Line Input/Output c/w PSTN Interface
The DDCS can be configured to provide one or more telephone interface channels.
These channels are integrated as the centre channel in a 3-channel line I/O module in the System Chassis (typically only one interface would be installed per system) that needs to connect to the host vessel phone system.
Note that the telephone interface uses a standard ‘subscriber loop’ analogue interface circuit – similar to a standard domestic telephone. Tone dialling is used, and the vessel telephone system should be fitted with a suitable interface for this functionality.
The purpose of the telephone system is to allow (for example) chamber occupants to talk via the vessel telephone system to people onshore (doctors / family members etc), using the DDCS comms headset from the chamber – and benefiting from the use of the helium speech unscrambler.
The telephone channel adjustment / configuration screen is shown by pressing the title tile for the phone channel as shown on the image. This screen has familiar fader controls to adjust the transmit and receive levels for the telephone interface. Once set correctly, these should not require adjustment.
Operation of the telephone is the same as using any standard phone. The supervisor dials the number to call (the number entered is displayed) or selects a previous number from the list, and then the ‘Call’ button is pressed to take the phone circuit ‘off-hook’ and make the call.
If the vessel telephone exchange requires an outside line digit to be dialled first (e.g. ‘9’), this should be entered at the start of the number.
Normally the supervisor will dial the number and initiate the call with the third-party. This is done by the supervisor placing the telephone channel on a bus in round-robin mode and selecting himself to talk & listen to that bus. The supervisor can then talk to the party being called and handle the transfer to the diver in the chamber.
To connect the diver to the third-party, the supervisor simply places the diver’s chamber headset channel on the same bus as the telephone channel. Once the call is underway, the supervisor can leave the call by de-selecting himself from the bus.