Health Monitor Analysis System: Successful Instrumented Design and Unexpected Benefits

The U.S. Air Force needs to extend the life of their AN/GPN-22 and AN/TPN-25 precision approach radar (PAR) systems. Obsolescence issues plaguing many PAR transmitter components, along with the need for specialist diagnostic teams, prompted a redesign effort of the transmitter sub-system. The current PAR family design provides limited analog Built-in-Testing and manual test points for diagnostic measurements. Our transmitter redesign effort includes the health monitor analysis system (HMAS), a microprocessor based transmitter management subsystem (TMS) that provides health monitoring. The TMS automates maintenance health diagnostics, prognostics and transmitter alignments. All transmitter system Line Replacement Units (LRU) are fully instrumented: inputs, outputs, and critical internal parameters. The TMS contains a Diagnostic Engine that will fault isolate to an individual LRU. Extensive instrumentation provides high confidence of data measurements. All instrumented parameters are logged to a database for empirical prognostic analysis. In order to reduce the specialist training needed for the diagnostic teams, the TMS contains a user friendly graphical user interface (GUI). A transmitter traveling wave tube (TWT) prognostic engine autonomously performs a Miram Curve [1] analysis to determine optimal tube filament parameters to extend tube life and computes tube life estimates. Except for catastrophic failures, this will allow for tube replacement during scheduled maintenance, minimizing system downtime. A Prognostic Engine by-product is TWT potential life extension due to optimal tube temperature management. Other potential applications for the TMS framework include any instrumented electronic system where health monitoring is desired. The TWT Prognostic Engine is directly transferable to other vacuum-electron device based radar and communication systems.