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expert system in diagnosis is that new appearing errors can be analysed by 
finding the belonging causes and adding the results to the knowledge base. 
According to [Hayes-Roth, 1983] the ideal expert system consists of several 
components. In that definition the knowledge base comprises the facts and 
the rules. These rules have to be seen as the active part of the knowledge 
base because they will be subject to the interpretations performed by the 
so called rule interpreter. 
Debugging means the application of proven recipies to analyse malfunction 
situations. It incorporates the facts about the system design and behaviour 
and assumes the capability of forecasting. Debugging procedures shall be 
applied to image quality related procedures, machine malfunctions or soft- 
ware problems. Whenever problems with a product are observed either by the 
operator or automatically, the rule interpreter looks through its rule system 
using backward chaining methods in order to find the cause of the problem. 
A representative application of this method can be found in [Fikes, 1985]. 
As a result of the debugging procedure there will be given a set of 
instructions which can be performed automatically or by operator selection. 
It is therefore an application of diagnosis and debugging subsystems of the 
expert system. 
4. AN EXTENSION TO SOFTWARE ENGINEERING 
Because of the complexity of the software system it has been decided to apply 
a phase model to the software development. There will be involved a lot of 
engineers and programmers working on different modules for various hardware 
architectures. In order to meet that high requirements ADA! was selected 
for the implementation. 
During the past years there have been encountered a lot of problems running 
operational and development jobs in parallel. Therefore, the software will 
be developed on a dedicated software development environment using SUN-3? 
workstations. 
Very big parts of the system can be developed, tested and debugged solely 
within the workstation environment where the user takes full advantage of 
window technique, bit map display and powerful CPU. The completed program 
can then be transferred to the Front/End machine over the network. 
Among other expert system tools KEE* (Knowledge Engineering Environment‘) 
has turned out to be a promising instrument for the realization of the 
intelligent SAR processor ISAR. It can be looked at as a specific programming 
language dedicated for the machine realization of knowledge and inference. 
The representation of that knowledge is done using a frame based language. 
  
!) ADA is a trademark of the Department of Defense 
2) SUN-3 is a trademark of SUN Microsystems 
3) KEE and Knowledge Engineering Environment are trademarks of IntelliCorp 
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