How to check 3G modem RSSI Signal Quality
I used minicom and set it to 9600 baud rate and also must set the serial device to tty/USB on which your USB detected. Below is the details. ===================== Signal quality Command: AT+CSQ Response: +CSQ: , Description: Returns signal quality. Received Signal Strength Indicator 0 -113 dBm or less 1 -111 dBm 2 to 30 -109 to -53 dBm 31 -51 dBm or greater 99 not known or not detectable Bit Error Rate, in percent 0..7. 99 not known or not detectable A note on the RSSI (received signal strength), dBm is a decibel (logarithmic) scale with a reference of 1 milliwatt thus 0 dBm equals a received signal of 1 mW. Signal strength is usually lower than 1 mW and therefore below 0, so the larger (closer to 0) the better signal strength. You can convert the RSSI to dBM with dBm = (rssi \times 2) - 113 Example >AT+CSQ=? +CSQ: (0-31,99),(99) OK >AT+CSQ +CSQ: 14,99 Courtesy of Shapeshifter