scope:

This Part 7 contains requirements which are applicable, alone and in conjunction, with other parts of this Engineering Requirement, to the design, fabrication, testing, installation, and field validation of a tower interface subsystem of a CCD/RMM System to be installed and operated in FAA terminal facilities. The tower interface subsystem shall consist of dual facility processing units (FPU's) to provide redundancy for the monitoring of environmental (i.e., weather) and navaid status parameters presently being terminated/interfaced in the tower. Each FPU shall be comprised of a microcomputer, data communications unit (modem), status/control interface, and an uninterruptable power supply. Both FPU's shall continuously monitor the environmental and navaid status parameters. One FPU shall be designated "active" and other "standby". The active FPU shall detect alarm conditions by comparing measured parameters for abnormal state. Upon alarm detection, the active FPU shall notify the central processing subsystem (CPS) in accordance with the ICD Level I and ICD Level II specifications. Upon request from the CPS, the active FPU shall transmit all data available for use at the CPS.