What is a strong signal? Analysis of signal units of dbm and asu | Ainongji - 上海419贵族宝贝-上海后花园1314-上海品茶网-阿拉爱上海

In the past, we used to judge the signal strength of a mobile phone by the number of signal cells on the phone, but it is worth noting that in fact, there is no unified standard for the conversion relationship between the signal strength and cell number of a mobile phone. For example, Nokia's 4-cell signal may not be worse than the iPhone's 5-cell signal. How to judge the strength of the signal? stay Wang Ziyou's nearest MX2 evaluation A very important part of the content is the comparative test of mobile phone signal strength. Let's have a deep understanding of mobile phone signal!

In Android phone settings, we can see the status information about signal strength, which can see an item about signal strength, in dBm and asu. Where dBm (decibels of 1 milliwatt) It is a general indicator to measure the signal strength of mobile phones. If you dial * 3001 # 12345 # * with iPhone, you can enter the engineering mode. The number in the upper left corner is the signal strength, and asu (one signal unit) is G The unique signal unit defined by oogle for Android phones The relationship between them is: dBm=- 113+2 * asu.

DBm is a value representing the absolute value of power (also can be considered as a ratio based on 1mW power),
The calculation formula is: 10log (power value/1mw).

[Example] If the power P is 1mw, it will be 0dBm after being converted to dBm.
[Example] For 0.01mW power, the value after conversion in dBm units should be: 10log (0.01/1)=- 20dBm.

The higher the value, the better the signal. Due to the low signal strength of mobile phones, dBm is generally a negative number, as shown in the following figure:

The signal strength of the screenshot is - 97 dbm, and the signal strength of 8 asu is barely passed. Because when the dbm is lower than - 113, there is no signal. Generally, the asu can see 10-30, which is a relatively normal category. The larger the asu value, the better the signal strength. If you find that your ASU is greater than 35, you should be near the BTS. If the ASU is less than 10, the signal is poor. So when dbm>=- 90, asu>=10, the signal is normal.

Relation between signal strength and signal grid number display: engineers divide the signal grid number according to the acceptance level value. The more complex data is intuitively expressed in the signal lattice number before our eyes.

Comparison of signal strength and number of cells between Nokia mobile phone and iPhone 4

It can be seen from the above table that, assuming that at the same reception level, when the Nokia mobile phone displays four bars of signals, the iPhone 4 or five bars will still have two bars of signals when Nokia is offline. Regardless of the number of bars displayed, the requirements for the mobile phone reception sensitivity dBm value in the GSM protocol are the same. Of course, there are small differences between different manufacturers in the division of signal cells for level values, and there will also be individual differences and differences in level acceptance between mobile phones. Every country and even every operator has different standards. According to the specifications of China Mobile, when the mobile phone reception level is>=(- 90dBm for cities and - 94dBm for villages), the coverage requirements are met. That is to say, the wireless signal strength here meets the coverage requirements, that is, when the reception level is>=- 90dBm, the coverage requirements can be met, You can also use this value to measure whether your signal is up to standard.