15
Installation
IRIDIUM
0225
2.8 PABX/PSTN Interface
This interface handles and converts 2-wire audio and control signals from/to the PABX into audio and control signals
from/to the LBT. The interface is placed on the control unit BUS, allowing the PABX to act as control unit. The interface
handles the following tasks:
· generates DC current to the PABX in both idle and active mode
· generates ringing voltage
· detects call requests from the PABX
· detects DTMF tones from the PABX
· converts audio TX/RX from the Iridium system to a 2-line balanced signal
This means that an ordinary two-wire system telephone can be connected to the onboard PABX unit/PSTN socket -
and the call can then be initiated from this telephone, e.g. from the captain’s cabin or the cargo control room. The built-
in SMPS of 10-32 V DC generates the necessary current to support the PSTN telephone of the system.
Specification of the Iridium system PSTN connection:
RJ11 connection:
1. nc
2. TIP
3. RING
4. nc
Line Voltage: 48V DC
Line current (source): 24 mA
Line impedance: 270 W + 750 W // 150 nF (this impedance also covers 600 W)
Ringing voltage: 60VRMS, 90 Vpp (square wave)
Ringing sequence: 0,6 sec On, 4 sec Off.
Ringing frequency: 30 Hz
Ringing drive capability: 1400 W @ 30 Hz (= 5 normal ring units)
2.9 Data Interface
The Iridium terminal includes a 9 pol Sub-D connection. The connection is a RS232 interface.
For using this interface, please contact your Iridium Service Provider, that will supply you with Iridium Data Interface
software
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