User guide

EG_GenPro2xe_1003_UG_005_UK Page 28 / 63
Descriptions and non-contractual illustrations in this document are given as an indication only.
ERCO&GENER reserves the right to make any modifications.
Dct_427_00
5.5 Checking the quality of the GSM reception signal
The modem contains the EGM standard library (see the documents "EG_EGM_CL_xxx_yy" of ERCO &
GENER) in this case, the modem will be able to make a call only if the received GSM signal is sufficient.
The command AT+CSQ allows to know the reception level (rssi) of the signal sent by the closest GSM Base
Transceiver Station (BTS), as well as the receive bit error rate (ber).
When the SIM card is inserted and the PIN code entered, the command AT+CSQ allows to measure the
signal from the BTS of the subscribed operator network.
This command can also be used without the SIM card, it indicates in this case the nearest BTS which can be
ORANGE, SFR or BOUYGUES for France (Without SIM card, the current subscription is not recognized).It is
therefore advisable to do the measure when the SIM card is present.
To check the quality of the GSM signal, do the following operations:
Use a communication software like Hyperterminal, enter the command AT+CSQ.
The response is in the following format:
+CSQ : <rssi>, <ber> with:
<rssi> = indicates the reception level,
<ber> = receive bit error rate.
Check the returned value <rssi> with the help of the table below.
<rssi> Value Gain in dbm Interpretation <ber> Value Interpretation
0 -113 dbm Insufficient 0 à 7
See ETSI GSM 05.08
standards
1 à 10 -111 à -95 dbm Insufficient
11 à 30 -93 à -53 dbm Insufficient
31 (max) -51dbm Perfect
99 Unknown/not detectable 99 Unknown/not detectable
The GSM modem works normally with a minimum <rssi> between 11 and 15.
Bellow 10, the signal level is insufficient; the modem cannot work depending on the geographical situation or
the vehicle mobility. Above 15, the signal is sufficient.
For more information about AT commands, see the document "EG_EGM_CL_xxx_yy" of ERCO & GENER.