a delay to the received signal equal to that present 

 in the indicator deflection system, or to "pre-pulse" the deflection circuits 

 prior to the time of the outgoing radar pulse. 



It is desirable from a power consumption and display appearance stand- 

 point to limit the range deflection of the radar indicator only to that ampli- 

 tude required to adequately fulfull the display requirements. A method 

 commonly employed is indicated in Fig. 57. Here a measure of the current 

 flow through the deflection coil, and accordingly the amplitude of the de- 

 flection of the cathode-ray tube beam upon the screen, is obtained from the 

 feedback voltage of the sweep amplifier. This voltage is impressed upon a 



INPUT (FROM SWEEP- 

 AMPLIFIER FEEDBACK 

 RESISTANCE) 



TT 



STOP- PULSE 



OUTPUT 

 (TO SWEEP 

 MULTIVIBRATOR) 



--SWEEP- AMPLITUDE 

 CONTROL 



Fig. 57. — Range sweep stop pulser circuit for limiting sweep deflection. 



"sweep-stop" pulser which upon rising to a preselected value corresponding 

 to the desired sweep amplitude is caused to trigger this circuit. The output 

 pulse of this circuit is then employed to operate the sweep limiter portion 

 of the sweep timing multivibrator previously described, thus terminating the 

 sweep timing pulse proper. 



2.6 Circuits for Radar Range and Bearing Measurement 



In this review of radar receiver design principles only the presentation of 

 the received radar signal in a form convenient to the observer has been 

 considered. To fully utilize the complete radar information available, 

 determination of the complete coordinates is necessary with an exactness 

 which is determined by the specific use of the data and by the capabilities 

 of the radar system itself. This section will be devoted to a review of the 

 methods employed to generate electronic markers necessary for the deter- 

 mination of range and azimuth and elevation angles. These markers in- 

 clude both the fixed variety, whereby the approximate coordinates of a 

 radar target can be determined by inspection, and steerable markers by 



