AT+CESQ signal strength 255 (unknown) yet connection works great

[GJSea]

Hi,

In order to determine signal strength we parse the AT+CESQ response and regularly get +CESQ: 99,99,255,255,255,255 (the final number being the strength), but the connection and connectivity is perfectly fine. Is there a reason 255 is returned for the strength even though all connectivity is good?

Thanks! 

[Henry_Chou]

In my MQTT project.

@ CDMA echo={ AT+CREG?...+CREG: 2,1,"27E8","01965335",7....OK... }
@ CDMA echo={ AT+CESQ...+CESQ: 99,99,255,255,20,64....OK... }
@ CDMA echo={ AT+CSQ...+CSQ: 31,4....OK... }

AT+CESQ the final bytes is not 255. it shoulde be (0-97,255)

<rsrp> Number Reference Signal Received Power (RSRP):
• 0: less than -140 dBm
• 1..96: from -140 dBm to -45 dBm with 1 dBm steps
• 97: -44 dBm or greater
• 255: not known or not detectable

I am not sure why your URC return is 255?

Maybe it depends on the CDMA/4G system services side.