ILD

RSSI和dbm
作者:Yuan Jianpeng 邮箱:yuanjianpeng@xiaomi.com
发布时间:2021-5-8 站点:Inside Linux Development

RSSI (Received signal strength indication)

RSSI用来评估信号的相对强度,IEEE 802.11标准规定RSSI取值范围是0-255,值越大信号越强。每个芯片厂商可以定义自己的RSSI最大值,比如CISCO的最大值是100,其RSSI取值范围是0-100。

OpenWrt计算Signal时,将其值减去255。


dbm

贝是衡量一个数和标准数之间的关系:lg(a/b)。对于功率,分贝是1/10贝。对于振幅(位移,速度,加速度,声压),分贝是1/20贝。声音的分贝是声压和2*10^-5pa的比值。通常3分贝是2倍的比值。dbm是功率,m表示milliwatts毫瓦。功率和毫瓦的比值。


对于无线接收信号强度:

Signal StrengthTL;DR Required for
-30 dBmAmazingMax achievable signal strength. The client can only be a few feet from the AP to achieve this. Not typical or desirable in the real world.N/A
-67 dBmVery GoodMinimum signal strength for applications that require very reliable, timely delivery of data packets.VoIP/VoWiFi, streaming video
-70 dBmOkayMinimum signal strength for reliable packet delivery.Email, web
-80 dBmNot GoodMinimum signal strength for basic connectivity. Packet delivery may be unreliable.N/A
-90 dBmUnusableApproaching or drowning in the noise floor. Any functionality is highly unlikely.N/A



https://en.wikipedia.org/wiki/DBm

https://en.wikipedia.org/wiki/Received_signal_strength_indication

https://www.metageek.com/training/resources/understanding-rssi.html

https://zhuanlan.zhihu.com/p/22821588


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