Report signal strength via AT+CIND

[Amit Mendapara]

Many 3G modem reports various network information via AT+CIND command including signal strength. Few devices only support AT+CIND, for example the Teracom (Linktop LW273) distributed by BSNL in India, only reports signal strength of UMTS network via AT+CIND command.

It will be great if ModemManager add support for CIND by default and fallback to CSQ if CIND is not supported. This is already the behaviour of OFONO.

The process could be like this:

1. on connect find the singal index by issuing AT+CIND=? command else set CIND not supported
2. on get_signal_quality issue AT+CIND? if CIND is supported else issue AT+CSQ
3. on get_signal_quality_done if CIND is supported then get the singal from the given signal index and normalize value

With LW273 modem, I have following result for the CIND command:

AT+CIND=?
+CIND: ("battchg",(0-5)),("signal",(0-5)),("batterywarning",(0-1)),("chargerconnected",(0-1)),("service",(0-1)),("sounder",(0-1)),("message",(0-1)),()

OK
AT+CIND?
+CIND: 0,3,1,0,1,0,0,0,0,0,0,0

OK

So here the signal strength reported is 3 which is in the range of min 0 to max 5. So the value should be normalized at follows:

quality = (signal * 100) / (5 - 0)

See http://bazaar.launchpad.net/~indicator-network-developers/ofono/trunk/annotate/head:/drivers/atmodem/network-registration.c#L773 for more information.

[Dan Williams (dcbw)]

Should work as of dc95f531adc38166cb4ec0ec08e40527dd04385a upstream, please test and let me know. If you test, please include full modem-manager --debug output so we can diagnose any problems. Also, it's best to track modem-manager problems upstream at bugzilla.gnome.org since I don't often look directly at launchpad, as LP is Ubuntu-specific.

[Amit Mendapara (cristatus)]

Thanks Dan for the quick changes. However, it's not working. I have reported the bug upstream (https://bugzilla.gnome.org/show_bug.cgi?id=636040) and will provide debug info there.

[Amit Mendapara (cristatus)]

The fix has been committed upstream.