13
Installation
IRIDIUM
0514
The table below shows the distance to other Inmarsat
equipment, with and without use of filter.
9505 ISU Protection Distance
Main Lobe
(Metres)
Side Lobe
(Metres)
Back-Lobe
(Metres)
No Filter
14
4
4
Inmarsat (Mini-M)
No Filter
25
4
4
Inmarsat (Std-M)
No Filter
84
20
20
Inmarsat A
No Filter
70
16
16
Inmarsat B
No Filter
14
14
14
Inmarsat C
With Filter
1
1
1
Inmarsat (Mini-M)
With Filter
1
1
1
Inmarsat (Std-M)
With Filter
4
1
1
Inmarsat A
With Filter
4
1
1
Inmarsat B
With Filter
1
1
1
Inmarsat C
2.11 Analogue telephone
The PSTN interface on the transceiver unit converts the
wireless Iridium network into an ordinary telephone line.
You can connect a standard analogue PSTN telephone
directly to this interface for crew calling or as an office
phone.
With a PABX you can add more telephone lines for
multiple phones ie. office network.
The interface handles the following tasks:
•
generates DC current to the phone/PABX in both idle
and active mode
•
generates ringing voltage
•
detects call requests from a phone/PABX
•
detects DTMF tones from a phone/PABX
•
outputs 12 or 16kHz billing tone for a PABX
Important: Do not connect the transceiver to a PSTN
telephone line on land.
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
Ω
+ 750
Ω
// 150 nF (this
impedance also covers 600
Ω
)
Ringing voltage:
60V RMS, 90 Vpp (square
wave)
Ringing sequence:
0.6 sec On, 4 sec Off
Ringing frequency:
30 Hz
Ringing drive capability: 1400
Ω
@ 30 Hz (= 5 normal
ring units)
