We can even adjust the model to consider only the range of dBm values that we expect to see in practice. To see signal strengths as high as -20 dBm you must be located right next to the AP, but on the other hand, how weak of a signal can be “heard” by the receiver will depend on the receiver’s sensitivity and noise floor (the background noise).Īt this point, it seems natural to perform a simple one-to-one conversion to express dBm values as percentage, for example: 0 dBm = 100%, -1 dBm = 99%, -2 dBm = 98%, …, -98 dBm = 2%, -99 dBm = 1%, no signal = 0%.
Also, in practice, typical dBm measurements range approximately from -20 to -95 dBm. By now you can conclude that the closer the dBm value is to 0, the stronger the signal is. In the context of 802.11 networks, a signal received at -40 dBm (0.0001 mW) would be considered a very strong signal, while a signal received at -80 dBm (0.00000001 mW) would be considered very weak. In an inverse manner, to convert dDm to milliwatts values you would use: You can convert milliwatts values to dBm using the formula: It makes it possible to express both very large and very small values in a short form: dBm is a unit of comparison and we use it to compare a signal to 1 milliwatt of power. In fact, this is the reason we use dBm instead. Unfortunately, it is not how it works.īecause of physics and Isaac Newton’s Inverse-Square Law, signals attenuate very rapidly within just a few meters away from the transmitter and they will always measure below 1 mW at the receiver, making it impractical to use percentage values this way. So, if the AP is transmitting at 100 mW for example, 90% would mean the transmitted signal is being received at 90 mW, 80% at 80 mW, and so on. It should also help clarify why percentage values in WiFi Explorer might look so different when we compare them to the values we see in other tools.īefore we start discussing how the conversion works, let’s ask ourselves the following question: when we say that a network has 75% signal strength, what does that mean? Let’s assume for a moment that such value represents the percentage of transmitted power at which the signal is being received. The purpose of this blog is to describe this conversion process in WiFi Explorer. WiFi Explorer, as well as other wireless scanning tools, provides an option to display signal strength in dBm or percentage values.
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