Iridium Communications Inc.
Information Contained in this Guide
9602 SBD Transceiver Product Developers Guide is Subject to Change Without Notice
Revision 4.0
Iridium Communications Inc.
Distribution of Guide Restricted
Proprietary & Confidential Information 24 to Product Developers Only
and 9522B)
Existing antennas will require different RF connector types to than those for the 9601, 9522, 9522A
and 9522B
4.3 GPS Connector
The second RF connector, labeled “GPS” in the board silkscreen, is a pass-through connection from the
antenna path and is provided for GPS receivers that wish to share the main antenna. An overview of this
circuit is provided in Figure 7. The following operational points should be noted when using GPS
receivers connected to this point.
o
The GPS pass-through path is activated by detecting the presence of a DC voltage on the center-
pin of the GPS connector. The 9602 uses the voltage from the GPS center pin to switch on the
RX path and requires minimal current (<100uA). The GPS path activated when this center-pin
voltage is higher than 1.2V.
o
There is a path loss of approximately 3dB in the receive direction from ANT to GPS.
o
The GPS receive path is temporarily switched off during transmissions from the 9602.
o
As long as the 5V supply to the 9602 is connected and the DC voltage on the GPS connector is
present, the GPS pass-through path is made available. The GPS path is available even when the
9602 module has been turned off using its ON/OFF control signal.
o
If the GPS port is not used it may be left un-terminated with no adverse effect.
o
The GPS receiver must present 50 ohm impedance across the Iridium band or SBD performance
could be degraded.
o
The output return loss is typically -8 dB.
Figure 7:
Equivalent circuit for GPS connection when GPS path is active and 9602 is not transmitting
