Milstar Summing Device – Aircraft

The MSD-A provides Milstar Secure Voice Conferencing in support of the National Command Authority mission. A remote MSD feature is available to allow two MSDs to be connected across a fiber optic link. The dual MSD configuration provides a mechanism for remotely monitoring audio and controlling the primary MSD for system redundancy/recovery.

The MSD has four primary functions:

  • Supplements the conferencing abilities of a switch connected to ADI
  • Provides remote access to conferences at another MSD
  • Provides the ability to remote a Call Box from a TAC
  • Provides two RS-422 RCH ports


  • Ten 4W audio channels with adjustable gain
  • Four ADI RS-232 interfaces
  • Six Standard Type II E&M/RS-232 or four SVSA interfaces
  • Five speaker outputs (1W into 8 ohms)
  • Four call box interfaces
  • Two RCH interfaces
  • Front-panel LCD and keypad for local MSD configuration
  • Fiber-optic link for remote output of NET and switch port audio and remote control of local MSD NET ports