294 GENERIC TYPES OF RADAR SYSTEMS AND TECHNIQUES 



Type of Information. In any radar system problem there are two 

 basic kinds of target information: 



(1) The desired ra.da.r-denved target information 



(2) The radar-derived target information that is actually obtained 

 using a given system 



The latter will be exemplified by answering the last three questions posed 

 at the beginning of this paragraph. 



Most commonly, the desired radar-derived target information takes the 

 form of a four-dimensional information matrix as shown in Fig. 6-1. The 



Expanded View of a 

 Quantized Region 



I^i Elevation 

 rBeamwidth 



Azimuth 

 leamwidth 



Range Resolution 

 Element 



'^MAx=Max. Unambiguous Range 

 i/^s = Solid Angle of Coverage 

 N, =No. of Range Elements 

 No =No. of Azimuth Elements 

 Ne =No. of Elevation Elements 

 Nv =No. of Velocity Resolution 

 Elements Per Block 



Fig. 6-1 Radar System Information Matrix. 



radar is expected to detect and classify targets according to their range, 

 their angular orientation (two dimensions), and their relative radial 

 velocity. Depending upon the tactical problem, each dimension may be 

 characterized by (1) a maximum and minimum value, and (2) a minimum 

 resolution element. Thus, the total amount of information which the radar 

 may gather is 



A^ = A^, X A^« X A^a X A^. elements. (6-1) 



Generally, the tactical problem sets some limit on the time taken to 

 gather this information. If we define this as the lota/ scanning time, tsc, the 

 required interrogation rate of the radar system is 



N = N/t,c elements/sec. (6-2) 



Often, it is quite informative to translate a system requirement into the 

 form of Equations 6-1 and 6-2. For example if we consider a system which 

 requires 150 n.mi. range with 0.1 n.mi. resolution; a 1° fan beam with 360° 



