[android-SignalStrength]

一.根据3GPP TS 27.007 8.5 协议规定也就是ASU 是底层直接返回协议数据规定如下

 

{

rssi:interger type

0-113 dBm or less

1-111 dBm

2-30-53dBm

31-51dBm or greater

99not know or not detectable

}

 

二.SignalStrength 通过如上RSSI 也就是ASU 来判断级别

 

public int getGsmLevel() {

 

 

int level;

 

/ ASU ranges from 0 to 31 - TS 27.007 Sec 8.5

/ asu = 0 (-113dB or less) is very weak

/ signal, its better to show 0 bars to the user in such cases.

/ asu = 99 is a special case, where the signal strength is unknown. int asu = getGsmSignalStrength();

/*

 

dBm与 RSSI转换公式:dBm=-113 + (2 * asu); */

if (asu <= 2 || asu == 99) level = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;<=-109dBm,==85dBm

else if (asu >= 12) level = SIGNAL_STRENGTH_GREAT;>=-89dBm

else if (asu >= 8) level = SIGNAL_STRENGTH_GOOD;>-97dBm

else if (asu >= 5) level = SIGNAL_STRENGTH_MODERATE;>=-103dBm

else level = SIGNAL_STRENGTH_POOR; if (DBG) log("getGsmLevel=" + level); return level;

 

}

 

 

三.SignalStrength 通过如下接口供上层根据 ASU 转换成dBm

 

 

/**

* Return current signal strength in "dBm", ranging from -113 - -51dBm

* or -1 if unknown

*

* @return signal strength in dBm, -1 if not yet updated

* Throws RuntimeException if client has not called notifySignalStrength()

*/

public int getSignalStrengthDbm() {

if ((mWants & NOTIF_SIGNAL) == 0) { throw new RuntimeException

("client must call notifySignalStrength(int)");

}

return mSignalStrength.getDbm();

}

 

public int getGsmDbm() { int dBm;

 

int gsmSignalStrength = getGsmSignalStrength();

int asu = (gsmSignalStrength == 99 ? -1 : gsmSignalStrength); if (asu != -1) {

dBm = -113 + (2 * asu);

} else { dBm = -1;

 

}

if (DBG) log("getGsmDbm=" + dBm); return dBm;

}