1.0 



0.8 



0.6 



0.4 



0.2 

















.^y 



?? 



//" 



^ 















A 



// 



y 



/ 















/ 



y 



// 



/ 















/ 



'/ 



7 



// 



/ 







Ma 









. 



h 



7 



/ 













> 





, 





/ 



. / 



1/ 



// 



f 









1 A 





/ 



/ 







/ 



/ ' 



■y 







/ 



^ 



'/ 



7 



/ 















/ 



/ 



A 



// 



f 





















/ 



/ 



/ 



/ 



/ 







- 256 







^ ' 









y 



{/ . 



y 



y 















6 7 8 9 



S (in dB/pulse) 



10 



12 



13 



Figure 3. Single-scan detection probability vs required SNR, where the final 

 resolution remains constant but the coarseness of the stage-A bins varies. 

 Rice distribution; N = 1.2, optimum Ng for each M^ for Pq = 0.5; FAR = 

 3 PRF X Ma Mb x 10"% where M^ Mg may vary. 



The case of a single range bin in stage A will be treated in detail since 

 (1) the detection zone to be searched by a two-stage system will in some applica- 

 tions be sufficiently narrow radially that the pulse length necessary to bridge it 

 with a single range bin is not inefficiently long, and for these applications M^ = 

 is optimum; (2) from the analysis of the M^ = 1 case, many general conclusions 

 can be drawn concerning the nature of two-stage systems having any M^; and 

 (3) it is the simplest case to analyze. 



N and the Average Scanning Rate 



The average scanning rate in revolutions per minute for a two-stage 

 system is 60 x PRF / (no. of beam positions) xN when no target is present and 

 is approximately that when the target density is low. Suppose first that the PRF 



16 



