How to Use Apple’s OS X Lion Wi-Fi Diagnostic Tool
Ever sine Slashdot posted a story regarding the "hidden" Wi-Fi Diagnostic tools found in OS X Lion, I'm getting lots of questions on how to use it. First of all, the tools aren't secret or hidden but simply not documented or highly advertised. In fact there's lots of really interesting tools and utilities in OS X that you probably aren't even aware of!
Anyway, if you don't already know how to find Apple's OS X Lion Wi-Fi Diagnostics tool, Simply click on your hard drive (in the upper right corner) and navigate through the following folders:
System --> Library --> CoreServices
In this folder, double-click on the Wi-Fi Diagnostics tool and you'll see the following:
For most people, you'll be interested in the "Monitor Performance" tool — so make sure that radio button is selected and click "Continue".
The tool will automatically start collecting Wi-Fi performance data such as the one shown here:
But how do I know if I have a good Wi-Fi signal you ask?
Well, to figure this out, you need to look at the "Signal" and "Noise" data and do some quick calculations.
The "Signal" number specifies the signal strength between your Mac and the Wi-Fi access point or router. The higher this number is, the better. But note that these are negative numbers so a Signal of -60 is higher (and stronger) compared to a Signal of -80. The Noise number represents the amount of wireless noise that can interfere with the Signal. In this situation, we want lower numbers. So again, because we have negative Noise numbers, a Noise level of -94 is better than one of -90.
Finally, we can take the Signal and Noise numbers to come up with a Signal-to-Noise ratio (SNR) for our wireless connection. So for example, If I have a Signal level of -60 and a Noise level of -91, the difference between these two numbers is 31. The higher the SNR is, the better the Wi-Fi performance will be. Typically a SNR of 25 or higher will give you great Wi-Fi performance.