User guide

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Description and non-contractual illustrations in this document are given as an indication only.
ERCO & GENER reserves the right to make any modifications.
5.5 Verifying GSM receive signal quality
The modem will be able to establish a call only if the received GSM signal is of a sufficient level.
The command AT+CSQ will return the reception level (rssi) of the signal sent by the closest GSM Base
Transceiver Station (BTS), as well the receive bit error rate (ber).
When the SIM card is present and the PIN code has been entered, the command AT+CSQ will return the
signal level from the BTS on the subscribed operator network.
When used without the SIM card, this command will simply indicate the closest BTS due to the fact that the
modem cannot identify the current subscription. It is therefore advisable to make this test with the SIM card
present.
To verify the GSM signal quality, perform the following operations:
Using a communication application, enter the command AT+CSQ.
The response is in the following format:
+CSQ: <rssi>,<ber> where : <rssi> = indicates the reception level,
<ber> = receive bit error rate.
Verify the value <rssi> with the aid of the table below:
<rssi> value Gain (dbm) Interpretation <ber> value Interpretation
0 -113 dbm Insufficient 0 to 7
See standard ETSI
GSM 05.08
1 to 10 -111 to -95 dbm Insufficient
11 to 30 -93 to -53 dbm Sufficient
31 (max) -51dbm Perfect
99 Unknown/not detectable 99 Unknown/not detectable
The GSM modem will function correctly with a minimum <rssi> of between 11 and 15.
Below 10 the signal is insufficient, the modem cannot function depending on the geographical situation or the
mobility of the vehicle. Above 15 the signal is of a sufficient level.
For more information about the AT commands see the "Commands List" from ERCO & GENER.