8545-0198-01 Revision 1.9 STX3 Users Manual
9/24/2020 Globalstar, Inc. Confidential and Proprietary Page | 3
Messages are composed of 1 or more 9-byte payloads. The STX3 can only transmit 9-byte on-air messages, so user payloads greater
than 9 bytes will require multiple on-air packets to be transmitted for each user payload.
There are brief periods of time where there is no satellite in range of the simplex transmitters due to obstructions and/or satellite
coverage geometry. Since a simplex device has no way of knowing if a transmitted message has been successfully received, the STX3
device is designed to send multiple (redundant) transmissions for each message being sent over the Globalstar network. The default
value for the number of redundant transmissions per message is 3. This means that each message sent to the STX3 will be
transmitted 3 times. Each transmission will contain the exact same data payload. The redundant transmissions of each message will
be sent on a randomized 5-minute nominal interval.
The transmission sequence for a single-packet message using the default setting of 3 redundant transmissions is shown below.
The transmission sequence for a two-packet message using the default setting of 3 redundant transmissions is shown below.
For normal conditions where the transmitter has an open view of the sky, this will result in a better than 99% chance that the
message will be received.
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