AT+CSQ always returns bit error rate of 99 on MTSMC-C2-GP?

[Alan Wells]

I’m trying to use the AT+CSQ command documented here to return RSSI and bit error rate from the MTSMC-C2-GP for use in gauging signal quality. The response from the modem yields an RSSI measurement that is valid and varies as expected with the strength of the signal, but the bit error rate field always returns 99 (unknown or not detectable), for example:

+CSQ: 29,99

Is there something else I need to do in order to measure bit error rate?

[Darrik Spaude]

The following was already posted in our Support Portal, but I will add it here in case others have the same question:

For the CDMA (our C2) radio, the second parameter in +CSQ is the frame error rate () as a percentage. For AT+CSQ, if the is 99, then assume no errors detected as long as there is a signal strength reported. If +CSQ is 99,99, then the =99 means the frame error rate is truly unknown.

The command #CAI? also includes the along with , but in this command’s response is an integer rather than a percentage.

Example #1 (third number from right in #CAI? response is integer value and corresponds to second value in +CSQ response — here integer=0 and percentage=99 (undetectable)):
at#cai?
#CAI: 299,102,2441,4,384,256,6,6,6,-97,-12,0,2,0,0,0,2,0,0,0

OK
at+csq
+CSQ: 4,99

OK

Example #2 (third number from right in #CAI? response is integer value and corresponds to second value in +CSQ response — here integer=513 and percentage=6 — integer=416 and percentage=6):
at+csq
+CSQ: 5,6

OK
at#cai?
#CAI: 299,102,2713,4,384,88,6,6,6,-98,-10,-13,4,1,1,3,2,513,0,0

OK
at+csq
+CSQ: 6,6

OK
at#cai?
#CAI: 299,102,2713,4,384,88,6,6,6,-97,-7,-11,4,1,1,3,2,416,0,0

OK

The C2 AT command guide is here and includes +CSQ and #CAI:
–> http://www.multitech.com/manuals/s000546.pdf

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