9月 152015
AT+CSQ语法
命令解释：检查网络信号强度
命令格式：AT+CSQ<CR>
命令返回：+CSQ: **, ## 其中：
- **应在 0 到 31 之间（99表示无信号），数值越大表明信号质量越好；
- ##为误码率，值在 0 到 99 之间。否则应检查天线或 SIM 卡是否正确安装
测试结果：AT+CSQ<CR>
计算公式：信号强度 = -113dBm + (rssi * 2)
通过AT+CSQ指令获取GPRS模块信号强度
如下图所示：
信号格数与信号强度的关系
手机格数与手机接收基站的信号强度有关，目前行业中并没有明确的标准，格数与信号强度关联均为厂商而定，iPhone 4信号强度与格数如下图：
诺基亚手机和iPhone 4信号强度与格数对比如下：
|
信号格数 |
接收电平强度 |
|
|
诺基亚 |
iPhone4 |
|
|
5格： |
大于-85dBm |
大于-91dBm |
|
4格: |
-85dBm至-90dBm |
-91dBm至-101dBm |
|
3格: |
-90dBm至-95dBm |
-101dBm至-103dBm |
|
2格: |
-95dBm至-100dBm |
-103dBm至-107dBm |
|
1格: |
-100dBm至-105dBm |
-107dBm至-113dBm |
|
脱网： |
小于-105 dBm |
小于-113dBm |
注：上表数据均为5格信号显示方式，如N97等7格信号原则与上述不同。
在这里，我采用了android系统上关于GSM模块信号格数与信号强度的对应关系，如下代码所示：
01 | public int getGsmLevel() { |
02 | int level; |
03 |
04 | // ASU ranges from 0 to 31 - TS 27.007 Sec 8.5 |
05 | // asu = 0 (-113dB or less) is very weak |
06 | // signal, its better to show 0 bars to the user in such cases. |
07 | // asu = 99 is a special case, where the signal strength is unknown. |
08 | int asu = getGsmSignalStrength(); |
09 |
10 | if (asu <= 2 || asu == 99) level = SIGNAL_STRENGTH_NONE_OR_UNKNOWN; |
11 | else if (asu >= 12) level = SIGNAL_STRENGTH_GREAT; |
12 | else if (asu >= 8) level = SIGNAL_STRENGTH_GOOD; |
13 | else if (asu >= 5) level = SIGNAL_STRENGTH_MODERATE; |
14 | else level = SIGNAL_STRENGTH_POOR; |
15 |
16 | if (DBG) log("getGsmLevel=" + level); |
17 |
18 | return level; |
19 | } |
上面的asu即AT+CSQ指令返回的RSSI值。
参考文章：http://blog.csdn.net/garybook/article/details/17006609
如果是CDMA模块，应该可以参考下面的代码：
参考文章：http://www.2cto.com/kf/201306/218756.html
在Android4.0的系统中，手机中显示信号强度格数的代码在
frameworks\base\telephony\java\android\telephony\SignalStrength.java
getLevel( )函数，该函数是主要用来获取信号的强度。
01 | public int getLevel() { |
02 | int level; |
03 | |
04 | if (isGsm) { |
05 | level = getLteLevel(); |
06 | if (level == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
07 | level = getGsmLevel(); |
08 | } |
09 | } else { |
10 | int cdmaLevel = getCdmaLevel(); |
11 | int evdoLevel = getEvdoLevel(); |
12 | if (evdoLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
13 | /* We don't know evdo, use cdma */ |
14 | level = cdmaLevel; |
15 | } else if (cdmaLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
16 | /* We don't know cdma, use evdo */ |
17 | level = evdoLevel; |
18 | } else { |
19 | /* We know both, use the lowest level */ |
20 | //level = cdmaLevel < evdoLevel ? cdmaLevel : evdoLevel; |
21 | level = cdmaLevel > evdoLevel ? cdmaLevel : evdoLevel; |
22 | } |
23 | } |
24 | if (DBG) log("getLevel=" + level); |
25 | return level; |
26 | } |
27 |
28 | public int getLevel() { |
29 | int level; |
30 |
31 | if (isGsm) { |
32 | level = getLteLevel(); |
33 | if (level == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
34 | level = getGsmLevel(); |
35 | } |
36 | } else { |
37 | int cdmaLevel = getCdmaLevel(); |
38 | int evdoLevel = getEvdoLevel(); |
39 | if (evdoLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
40 | /* We don't know evdo, use cdma */ |
41 | level = cdmaLevel; |
42 | } else if (cdmaLevel == SIGNAL_STRENGTH_NONE_OR_UNKNOWN) { |
43 | /* We don't know cdma, use evdo */ |
44 | level = evdoLevel; |
45 | } else { |
46 | /* We know both, use the lowest level */ |
47 | //level = cdmaLevel < evdoLevel ? cdmaLevel : evdoLevel; |
48 | level = cdmaLevel > evdoLevel ? cdmaLevel : evdoLevel; |
49 | } |
50 | } |
51 | if (DBG) log("getLevel=" + level); |
52 | return level; |
53 | } |
getCdmaLevel( )获取CdmaLevel，同样也有getEvdoLevel( )函数，在上一个函数中，通过比较Evdo和Cdma的强度，来最终确定信号的显示强度，也就是我们在通知栏里看到的信号格数。
01 | public int getCdmaLevel() { |
02 | final int cdmaDbm = getCdmaDbm(); |
03 | final int cdmaEcio = getCdmaEcio(); |
04 | int levelDbm; |
05 | int levelEcio; |
06 | |
07 | if (cdmaDbm >= -75) levelDbm = SIGNAL_STRENGTH_GREAT; |
08 | else if (cdmaDbm >= -85) levelDbm = SIGNAL_STRENGTH_GOOD; |
09 | else if (cdmaDbm >= -95) levelDbm = SIGNAL_STRENGTH_MODERATE; |
10 | else if (cdmaDbm >= -100) levelDbm = SIGNAL_STRENGTH_POOR; |
11 | else levelDbm = SIGNAL_STRENGTH_NONE_OR_UNKNOWN; |
12 | |
13 | // Ec/Io are in dB*10 |
14 | if (cdmaEcio >= -90) levelEcio = SIGNAL_STRENGTH_GREAT; |
15 | else if (cdmaEcio >= -110) levelEcio = SIGNAL_STRENGTH_GOOD; |
16 | else if (cdmaEcio >= -130) levelEcio = SIGNAL_STRENGTH_MODERATE; |
17 | else if (cdmaEcio >= -150) levelEcio = SIGNAL_STRENGTH_POOR; |
18 | else levelEcio = SIGNAL_STRENGTH_NONE_OR_UNKNOWN; |
19 | |
20 | int level = (levelDbm < levelEcio) ? levelDbm : levelEcio; |
21 | if (DBG) log("getCdmaLevel=" + level + ",cdmaDbm=" + cdmaDbm + ",cdmaEcio=" +cdmaEcio); |
22 | return level; |
23 | } |
24 |
25 | public int getCdmaLevel() { |
26 | final int cdmaDbm = getCdmaDbm(); |
27 | final int cdmaEcio = getCdmaEcio(); |
28 | int levelDbm; |
29 | int levelEcio; |
30 |
31 | if (cdmaDbm >= -75) levelDbm = SIGNAL_STRENGTH_GREAT; |
32 | else if (cdmaDbm >= -85) levelDbm = SIGNAL_STRENGTH_GOOD; |
33 | else if (cdmaDbm >= -95) levelDbm = SIGNAL_STRENGTH_MODERATE; |
34 | else if (cdmaDbm >= -100) levelDbm = SIGNAL_STRENGTH_POOR; |
35 | else levelDbm = SIGNAL_STRENGTH_NONE_OR_UNKNOWN; |
36 |
37 | // Ec/Io are in dB*10 |
38 | if (cdmaEcio >= -90) levelEcio = SIGNAL_STRENGTH_GREAT; |
39 | else if (cdmaEcio >= -110) levelEcio = SIGNAL_STRENGTH_GOOD; |
40 | else if (cdmaEcio >= -130) levelEcio = SIGNAL_STRENGTH_MODERATE; |
41 | else if (cdmaEcio >= -150) levelEcio = SIGNAL_STRENGTH_POOR; |
42 | else levelEcio = SIGNAL_STRENGTH_NONE_OR_UNKNOWN; |
43 |
44 | int level = (levelDbm < levelEcio) ? levelDbm : levelEcio; |
45 | if (DBG) log("getCdmaLevel=" + level + ",cdmaDbm=" + cdmaDbm + ",cdmaEcio=" +cdmaEcio); |
46 | return level; |
47 | } |
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