A Distributed Software Correlator at the Rapid Prototyping Array

The Rapid Prototyping Array (RPA) is a toy radio telescope located 30 miles from U. C. Berkeley in Lafayette, CA. It serves primarily as a software development test bed for the Allen Telescope Array (ATA). We have developed a minimally functional prototype of the ATA control system founded on C++, Java, and a CORBA-based distributed architecture. The system controls RPA pointing, electronics, and data processing, culminating in a real-time software correlator (i.e. an imaging system). This system has helped us characterize our preliminary design of the ATA control system. Overall, the distributed architecture provided successful, versatile control supporting a wide range of experiments from satellite tracking to beam characterization to celestial observation. However, some weaknesses in the CORBA communications layer were identified, and the synergies of mixing C++ and Java were balanced by paradigm mismatch between the languages. We learned that Java was as fast as C++ and supported more ready-made libraries. Based on these experiences, we changed our design to eliminate CORBA and build a pure Java system at the ATA, which is now under development.