The signal strength for one of my installation is appr. 9 when normal interval is between 1-32 (datasheet).
Is it possible that if the signal strength is too low, the module is not able to connect and transmit data through gprs sockets?
My application transmits data packages to a server, periodically. Each data pacakage includes the signal strength value, among other things. The last package received showed signal strength == 24.
This is equal to good signal strength.
I haven’t received packages for 2 days now, but the module is answering to my status information request via SMS message. The status information includes the signal strength and showes strength == 9.
Every 24 hours I force reset of the application/module, and furthermore I use at+cfun=0 followed by at+cfun=1 to make it re-connect to a valid network cell.
Could it be that the module has found a new cell to connect to, which leads to lower signal strength, and therefore is not returning data pacakages?
It’s exactly the same as using a mobile phone - when the signal’s poor, the connection is unreliable.
This is an inherent feature of all radio-based communications, so your application must be carefully designed to cope with it.
You must also set appropriate expectations to accept that, when the signal’s really bad, communication is simply not possible.
Yes, that’s quite poor - see:
The module should automatically use the cell with the best available signal.
It may not be (just) an issue of the "raw"strength - there could also be other network issue, or interference, etc, etc…
Also, a single signal strength reading of 9 is next to meaningless - it might have been a “lucky” peak, when the usual value is only 2…
Maybe there’s just brief periods of 9, but most of the time there’s nothing at all - so it depends on whether your application happens to be “lucky” that it tried to transmit when there happened to be service available…
etc, etc,…
That is correct.
It is still strange how the signal strength for my network connection can drop from 24 to 9. The module/application had been running for several months without drop outs. Maybe it is the antenna loosing gain, or local interference blocking…