The ACI 757 Voice Communications and Control System (VCCS) is a solid state, modular, and flexible system which hasprovided reliable ATC communications for over twenty years. The basic premiseof the design is to provide the Air Traffic Controller with a functionalsystem tailored to his needs. The system provides the controller with singlebutton selection of radio channels for transmit and receive. It also provides'monitor only' as well as headset and/or microphone loudspeaker functions.Use of intercoms, hot line, and airport telephone access are also partof the system. Channel selected and channel in use are readily visibleday and night. Interposition lockout is available to prevent two operatorsinadvertently using the same radio channel at the same time. Incoming RFsignals are visually and audibly apparent with the frequency displayed.

The following is a list of the 757VCCS sub-systems.

  • Radio Channel Control
  • Intercommunications
  • Telephone
  • Crash Alarm & Control
  • Clock
  • Test Unit
  • Power Supply
  • Meteorological


The 757 MD, a microprocessor controlled voice communicationcontrol sub-system (VCCS) integrates the radio, the telephone circuits,the intercom circuits, the hotline circuits, the PABX and switched publicnetwork circuits to provide a fully integrated voice communications system.The parameters and configurations can be custom tailored in the field,via the electronic technician's system monitoring and control console,to the customer's needs and requirements.

The VCCS is modular and easily expandable. Plug-inmodules are used to facilitate maintenance and replacement of modules.The VCCS consists mainly of four parts: position electronics, a centralelectronics, remote intercom units, and an electronic technician's systemmonitoring and control console.

The VCCS relies heavily on the distributed processingapproach. Micro controllers in different cards and modules relieve themain 32 bit microprocessor in the central electronics unit from repetitivetasks. Each microprocessor circuit has built-in self test facilities

The 757MD Air Traffic Communications Control Systemintegrates various sub-systems necessary to provide the operators withaccess to all the required communication links and to enable the operatorsto monitor the system status.

The 757MD Radio Channel Control Sub-System providesthe operator with the controls to select, transmit and receive (monitor)all radio channels available to the position. Selection of channels isby pushbutton; PTT is by microphone, headset or foot switch. Audio to modulethe transmitters is by hand microphone or by headset. Monitoring is byheadset or loudspeaker. To enable the operator to conduct his/her workefficiently the system is equipped with indicator lights, warning lights,buzzers, and the means of eliminating inadvertent interference by otheroperators.

The 757MD Intercom/Telephone Sub-system providesthe air traffic control operator with the means of communicating directlywith other parties through operating pushbuttons and other controls onthe console. Telephone communication is by headset or handset. (Other systemconfigurations are possible.)

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