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3. SOFTWARE 
The software for processing SAR data consists of three steps. The first 
and the third steps are performed by FACOM M-380 (FEP ) and the second step is 
performed by FACOM VP-200 (BEP ) . The process flow is shown in Fig.3. 
FACOM M-380 (FEP) FACOM VP-200 (BEP) 
  
  
  
STEP 1 
&) "| DATA UNPACKING = STEP 2 
SAR RAM DATA 
p RANGE COMPRESSION 
STEP 3 V4 AZIMUTH COMPRESSION 
@-- 
DATA EDITION 
  
  
  
  
  
  
  
  
  
  
  
  
  
SAR IMAGE DATA 
  
  
  
  
  
  
  
FIG. 3 PROCESS FLOW 
STEP} 
This step is performed by FEP. SAR raw data is read from CCT and is 
unpacked to word data. The scene size to be processed is input and the image 
center time is calculated. The parameters necessary for azimuth compression are 
calculated and stored in the shared disks. 
STEP 2 
This step is performed by BEP. The subscene data (15km in azimuth x 20km 
in range) is read from the shared disks. The range and azimuth compression are 
performed in frequency domain. After the azimuth compression the data is 
divided into 4 looks. This 4 looks data is summed to the 4 looks data of the 
neighbor subscene. The corner turning is not performed because 2-dimensional 
data reside on main memory. 
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