Bars are a very basic representation of a complex set of logarithmic measurements. I don't think it's all that simple. They're probably doing something like a 9

Bars are a very basic representation of a complex set of logarithmic measurements. I don't think it's all that simple. They're probably doing something like a 95th-percentile calculation on top of that. You don't want to change the bar signal meter for every normal fluctuation in RF. Otherwise the bar meter would constantly be moving up and down all the time. From an RF perspective it's also not as simple as just looking at the signal level. You can have great signal levels and poor SNR for example.