FLIGHT-2 VERSION OF IN-ORBIT TEST TRANSPONDER (IOTT2) FOR ON-BOARD REGENERATIVE SATELLITES

This paper presents the design and realization of regenerative satelli te on-board bypass test equipment. Furthermore, two particular example s of an in-orbit test transponder (IOTT) are discussed in detail. The IOTT1, developed for the first 30/20 GHz ITALSAT satellite (F1), was l aunched in January of 1991. IOTT1 has been a useful tool during satell ite assembly, integration and pre-launch tests. IOTT1 was successfully used to fully characterize the multibeam ITALSAT satellite in orbit. In general, the IOTT functions to bypass the demodulator, the baseband switchboard and the modulator of the multibeam package of the ITALSAT spacecraft payload, providing the ability to fully characterize the s atellite's transponders using well-established IOT test techniques. Th is paper describes and compares the design, fabrication and test of bo th ITALSAT in-orbit test RF bypass transponders (IOTT1 and IOTT2) moun ted on board the ITALSAT multibeam spacecraft, (F1) and (F2), respecti vely. The IOTT1 contains the first MMIC circuitry ever launched into s pace on a communications satellite. The improved IOTT2, fabricated for the second 30/20 GHz ITALSAT satellite (F2), is schedule for launch i n early 1996. These fully space-qualified designs incorporate COMSAT L aboratories' designed and fabricated MMIC K-u-band amplifiers, lightwe ight waveguide K-u-band channel filters and electronic power condition er(EPC) and combined IOTT telemetry/command (T&C) circuitry.