GSM LTE信号强度

GSM: dBm = -113 -2*asu

LTE：dBm = -140 + asu

frameworks/base/telephony/java/android/telephony/SignalStrength.java

    public int getLevel() {
        int level;

        if (isGsm) {
            level = getLteLevel();
            //MTE-START [ALPS01200757]
            //if (level == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) {
            if (!isCampOnLte()) {
            //MTE-END [ALPS01200757]
                level = getGsmLevel();
            }
        } else {
            int cdmaLevel = getCdmaLevel();
            int evdoLevel = getEvdoLevel();
            if (evdoLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) {
                /* We don't know evdo, use cdma */
                level = cdmaLevel;
            } else if (cdmaLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) {
                /* We don't know cdma, use evdo */
                level = evdoLevel;
            } else {
                /* We know both, use the lowest level */
                level = cdmaLevel < evdoLevel ? cdmaLevel : evdoLevel;
            }
        }
        if (DBG) {
            log("getLevel=" + level);
        }
        return level;
    }