why is signal strength displayed as negative decibels, for example “- 50 dB”?

Question

I see such measurement everywhere – cellphone antenass, router strength, etc. Shouldn’t signal strength be displayed as a positive number?

In: Technology

Answer 1

* Decibels are a relative measurement.
* They need some sort of reference.
* When you are talking about broadcast signals, you use the full strength broadcast level as the reference.
* Naturally any broadcast signal will lose some strength on its way to the receiver.
* So when we measure that level at the receiver, it will naturally be less than the full-strength reference, so the measurement is negative.