Android信号强度计算方式

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;

     }