SEM Electronics
Instrument
Command and control, redundancy management, engineering data collection, and on board servo control functions are contained in the Actuator Drive Module (ADM) which interfaces with the spacecraft via a MIL STD 1553 bus. A radiation tolerant imbedded processor (Harris RTX 2010) is used for command and control functions with program code primarily written in C and operated out of RAM. Instrument redundancy management to the circuit card level is via ground command of a series of 96 relays, the drivers for which are packaged in hybrid form to minimize circuit area. Scan mirror control uses a digital servo to provide a programmable 2-speed, 2.67 s rotary scan cycle with less than 0.8 mrad error over the 2 sec, 100 ground scan segment.
