6-6J 



PULSED-DOPPLER RADAR SYSTEMS 



325 



Thus, to achieve the same useful power return from the target as for a CW 

 radar of average power P, the peak power of a simple pulsed-doppler system 

 must be 



Pt = P/d\ (6-35) 



and the average power must be 



Pa,, = P/d. (6-36) 



The average power governs the weight of the power source and the peak 

 power dictates the voltage breakdown requirements of the transmitting 

 system components; thus these factors must be weighed against the 

 duplexing difficulties of a CW system. 



One of the most common applications of the simple pulsed-doppler 

 system is for doppler navigation radar systems. This will be described in 

 Chapter 14. 



Range-Gated Pulsed-Doppler Systems. The full benefits of a 

 pulsed-doppler system can be realized by range-gating the receiver. This 

 technique permits range measurement with the resolution inherent in the 

 radar pulse width and it can also improve the signal-to-noise ratio and 

 signal-to-clutter ratio by the reciprocal of the range-gating duty cycle. 



Master 



Frequency 



Control 



Pulsed 



Coherent 



Transmitter 



Target Doppler Bandpass 



Filter Composed of Continuous 



Narrow Band Filters 



fj (Velocity) 



Fig. 6-25 Gated Pulsed-Doppler System with Means for Range Measurement. 



