Mac OS X is full of surprises and today I’m going to share one trick that can save you a lot time. The next time you’re noticing slow internet connectivity on your Macbook Air, Mini, or Pro, check out this quick tip.
But before we get into the gritty details you know I always like to give you the background knowledge. I like to set the stage so you can have everything you need to really understand what’s going on with your computer and your wireless connection.
Your TV has multiple channels such as HBO, Nickelodeon and ABC. Well guess what? so does your wireless router!
It uses a set of frequency channels for optimal data connectivity.
Currently, all 802.11a, 802.11b, 802.11g and 802.11n devices play around in the 2.4GHz frequency band. 802.11a plays the drums. 802.11b plays the bass and 802.11g and 802.11n are the backup singers.
hah just kidding – I just couldn’t resist playing with on the homonym “band“.
Anyway, 802.11a, b, g, and n devices live in a 100MHz stretch of frequencies squeezed between 2400MHz and 2500MHz.
By the way, to learn the basics of Wi-Fi frequencies, check out the post I did earlier this week in my three part series on how Wi-Fi works.
The FCC sliced up the frequency space into 14, 20Mhz wide channels and basically said: have fun.
100Mhz divided by 20Mhz gives us 5 channels. But the FCC dices the space into 14 sections which means almost all the channels are going to overlap. (because they all need to fit within that 100Mhz cap)
Most of the channels overlap with four other channels which is really bad for Wi-Fi communications because it creates signal interference. On your TV back in the pre-cable days, this would manifest itself as evenly spaced, thin diagonal lines scrolling above the picture.
In wireless local area networks (WLANs), signal interference can come from baby monitors, cordless phones, bluetooth headsets and even people in crowded rooms.
Believe it or not, the human body is about 50 to 75 percent water. And water gets in the way of Wi-Fi signals and transmission speeds!
Most people don’t realize this. So now you can rebuke your fat girlfriend for stuffing her face with Doritos everyday because she’s clogging up your network connection.
hahaha man I’m so mean.
So what’s the best channel?
In the 2.4Ghz space, channels 1, 6 and 11 are ideal because they’re far apart where overlap is impossible.
But here’s the catch, and this is why you may need to use the Apple Wireless Diagnostics tool to figure out your optimal channels:
The best Wi-Fi channels are contingent on the channels your neighbors are using.
If you live in a dense city apartment or a crowded neighborhood, it might still have a crappy wireless connection when using channel 1, 6 or 11.
Because, if the guy next to you is using a channel next to 1, 6 or 11 then you’ll get interference because the channels will overlap.
For example, if you’re using channel 6 and your neighbor is on channel 7 you’ll feel it. Your Wi-Fi connection will have all kinds of connectivity issues.
The good news is that this more germane to people with sheet rock walls and thin floors. If you have solid dividers like stone and brick then you can probably use the same channels all day long because the signals are contained.
5Ghz to the rescue!
The nice thing about 802.11n (and 802.11ac) is that it can also use the 5GHz frequency spread. 5Ghz is generally better because you get 23 non-overlapping channels which means there’s very little interference.
Microwaves and cordless phones don’t operate in this space so you’ll never have your network drop when your mom calls or you microwave that chocolate dipped orange for your corpulent spouse. (hey you got to get them to eat fruits some way right?)
Of course the trade off is that you get less range with 5GHz – but is that really a problem?
Let’s see here:
Shorter ranges but with reliable connections versus longer ranges but with unreliable connections? Hmm, I’m going with the former.
Finding the best channel in Yosemite
Mac OS X Yosemite has a ultra secret tool called Wireless Diagnostics that lets you scan for the best 2.4 GHz and 5 GHz channels. You can then login to your router and set your channels to match and you’ll be golden. Well, at least until your conniving neighbor figures out which channel you’re using so he can drop your connection by picking one next to yours.
Your voyage to wireless channel nirvana begins with the Wi-Fi icon in the upper right corner of the screen.
The secret is to press and hold down the Option key while clicking the Wi-Fi icon.
You’ll see a new menu emerge with a bunch of appetizing settings about the Wi-Fi network you’re currently associated with.
Ignore all that stuff and click Open Wireless Diagnostics… at the top of the menu list.
You’ll see a welcome wizard shoot on the screen.
Ignore this too.
Just press Command + 4 to bust open the Scanner.
Yup, Mac OS X comes with a built in wireless network scanner. Who knew?
In the Scan window, you can click Scan Now in the bottom right corner to launch your scan.
You’ll see a bunch of columns with a bunch of information that might give you a migraine. But it’s actually not that difficult to understand.
The BSSID (Basic Service Set Identifier) is just a fancy term for the specific access point that is broadcasting the network name.
For example, most companies have multiple access points all with the same SSID (network name). So how do you know which physical access point your computer is associated with? That’s what the BSSID is all about. Technically, it’s the MAC address (physical address) of the access point.
The Security column shows you the type of Wi-Fi security in effect for the access point. WPA2 Personal and WPA2 Enterprise are the strongest.
The Protocol column shows you a list of compatible protocols so there’s nothing exciting here.
But the last three are columns are pretty interesting.
RSSI is the Received Signal Strength Indication. Different manufactures have different meanings for the negative numbers here but in general, the RSSI is a number on a scale from 0 to -100. Here’s the bottom line here: The closer the number is to 0 the closer your computer is to the access point. An ideal RSSI is typically between -50 and -60.
If you scroll to the right you’ll see more columns.
The Noise column is a negative number that represents interference in decibels full scale (dBFS). Keep in mind, I’m not talking about the decibels used to measure sound pressure (like your 2 year old screaming at the top of his lungs at that funeral); that kind of dB is different than dbFS. Music and audio is based on dB SPL (sound pressure level) – these are two disparate things with the same name. It’s confusing I know but you don’t need to know the details.
The main thing to keep in mind is that the dBFS value in the Noise column represents how much crap has adulterated the signal. Stuff like other wireless devices in the same transmitter range can can drive this value up (meaning closer to 0.)
You want the noise value to be in the -90 to -100 range. Anything greater than that (meaning closer to 0) is usually not good because there’s too much interference in the way. (like your fat spouse)
The last columns, Channel, Band and Width are self explanatory so I won’t go over those.
The only thing we care about is that small summary table in the left corner of the window.
If the Current Channel number isn’t listed in the Best 2.4GHz or Best 5GHz rows, you know you need manually set the Wi-Fi channel on our router to one of those Best values.
If you’re using an AirPort extreme router, you can press Command + Space and type “Airport”. Then you can click Edit, hit the Wireless tab and choose the Wireless Options button to make the channel adjustments.
The Bottom Line
The next time your wireless network starts behaving with caprice, Option Key click the Wi-Fi icon and press Command + 4 to see what’s going on. Chances are you just need to change the channel!
That’s all I have today but you can get more stuff like this if you join my email list. Go ahead and drop your name and email address in the form in the right rail (you may have to scroll up to see it) and I’ll give you my free 40 page Google Chrome eBook. I’ll also send you valuable content that I don’t post to my blog.
Don’t delay! Act now!
You can picture me with a stupid “used car” salesman face as I said that right? hahaha.
Thanks for reading. I’ll see you on my email list buddy.