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No signal problem with GSM modem

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simonleung

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Hi all,

I have a setup with wavecom Q64 + antenna and can't seem to get registered on a network.

There a two things that I think might be wrong:

1. signal: AT+CSQ always returns 99,99, with or without SIM. I read somewhere that this command can be issued in either situation, true?

2. IMEI: the IMEI of the module is 012345678901234 which looks invalid. Could it be that the network sees it as invalid and refuse to register it? Don't know.

Thanks for any input.
 

check the following things

1. do you use a valid SIM for the modem.
2. Is your SIM password protected, if yes disable that
3. Test Basic AT command and then try AT+CPIN=................
see if sim is detected.
4. check if the antenna port is connected to antenna pad on the board.
5. Do an AT&F and try again
 

Thanks.

I've tried a few combinations:
SIM + antenna
SIM + no antenna
No SIM + antenna
No SIM + no antenna

And in all situations, CSQ command always returns 99,99.

AT commands are fine, I can unlock the SIM card with a PIN (I'm using the module with SIM from my phone).

---------- Post added at 11:09 ---------- Previous post was at 11:08 ----------

Also, what does AT&F do?
 

AT&F resets modem to factory settings. You loose configuration data stored in modem's flash. may be your antenna is not good. can you solder a long wire of about 15cms and turn 5 coils and make it as spiral / loop antenna and solder the wire to antenna pad. (dimension of wire or loop not a problem).
I suspect problem with antenna, Replace the antenna or make a antenna from wire and test it. it should definetely work if the modem is not faulty.
 
I've used a multimeter to check the antenna and it appears to be OK. Is it still a good idea to try preparing my own antenna? Otherwise I'll just RMA it.
 

Definetely yes, as i usually make antenna for my modems just to save the cost of antenna, few times i got faulty antenna with module, so when nothing works there is no harm in trying something which is a ray of hope. definetely it will not harn the module.

With multimeter you cannot find out as there will be a small coil at the antenna or it has very low impedance, multimeter will show short in any case. you remove or keep antenna, it shows low or zero resistance, you cannot check it with multimeter
 

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