Wiki source code of Signal Strength:99. CSQ:99,99
Version 10.1 by Edwin Chen on 2023/04/23 23:29
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| author | version | line-number | content |
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| 1 | |||
| 2 | |||
| 3 | **Table of Contents:** | ||
| 4 | |||
| 5 | {{toc/}} | ||
| 6 | |||
| 7 | |||
| 8 | = 1. Issue Output = | ||
| 9 | |||
| 10 | ---- | ||
| 11 | |||
| 12 | NB-IoT module can't connect to NB-IoT Network and Keep Showing Signal Strenght:99. Below is an example output: | ||
| 13 | |||
| 14 | [[image:image-20230423223628-1.png]] | ||
| 15 | |||
| 16 | |||
| 17 | = 2. What is Signal Strenght? = | ||
| 18 | |||
| 19 | Signal Strength is same as AT+CSQ command output. When you run **AT+CSQ** and NB-IoT module return **AT+CSQ=99,99**. It means NB-IoT Sensor doesn't attached to the NB-IoT network. If attached to network, the first 99 should be 2~~31. | ||
| 20 | |||
| 21 | ((( | ||
| 22 | Below is the definition for the (% style="color:blue" %)**AT+CSQ** | ||
| 23 | ))) | ||
| 24 | |||
| 25 | [[image:image-20220530094441-1.png]] | ||
| 26 | |||
| 27 | CSQ Definition | ||
| 28 | |||
| 29 | |||
| 30 | = 3. What to check? = | ||
| 31 | |||
| 32 | == 3.1 Check whether module detect the SIM card? == | ||
| 33 | |||
| 34 | You can see if the output shows the **IMSI number**. If NB-IoT module detects SIM card successful, There will be a IMSI number shown, this is from the SIM card. If SIM card not detect, please check: | ||
| 35 | |||
| 36 | * If SIM card is placed in correct direction. | ||
| 37 | * Make sure there is power off / power on after insert SIM card. | ||
| 38 | |||
| 39 | == 3.2 Whether you use a NB-IoT SIM card that the module supports == | ||
| 40 | |||
| 41 | * Make sure the SIM card you use is a **NB-IoT SIM card**. It is different from normal SIM card we use for mobile. | ||
| 42 | * If you use a NB-IoT SIM card, check whether the **Frequency Band** of this operator are in the support list of the NB-IoT Sensor. | ||
| 43 | |||
| 44 | == 3.3 Whether the antenna connection is good == | ||
| 45 | |||
| 46 | See the connection of Antenna Path is loose. | ||
| 47 | |||
| 48 | [[image:image-20230423230549-2.png||height="370" width="428"]] | ||
| 49 | |||
| 50 | |||
| 51 | == 3.4 Check Software Settings == | ||
| 52 | |||
| 53 | In the NB-IoT Sensor which power by battery. The sensor will try to connect to NB-IoT in a specify time (For example 5 minutes), if sensor is not able to attach network in 5 minutes. Sensor will stop retry and put the NB-IoT module in sleep mode to save battery life. So in the case that attaching network needs more time than 5 minutes, it will cause module hard to attach NB-IoT network. There are two solution to solve this. | ||
| 54 | |||
| 55 | === 3.4.1 Extend attach time === | ||
| 56 | |||
| 57 | User can use AT Command to extend network acquisition time.For example **AT+CSQTIME=10** will extend the network acquisition time to 10 minutes. | ||
| 58 | |||
| 59 | |||
| 60 | === 3.4.2 Lock Frequency Band === | ||
| 61 | |||
| 62 | NB-IoT module by default support multi-bands, and it will try to use these bands to attached network one by one. User can lock the frequency band to the SIM card band to speed up the process. | ||
| 63 | |||
| 64 | See [[how to lock frequency band>>doc:Main.Specify NB-IoT Band.WebHome]]. | ||
| 65 | |||
| 66 |