AS2871 - Audio Console Unit (ACU)
The Envoy is a modular Time Division Multiplexer (TDM) which is easily configured for use in a variety of voice and data applications.
It is ideal for remote voice channel distribution using microwave radio connectivity. It can operate on communication links at rates up to 2Mbps. The chassis houses up to eight individual cards (1 composite card and up to 7 voice/data cards). The unit is equipped as standard with an X21 composite card for line side communications.
Programming of the system is provided for through a standard RS232 port using Hyper-Terminal in VT100 configuration (or similar PC terminal emulator). Connection to line is also made via this card to either X21 or G703. In both cases line speed can be adjusted and bandwidth allocated for various aspects of the system including remote system programming.
The front panel of the unit allows the LEDs from the composite card to be viewed and can indicate which cards have been populated into the system, if there are any alarms currently on the system and also indicate if the link is made between two Envoys.
The Envoy can be fitted with a combination of cards to provide conversion from the X21 or G703 line to FXS, FXO, E&M, V35, X21 etc. These can be fitted in almost any combination to provide a system with great flexibility although some restrictions do apply due to link speed and available bandwidth.