信号强度中负数dbm的含义是什么？ [英] What is meaning of negative dbm in signal strength?

问题描述

当我们试图让邻近的单元格和他们的LAC，MNC发出信号（并且在使用其他android应用程序时），我们将信号看作负值（如-85dbm）。我应该如何接受这个？我应该忽略-ve签名和绝对值，或-85比-60强度小吗？

这将如何影响我的定位？

解决方案

以dBm为单位的功率是实际功率/ 1毫瓦的比率的对数的10倍。

dBm代表分贝毫瓦。这是衡量权力的一种便捷方式。确切的公式是

 
 P（dBm）= 10·log10（P（W）/ 1mW）
  
 $ b其中
 $ b $ pre 
 P（dBm）=以dBm为单位的功率
 P（W）=以瓦特为单位的绝对功率
 mW = milliWatts 
 log10 =登录到基地10 
 

根据此公式，1瓦的dBm功率为30 dBm。因为计算是对数的，每增加3dBm大约相当于信号实际功率的两倍。

有一个转换计算器和一个比较表here 。
维基百科英文页面上也有对照表，但它给移动网络带来的价值有点小。你实际的问题是 - $符号计数？

答案是肯定的，它的确如此。
$ b -85 dBm不那么强大（小于）-60 dBm。要理解这一点，您需要查看负数。或者，考虑一下你的银行账户。如果你欠银行85美元/次/欧元/卢比（-85），那么你就比如果你只欠65（-65）那么贫穷，即-85小于-65。此外，在温度测量中，-85比-65度更冷。

移动网络的信号强度总是负的dBm值，因为传输的网络不够强给出正的dBm值。

这将如何影响您的位置查找？我不知道，因为我不知道你用什么技术来估计位置。您引用的值大致对应于GSM，UMTS或LTE中的5 bar网络，因此您不应因网络强度而出现任何问题。

When we try to get nearby cells and their LAC, MNC, signal (and while using other android apps) we are getting signal as negative value (like -85dbm). How should I take this? Should I ignore -ve sign and take absolute value or -85 is smaller strength than -60?

How this will affect my location finding?

解决方案

The power in dBm is the 10 times the logarithm of the ratio of actual Power/1 milliWatt.

dBm stands for "decibel milliwatts". It is a convenient way to measure power. The exact formula is

P(dBm) = 10 · log10( P(W) / 1mW ) 

where

P(dBm) = Power expressed in dBm   
P(W) = the absolute power measured in Watts   
mW = milliWatts   
log10 = log to base 10

From this formula, the power in dBm of 1 Watt is 30 dBm. Because the calculation is logarithmic, every increase of 3dBm is approximately equivalent to doubling the actual power of a signal.

There is a conversion calculator and a comparison table here. There is also a comparison table on the Wikipedia english page, but the value it gives for mobile networks is a bit off.

Your actual question was "does the - sign count?"

The answer is yes, it does.

-85 dBm is less powerful (smaller) than -60 dBm. To understand this, you need to look at negative numbers. Alternatively, think about your bank account. If you owe the bank 85 dollars/rands/euros/rupees (-85), you're poorer than if you only owe them 65 (-65), i.e. -85 is smaller than -65. Also, in temperature measurements, -85 is colder than -65 degrees.

Signal strengths for mobile networks are always negative dBm values, because the transmitted network is not strong enough to give positive dBm values.

How will this affect your location finding? I have no idea, because I don't know what technology you are using to estimate the location. The values you quoted correspond roughly to a 5 bar network in GSM, UMTS or LTE, so you shouldn't have be having any problems due to network strength.

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