The AN/APX-121 transponder represents our first application of our vast experience with legacy systems and all the lessons learned to a new product design. This, combined with the latest technology and manufacturing techniques assures a product that will not only perform to all specified and tested requirements, but will be supportable throughout its life cycle. The AN/APX-121 is one of the highest reliability transponders on the market today with a mean time between failures (MTBF) of 4,400 hours under the extremes of aircraft operating conditions.
AAMSI’s AN/APX-121 transponder is a solid-state, digital design that supports Modes 1, 2, 3/A, C, 4 & 5. Additionally, it will support Mode S (ELS) and (EHS 3 & 4) along with ADS-B. The APX-121 integrates with the 1553B MUX BUS, TCAS via ARINC-429, NSA INFOSEC Applique, KIT-1 INFOSEC, and C-12718/APX RCU. The AN/APX-121 Mode 4 / Mark XIIA Transponder is an improved version of the AN/APX-108. It was specifically designed to incorporate the latest military mandates including Mode S and Mode 4 with growth capability to Mode 5. This modern design eliminates any concern of design or parts obsolescence and provides all new features while maintaining future growth for new requirements such as ADS-B.
The AN/APX-121 offers clear advantages over other transponders. These advantages include a design architecture that minimizes the number of modules, permits organic maintenance down to the piece-part level for all modules, includes a crypto appliqué for easier maintenance handling, incorporates true digital processing of received and transmitted signals, uses a FLASH memory device to store platform configuration information as well as time-tagged fault data.