THE RADAR RECEIVER 



767 



ences the over-all system performance is the range of useful brightness avail- 

 able. The extreme variation in the radar response of targets in an area 

 under observation has been discussed previously. The inability of the 

 cathode-ray tube screen to convert this extreme range of electrical signals to 

 a correspondingly large optical brightness range has been a restriction on 

 the performance of military radar systems. Isolated measurements of the 

 useful brightness range available in a cascade screen cathode-ray tube indi- 



Fig. 40. — Typical magnetic focus and deflection coil designs as developed for military 

 radar purposes. 



cates that it is of the order of 10 to 1. The development of the logarithmic 

 video amplifier and "duo-tone" is an attempt to improve this situation. 

 In general this limited useful brightness range of the radar indicator results 

 in a critical adjustment of the operating region of the indicator tube. In a 

 practical military radar system operating under wartime conditions the 

 inclusion of such a critical adjustment always effectively results in a reduc- 

 tion of performance from the optimum achieved in the laboratory. 



2.43 Typical Radar Indicator Component Designs 



Figure 40 illustrates a few typical component designs of magnetic deflec- 

 tion and focus coil structures developed for specific military radar applica- 



