All customer messages, data, and settings are stored in non-volatile memory. As such, after a
power cycle, customer settings as well as any messages that have not yet been transmitted
over the Swarm network will be retained on the Modem. The read/write lifetime of the Modem
memory exceeds 20 years.
4.6 LED Indicators
The Modem contains three indicator LEDs, whose function is described below in Table 14. All
LEDs are off when the Modem is placed into sleep mode.
During the bootup sequence the green LED will be on solid for 3 seconds.
During normal operation after bootup and before shutdown, the green LED will blink
100ms every 5 seconds while the Modem is powered on. This is a “heartbeat”
indication that the Modem is working as expected.
After power is applied until the Modem begins booting, the red LED will be on solid.
After bootup and while the Modem is acquiring a GPS fix, the red LED will flash
quickly until a valid GPS fix has been found. Then the red LED will shut off during
normal operation.
After waking up from sleep, and before a fresh GPS fix has been acquired, there
will be a single red LED flash every 5 seconds (following the green LED flash) until
a fresh GPS fix has been found. Then the red LED will again shut off during normal
operation.
During the shutdown sequence, the red LED will be on solid until 3.3V power is
removed from the board.
The blue LED will be on solid when the Modem is actively receiving from a Swarm
satellite
Table 14: LED functions.
November 2021 Swarm M138 Modem Manual - Rev 1.00 19/77
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