User Guide

Iridium Communications Inc. Information Contained in this Guide
9602 SBD Transceiver Product Developers Guide is Subject to Change Without Notice
Revision 1.2 (DRAFT 2)
Iridium Communications Inc. Distribution of Guide Restricted
Proprietary & Confidential Information 27 to Product Developers Only
3.3.4 Serial port signal levels
3.3.4.1 Data Port Inputs
The inputs on the 9602/9602N serial port (RTS, DTR and TXD) will operate correctly at 3.3V digital signal
levels.
RS-232 interface chips can be fitted to the host system motherboard if connection to an external RS232
link is required. Note that these may invert the digital logic level, so another inversion may be required.
3.3.4.2 Data Port Outputs
The five outputs from the 9602/9602N serial port (DCD, DSR, CTS, RI and RXD) are all at 3.3V digital
levels.
3.4 Hardware Failure Reporting
If the 9602/9602N detects a hardware problem during initialisation, the 9602/9602N may be unable to
function correctly. The 9602/9602N notifies the DTE of this situation by issuing an unsolicited result code
at the end of initialisation:
HARDWARE FAILURE: <subsys>,<error>
where <subsys> identifies the software subsystem that detected the error, and <error> is the
subsystem-specific error code.
Any AT commands that cannot be handled in the failure condition will terminate with result code 4
(“ERROR”).
3.5 Network Available Output
This is a digital output that can be used by an application to know when the transceiver has visibility to the
satellite network. This is useful in applications where the transceiver may move around terrain that
reduces the amount of time that clear line of sight to the satellite constellation is available. The Product
Developer can use this output to preserve battery life by reducing the number of attempted transmissions
by including this logic output in the application decision logic.
Network Available means only that the 9602/9602N can successfully receive the Ring Channel, or, put
more simply, it can see an Iridium satellite. Network Available is not a guarantee that a message can be
successfully sent. The Network Available state is evaluated every time the Ring Channel is received or
missed. If the Ring Channel is visible, then that is typically every 4 seconds. If the Ring Channel is not
currently visible, then the update period can be as long as 2 minutes, depending on how long the lack of
satellite visibility existed. This is because the 9602/9602N attempts to conserve power by increasing the
ring search interval while the satellites are not visible. Every time a ring search fails, the time to wait is
increased and eventually limits at 120 seconds.
If Network Available is currently off, the Field Application may still attempt an SBDI[X] session. This will
force the 9602/9602N Transceiver to look for the Ring Channel immediately, and on finding it, to attempt
to send the message. In this case Network Available will not come on immediately. The Network Available
does not turn on while in a +SBDI session. It will however turn on 4 seconds later assuming that the Ring
Channel is present. After the SBD session completes, the 9602/9602N performs a new Ring Channel
search sequence, at the end of which Network Available gets turned on. That can take between 4 and 12
seconds.