RAW Computing

Scan for wireless networks on the Apple Mac

Wireless networks are everywhere - in your home, at work, and in public places. If you have an iMac, MacBook, iPhone, iPod Touch or iPad, you have a device that is capable of connecting with a Wi-Fi hotspot. Wi-Fi is one of the best inventions for years. However, there are certain problems that can arise, such as poor connectivity, weak signals and intermittent access. Now it may be because you are too far from the wireless access point and the signal is too weak, but it could be because of interference. When there are two or more wireless networks, their signals can interfere with each other and cause reception problems.

There are two things you can do and if you are in a public place or work, you may have access to several Wi-Fi access points and you should connect to the one with the strongest signal. If you are at home, you could change the channel that your wireless access point (router with built in Wi-Fi) uses. Pick a channel that's as far away from your neighbours as possible. Let's see how to scan for wireless networks.

If you click the Wi-Fi icon in the menu bar at the top of the screen you'll see a list of the networks that are available. Apart from listing their names, it doesn't really help when it comes to choosing the best one or for finding out why the Wi-Fi network you use is so poor. The Wi-Fi icon next to the name gives you an indication of the signal strength, but it's not perfect.

A better display is available if you hold down the Option key as you click the Wi-Fi icon in the menu bar. You can see more information about the wireless network you are connected to. Let the mouse hover over the other networks listed and you can see information about them without having to connect to them.

OS X wireless network

Wireless utilities

There are several utilities that can provide similar information and more, but in a better format. A good one is iStumbler. It's a free open source program, as is KisMAC, which performs a similar job. There are utilities in the Mac App Store too, for example, search for WiFi Scanner and WiFi Explorer. They aren't free, but they are very cheap.

iStumbler scans for networks and displays a list of every one that it finds. It doesn't just list them though, it displays lots of useful information, like the security used, protocol, signal strength, noise, channel, and much more. It can even work out your location and display it on Google Maps, although it's hard to think of a reason why you would want to. Maybe if you get lost!


The screen shot shows what could be seen at a Starbucks coffee shop in a shopping mal using a MacBook. Armed with this information, you can easily see which networks you can log on to (check the Secure column) and which has the best signal and least interference (Level, Signal and Noise columns).

You won't find this many networks at home, but if there are two or more, you should look at the Channel column. The channel you use for your wireless router should be as far from your neighbours as possible. The worst situation is when you both use the same channel. The signals will clash and your wireless connection will be poor.

Channels 1, 6 and 11 or usually recommended because they are as widely spaced as possible and are widely supported. Changing the wireless channel involves changing the wireless router configuration and that depends on what hardware you have. Each device is different, so check your manual.

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