What do the signal light patterns mean on the 4G LTE Base HAT?

I am using a Raspberry Pi 4 Model B with the LTE Base HAT and EC25-A Modem (using the USB cable and QMI connection to establish data). I know that when the modem has a good cellular connection, the blue signal light flashes when there is activity. I have also seen two other patterns of steady flashing that seem to go on for a few minutes at a time: One pattern has the signal light stay mostly on, but flash off every two seconds. The other pattern is the inverse of that – one short flash every two seconds, and off for the rest of the time.

I believe these patterns mean that the modem is searching for a connection, but I would like to know what the difference between the two patterns is.

Hi @pacpurchase,
Thank you for getting in touch!

I hope this helps you.

1 Like