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Is there any windows utility to display the wireless channels are currently in use by the available wireless networks? I'd like to be able to see what existing channels are using so I can try to minimize interference on a new access point without a lot of trial and error.

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up vote 3 down vote accepted




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inSSIDer was even more useful than I expected, thanks. – DrStalker Mar 23 '10 at 7:27
Glad to help... – joeqwerty Mar 23 '10 at 15:41

If you're looking for a cloud-based solution, there's a free, internet based, WiFi Stumbler.

Full Disclosure: I work for Meraki.

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That is so cool! For anyone who thinks, "How could it possibly work in a web browser?", it is running a Java applet. Very, very nice. – Clinton Blackmore Jun 2 '10 at 15:15

If you're in 2.4GHz, please be aware of a few things:

  1. There are lots of non-802.11 interferers in that band, so just looking at 802.11 networks doesn't necessarily give you a good picture of the band usage. Bluetooth, Wiimotes, microwave ovens, and many cordless phones, baby monitors, wireless webcams / security cams, and wireless room-to-room A/V senders, among many other things, use the same 2.4GHz ISM band as 802.11. None of these other sources of interference would be detected by your typical Wi-Fi network scanner. One special note on cordless phones: Even if they say 5.8GHz, they may only use that in the base-to-handset direction; many such phones still use 2.4GHz in the handset-to-base direction because it requires less power thus less battery usage. Sometimes you can't tell this from the box at the store; it's not until you read the FCC regulatory information fine print at the back of the user manual that you discover this.

  2. Anyone doing HT40 (40MHz-wide 802.11n channels) is taking up two contiguous non-overlapping channels, leaving at most 1 channel (at least in the North America / FCC 11-channel plan) unaffected. For example, if it's doing control on channel 1, channel 5 will be its extension channel, leaving only channels 10 and 11 unaffected. If they're a real jerk and using, say, channels 4 and 8, it doesn't leave any channel unaffected. If your 802.11 card is not N-capable or your WiFi network scanner app is not HT40-savvy, it might not show you this information. I believe that "Super-G" 108mbps equipment (from back before the MIMO/802.11n days) also bonded two contiguous channels together, and might not show up in your typical WiFi network scanner app as occupying both channels.

  3. Simply seeing another network in a scan doesn't mean it will have any real effect on you. It may only mean that you can occasionally see a really weak beacon or probe response from a distant network. Or even if it's a nearby network, it may be sitting idle all the time.

If you really want to get a proper picture of your RF environment, consider getting an actual spectrum analyzer such as a MetaGeek Wi-Spy.

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+1 for great points and in particular Wi-Spy - great little gadget at a fraction of the cost of most spectrum analyzers. – Helvick Mar 24 '10 at 20:43

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