Android 手机信号 dBm, asu

<3G与2G信号区分>

<BatteryStatsImpl.java>

if (!signalStrength.isGsm()) {

   int dBm = signalStrength.getCdmaDbm();
   if (dBm >= -75) bin = SIGNAL_STRENGTH_GREAT;
   else if (dBm >= -85) bin = SIGNAL_STRENGTH_GOOD;
   else if (dBm >= -95) bin = SIGNAL_STRENGTH_MODERATE;
   else if (dBm >= -100) bin = SIGNAL_STRENGTH_POOR;
   else bin = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
} else {
   int asu = signalStrength.getGsmSignalStrength();
   if (asu < 0 || asu >= 99) bin = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
   else if (asu >= 16) bin = SIGNAL_STRENGTH_GREAT;
   else if (asu >= 8) bin = SIGNAL_STRENGTH_GOOD;
   else if (asu >= 4) bin = SIGNAL_STRENGTH_MODERATE;
   else bin = SIGNAL_STRENGTH_POOR;

}

<Phone.java>

GSM信号单位<dBm-asu>换算公式:dBm = -113 -2*asu;

/**
* Get current signal strength. No change notification available on this
* interface. Use <code>PhoneStateNotifier</code> or an equivalent.
* An ASU is 0-31 or -1 if unknown (for GSM, dBm = -113 - 2 * asu).
* The following special values are defined:</p>
* <ul><li>0 means "-113 dBm or less".</li>
* <li>31 means "-51 dBm or greater".</li></ul>
*
* @return Current signal strength as SignalStrength
*/
SignalStrength getSignalStrength();