Wireless Signal Strength - comparing -dBm to %?

[jrichrds]

My old wireless adapter reported 75% signal strength, but WinXP's Wireless Zero Config only gave it a "very good" (4 out of 5 bars) rating.

My new wireless adapter (Intel 2200BG Centrino) reports -50dBm signal strength, but wireless zero config gives it an "excellent" (5 out of 5 bars) rating.

So I'm confused...doesn't -50dBm = 50% signal strength? How does that end up beating out the 75% signal strength of my old wireless adapter?

 

[Fardringle]

There are two very important items to consider when measuring a wireless (radio) signal.

They are signal strength and signal quality.

Signal strength is simply a measure of how strong the radio signal is (measured in dBM). Signal strength is primarily an indicator of how far the signal can be broadcast.

Signal quality is a measure of the signal to noise ratio. It is possible to have an extremely weak (low dBM) signal that is still an Excellent quality signal if its signal to noise ratio is high enough. Static on a radio station in your car is a good example of low signal to noise ratio. Signal quality is an indicator of how usable the contents of the signal are.

From your description, it sounds like the old wireless adapter was reporting a strong signal but not a totally 'clean' signal. The new adapter may not be getting as strong of a signal, but it is reporting a better quality signal, which generally translates into higher bandwidth/throughput since data doesn't have to be retransmitted due to errors as often.

 

[JackMDS]

Distance is Lear 1 mile is exactly half of 2 miles.

There are phenomenons in nature that are Not linear.

Why? Gods will, or any other religion / science you believe in.

Example: Audio is Not linear if you pump 100 watt you would hear load music.

If you pump 200Watts, you will not hear twice as loud, in matter of fact all Human sensations is not linear.

Human beings are smart they discover that certain phenomenon in Nature follow logarithmic relation, and or other type of mathematical relation.

Hence the DB (deci Bell) concept that defines relations in Logarithmic terms.

Guess what? Wave Signal issues is one of the none Linear phenomenon

If 100W propagate in open space gets, you 1 mile 200W will not get you 2 miles.

It gets much more complicated when the envioroment has Signal obstructions.

Here is an example how these things are calculated.

http://www.demarctech.com/techsupport/cals/link-budget-calcs.htm

Complicated? Sure, unless you spend time learning Electronics.

In any case since it is Network the bars the dbi etc. is not so relevant to the End Users the importance is how much Bandwidth you get: What the Signal Strength Bars mean in Wireless hardware?

:sun: