Beijer Electronics (formerly QSI Corporation)

Manufacturer of Mobile Data and Human Machine Interface Terminals.
It is currently Sun Nov 19, 2017 3:29 am

All times are UTC - 7 hours




Post new topic Reply to topic  [ 1 post ] 
Author Message
PostPosted: Mon May 16, 2011 10:01 am 
Offline
User avatar

Joined: Thu Jan 14, 2010 10:20 am
Posts: 38
The following are common steps to perform for troubleshooting a modem connection. The commands listed here are typically sent to the modem device via the program "\HardDisk\bin\mintermce.exe".

AT+CPIN?\r
Check the status of the SIM card:
SIM card successfully detected: +CPIN: READY
SIM card absent: ERROR
SIM card absent: +CME ERROR: 10
SIM card failure: +CME ERROR: 13

AT+CREG?\r
Check whether the modem has "found" the cellular towers and registered with them:
Not trying to register (SIM card bad/missing?): +CREG: 0,0
Registered with towers: +CREG: 0,1
Not yet registered with towers: +CREG: 0,2

AT+CSQ\r
+CSQ: <rssi>,<ber>

<rssi> (Signal Strength)
Parameter Description
0 -113 dBm or less
1 -111 dBm
2..30 -109... -53 dBm
31 -51 dBm or greater
99 not known or not detectable

<ber> (Bit Error Rate)
0..7 as RXQUAL values in the table in GSM 05.08 section 8.2.4.
http://www.etsi.org/deliver/etsi_gts/05/0508/05.01.00_60/gsmts_0508v050100p.pdf
99 not known or not detectable

Ballpark estimates (without considering <ber>):
1 Bars ~ -102 to -113 dBM ~ (rssi 0-5)
2 Bars ~ -93 to -101 dBM ~ (rssi 6-10)
3 Bars ~ -87 to -92 dBM ~ (rssi 11-13)
4 Bars ~ -78 to -86 dBM ~ (rssi 14-17)
5 Bars ~ -40 to -77 dBM ~ (rssi 18-30)

Notes:

The CSQ command is useless until you are first registered to the network. (just like a cell phone won't show you any "bars" until it's found the cell towers). Bit error rate may be affected by transmission channel noise, interference, distortion, attenuation, wireless multipath fading, etc. Typically the bit error improves (decreases) when the signal strength increases.

I've not yet found a command that allows one to discover whether a SIM card has been "activated" on a cellular network. An activated SIM card that is out of range of cellular towers may return +CREG 0,2 however an unactivated SIM card will ALWAYS return +CREG 0,2.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1 post ] 

All times are UTC - 7 hours


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group