GSM的计算方式：
A: 这个是GSM的，LTE的是否应该有所不同。
ASU转换成dBm：dBm=-113+（2*ASU）
All
* Get the GSM Signal Strength, valid values are (0-31, 99) as defined in TS
* 27.007 8.5
if (asu <= 2 || asu == 99) level = SIGNAL_STRENGTH_NONE_OR_UNKNOWN(0);
else if (asu >= 12) level = SIGNAL_STRENGTH_GREAT(4);
else if (asu >= 8) level = SIGNAL_STRENGTH_GOOD(3);
else if (asu >= 5) level = SIGNAL_STRENGTH_MODERATE(2);
else level = SIGNAL_STRENGTH_POOR(1);
LTE：
LTE的计算方式好像与信噪比和信号接收质量有关系，详情如下，（SignalStrength.java）
还有CDMA 的也在这个文件中。
/*
* TS 36.214 Physical Layer Section 5.1.3 TS 36.331 RRC RSSI = received
* signal + noise RSRP = reference signal dBm RSRQ = quality of signal
* dB= Number of Resource blocksxRSRP/RSSI SNR = gain=signal/noise ratio
* = -10log P1/P2 dB
*/
int rssiIconLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN, rsrpIconLevel = -1, snrIconLevel = -1;
if (mLteRsrp > -44) rsrpIconLevel = -1;
else if (mLteRsrp >= -85) rsrpIconLevel = SIGNAL_STRENGTH_GREAT;
else if (mLteRsrp >= -95) rsrpIconLevel = SIGNAL_STRENGTH_GOOD;
else if (mLteRsrp >= -105) rsrpIconLevel = SIGNAL_STRENGTH_MODERATE;
else if (mLteRsrp >= -115) rsrpIconLevel = SIGNAL_STRENGTH_POOR;
else if (mLteRsrp >= -140) rsrpIconLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
/*
* Values are -200 dB to +300 (SNR*10dB) RS_SNR >= 13.0 dB =>4 bars 4.5
* dB <= RS_SNR < 13.0 dB => 3 bars 1.0 dB <= RS_SNR < 4.5 dB => 2 bars
* -3.0 dB <= RS_SNR < 1.0 dB 1 bar RS_SNR < -3.0 dB/No Service Antenna
* Icon Only
*/
if (mLteRssnr > 300) snrIconLevel = -1;
else if (mLteRssnr >= 130) snrIconLevel = SIGNAL_STRENGTH_GREAT;
else if (mLteRssnr >= 45) snrIconLevel = SIGNAL_STRENGTH_GOOD;
else if (mLteRssnr >= 10) snrIconLevel = SIGNAL_STRENGTH_MODERATE;
else if (mLteRssnr >= -30) snrIconLevel = SIGNAL_STRENGTH_POOR;
else if (mLteRssnr >= -200)
snrIconLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
if (DBG) log("getLTELevel - rsrp:" + mLteRsrp + " snr:" + mLteRssnr + " rsrpIconLevel:"
+ rsrpIconLevel + " snrIconLevel:" + snrIconLevel);
/* Choose a measurement type to use for notification */
if (snrIconLevel != -1 && rsrpIconLevel != -1) {
/*
* The number of bars displayed shall be the smaller of the bars
* associated with LTE RSRP and the bars associated with the LTE
* RS_SNR
*/
return (rsrpIconLevel < snrIconLevel ? rsrpIconLevel : snrIconLevel);
}
if (snrIconLevel != -1) return snrIconLevel;
if (rsrpIconLevel != -1) return rsrpIconLevel;
/* Valid values are (0-63, 99) as defined in TS 36.331 */
if (mLteSignalStrength > 63) rssiIconLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
else if (mLteSignalStrength >= 12) rssiIconLevel = SIGNAL_STRENGTH_GREAT;
else if (mLteSignalStrength >= 8) rssiIconLevel = SIGNAL_STRENGTH_GOOD;
else if (mLteSignalStrength >= 5) rssiIconLevel = SIGNAL_STRENGTH_MODERATE;
else if (mLteSignalStrength >= 0) rssiIconLevel = SIGNAL_STRENGTH_POOR;
if (DBG) log("getLTELevel - rssi:" + mLteSignalStrength + " rssiIconLevel:"
+ rssiIconLevel);
return rssiIconLevel;
TD-SCDMA的计算方式：
framework/base/SignalStrength.java
public int getTdScdmaLevel() {
final int tdScdmaDbm = getTdScdmaDbm();
int level;
if ((tdScdmaDbm > -25) || (tdScdmaDbm == SignalStrength.INVALID))
level = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
else if (tdScdmaDbm >= -49) level = SIGNAL_STRENGTH_GREAT;
else if (tdScdmaDbm >= -73) level = SIGNAL_STRENGTH_GOOD;
else if (tdScdmaDbm >= -97) level = SIGNAL_STRENGTH_MODERATE;
else if (tdScdmaDbm >= -120) level = SIGNAL_STRENGTH_POOR;
else level = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
if (DBG) log("getTdScdmaLevel = " + level);
return level;
}
原文地址：http://8202061.blog.51cto.com/8192061/1621416
