543 
II. Processor Development for Current Missions 
The NASA CV-990 Aircraft SAR flight missions and the SIR-B mission are in 
this category. JPL is currently conducting about two aircraft missions per 
year. There are 10 to 16 flights in each mission and each flight acquires 
approximately one hour of data. The aircraft sensor parameters are listed 
in Table 1. One significant feature of the aircraft sensor is its capability 
of acquiring simultaneous quadruple polarization data, i.e., the vertical 
and horizontal polarizations plus their cross-polarizations upon reception. 
Table 1. NASA CV-990 SAR Parameters. 
  
  
Parameter Value 
Radar Frequency 1225 MHz, 5280 MHz 
Pulse Length 4,9 usec 
Pulse Bandwidth | 449.6 Mz 
Nominal PRF 612. to. 765. tz 
Nominal Altitude 10 km 
Nomina Velocity 200 to 250 m/s 
Antenna Beamwidth 189.(A2),. 809. {Rg} 
Polarization HH, VV... HV. VH 
  
  
  
  
The aircraft SAR sensor is equipped with both optical and digital recorders. 
The recorded raw data are processed by both optical and digital means. 
Optical processing is used for surveying and mapping of large areas. 
Digital processing is applied to selected sites where detailed quantitative 
data analysis is desired. The JPL optical SAR processor has been used 
extensively in the past to support both airborne and spaceborne SAR missions. 
The referenced paper provides a good description of the optical as well as 
digital processing methods used for SAR data reduction. Operational digital 
processing for aircraft SAR data began in the fall of 1983. The processing 
is done on a Digital Equipment Corporation (DEC) VAX 11/780 computer in the 
SAR system laboratory. It applies the frequency domain correlation technique 
for image formation. The algorithm is similar to the one used by the JPL 
digital SEASAT SAR processor, which is based on a Gould SEL computer with 
multiple array processors. 
The software based system offers good flexibility and is producing digital 
10 m resolution 4-look imagery that is especially important to study the radar 
multiple-polarization effect. The drawback of a software processing system 
is in its limited throughput. The current VAX 11/780 computer is equipped