4G四, 21/01/2021 - 17:27 的修訂版本





HW: 4G-AC68U

ifconfig usb0

cat /sys/class/net/usb0/statistics/rx_bytes

Modem: /dev/ttyACM0


Signal strength


/usr/sbin/modem_status.sh signal

1    Marginal.
2    OK.
3    Good.
4    Excellent.
5    Full.


Signal strength by command



chat -t 3 -e '' 'AT+CSQ' OK >> /dev/ttyACM0 < /dev/ttyACM0


cat /dev/ttyACM0 &

echo 'AT+CSQ' > /dev/ttyACM0

killall cat


signal-strength, error-rate

In my case bit error rate is not supported (99) by the modem.

Signal strength

<9    Marginal
10~14 OK
15~19 Goold
>20   Excellent


AT Command


AT                Attention

returns OK which implies that the communication between the device and the application has been verified.

AT+CSQ       Signal quality

AT+CGMI     Request manufacturer identification

AT+CGMM     Request model identification

AT+CGMR     Request revision identification

AT+CGSN     Request product serial number identification


echo 'AT+CGMM' > /dev/ttyACM0