Globalstar ST100 User Manual page 11

8545-0194-01 v1.0
Messages are composed of 1 or more 9-byte payloads. The user application may send a message via the Bluetooth Low Energy
interface to the ST100 board from 1 to 144 bytes in length. The ST100 board will break the message into 9 byte packets. A 144
byte message would be divided into 16 packets.
There are brief periods of time where there is no satellite in range of the commercial IoT transmitters due to obstructions
and/ or satellite coverage geometry. Since a commercial IoT device has no way of knowing if a transmitted message has been
successfully received, the ST100 Board is designed to send multiple (redundant) transmissions for each message 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
ST100 Board will normally 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 interval with a configurable maximum and minimum duration.
The default re-transmission configuration occurs between 5 to 10 minutes apart for each even randomized distribution. 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.
ST100 User Manual v1 Confidential & Proprietary Information 4