Overview

The RA690 Series of CCS equipment provides an all-analogue solution that utilises either distributed facilities or a Central Amplifier with remote Station Boxes for crew interface. The RA690 is extensively used in military and civil aircraft worldwide.

Features

• Modular system design
• Customer specified configuration
• Distributed or central amplifier configurations
• Sub-elements build up individual station capabilities
• Selection of complexity of fail modes available
• Qualified to RTCA DO 160, MIL-STD 704, MIL-STD 810,
  MIL-STD 461/462 & BS3G100

The conventional configuration of distributed amplifiers, filters, and volume controls is designed to ensure the most cost effective performance possible. When configured to utilise a Central Amplifier and remote passive Station Boxes, the single point audio is routed within the Central Amplifier, with selection and control implemented via analogue control lines between these major units. Both architectures are built up using functional blocks to produce a customised configuration for the application required. The functional blocks include Voice Operated Switches (VOS), attenuators, power supplies, muting and intercom override, and interface matching networks.

Facia panel engraving and lighting details (including NVG type), switching and electrical characteristics are configured on each Station Box type to suit the particular requirements of the user.

Additional flexible RA690 system capability is provided by S690 Audio Selector Panels (ASPs) and D690 Switch Boxes. The S690 ASP allows an increase in the number of receiver audio inputs which can be accommodated. D690 Switch Boxes enhance the facilities of the microphone switching, intercom networks and other CCS functions. Varying combinations of Station Boxes, ASPs and Switch Boxes can be installed at each crew position. Where required, the ASP and Switch Box functions can be integrated within the Station Box to form a single unit.

The RA690 Series includes a range of general purpose amplifiers and other units. These include specially designed amplifiers to ensure systems conform to CAA specifications 11 and 15 for Cockpit Voice Recorder and Passenger Address systems. Additionally, existing CCS installation performance can be enhanced with use of units providing noise tracking level control and voice operated switching, and a power supply for active noise reduction headsets.

The RA690 range is further complemented by headset connection Jack Boxes and specially configured Audio Balance Units to ensure a correct interface between the CCS and various Tx/Rx equipments.

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The RA800 CCS is designed to meet present and foreseeable requirements for all aircraft types. The RA800 provides centralised audio control, interfacing to other aircraft systems, and sophisticated intercom networks for the flight crew. It is built on a foundation of intelligent modules, which enables systems to be configured for the particular requirements of the aircraft platform.

The core of the RA800 CCS is the Communication Audio Management Unit (CAMU). All audio routing is contained within the CAMU: this increases immunity to EMI by considerably reducing the volume and complexity of aircraft cabling. Other advantages include ease of installation, weight saving and improved reliability gained through significant cable reduction.

The crew interface to the system is via Audio Control Panels (ACPs) for the control functions. Connections from the ACPs to the CAMU are via digital links. For RA800 equipment, the connection between the ACP and the CAMU is an ARINC 429 bus.

RA800 is microprocessor controlled with centralised CCS with embedded VWS. Where an aircraft is required to undertake a variety of roles, the RA800 system can readily be software reconfigured on board.

The system interfaces to navigation, radio and warning equipment either directly or by means of the aircraft avionics bus (MIL-STD-1553). Sophisticated BIT is carried out within all units that make up the RA800 CCS system. This data is collated and can be sent to the aircraft maintenance system. Voice and/or Tone warnings are produced either from an embedded module within the RA800 CAMU or from a stand alone unit.

AVAD (Automatic Voice Alert Device) is a highly versatile voice alerting system. It stores pre-recorded human speech in digital form and operates under microprocessor control to assemble messages from words and phrases, held in the store. AVAD’s voice is not synthesized and can be in any language, male or female, providing the right degree of stress and urgency for each situation. The quality of speech is so good that the speaker’s voice remains recognisable and highly intelligible even under stressful environmental conditions, such as noisy cockpits and armoured fighting vehicles.

The message priority order, repetition rate and volume are preprogrammed to individual customers’ requirements to give the maximum information to the operator without disrupting performance of his primary task.

AVAD incorporates the benefit of research, conducted by the British Medical Research Council from which psychologically engineered attention tones have been derived and approved by the CAA.

This one compact unit integrates and controls all the voice messages and audio tones required in any complex system. Automatic message priority regrading is available where required recognising the fact that message priorities may vary from situation to situation. The unit may be ‘keyed’ from most types of sensor and will accept a wide range of trigger voltage levels. It also has built-in test and continuous self-monitor facilities for added user confidence.

AVAD can replace all existing discrete audio warnings thus reducing the installation cost and complexity of new projects. It is also simple to retrofit.

Advantages of AVAD

• High Quality human speech
• Faster crew/operator response
• High intelligibility in noise
• Appropriate message emphasis
• Microprocessor control of message format
• Any voice in any language
• Low disruption, noise penetrating attenson tones available
• Message priority sequencing with regrade capability
• Mix of tone and voice outputs
• Continuous self-monitoring
• Simple to re-programme
• Simple, low cost installation

Technical Description

V694
The AVAD V694 is designed to integrate and control audio alerts, be they voice or tone, and is activated by ‘keying’ signals from remote system sensors and/or push buttons. The message format is completely flexible and, for example, in civil aviation circles, AVAD conforms to ARINC 577 ‘Audible Warning System’ and ARINC 726 ‘Flight Warning Computer System’.

Approximately sixt-four seconds of pre-recorded human speech can be digitally encoded and stored as a vocabulary of messages, phrases, words and tones. Messages can be constructed using words and phrases drawn from unit memory under software control, allowing the total duration of all message outputs to exceed the vocabulary capacity by a considerable amount. High quality reproduction is achieved with an advanced digitised speech technique and selective analogue filtering within the unit. Up to 16 message channels offer +ve or OV keying. The unit will respond to single an multiple keys. Four analogue channels can respond to variable d.c. voltage inputs offering a sensitivity of up to 256 logic switching steps across the input range. A stabilised 5 V d.c. output is available for use as a reference for an external potentiometer. Typical variable readouts might be aircraft height, voltages or pressures.

Unit operation and vocabulary store may be defined by the user, (programme software allows control of each message cycle). Each message has Normal, Regrade and Test priority values assigned to it. The output sequence is then controlled by the regrade and test inputs. The audio outpurs are provided: one at telephone/headset level and the other for driving a loudspeaker direct. The nominal level of each output can be set by individual preset potentiometers offering 20dB range with the relative volume of each message or message repeat under the control of operating software. The complete message format, including a repetition rate, pauses, message inhibit/de-inhibit, and tones may be similarly controlled.

A key input is provided which will inhibit any message in progress without affecting other keyed messages. The message thus inhibited would normally remain so until its sensor input is removed and reapplied. Alternatively, the inhibit may be removed after a specified time, if the warning message keyline remains activated during this period.

Full test/reset facilities provide fast checking of unit operation. Correct operation of the microprocessor and amplifier circuitry and control programme status are continuously self-monitored. In the event of a fault condition both audio outputs are automatically inhibited and a ‘fail’ output is provided to activate an indicator to warn of unit failure.

V695
The V695 is a smaller 7 channel unit with microprocessor control offering all the programming flexibility of the V694 and storage capacity of 8 seconds.

V691
The V691 is a single output device ideal for applications where only one warning such as ‘fire’ or ‘pull up’ is required. A second keyline may be used to provide a ‘system enable/disable’ input. The output repeats continuously when keyed.

V696
This unit offers similar facilities to V691 but the message is output once only in response to valid keys.