Hi Karl, First thing to keep in mind is that it is almost always better to choose one of the channels already in use than to try to squeeze in between. Why? 2 reasons: 1. wifi channels are at least 20MHz wide (802.11n can be 40 MHz) and you need the entire width to be clear of interference/interruptions for communications to work properly. That means when you choose 2412 MHz, your signal actually operates betwen 2402 and 2422 MHz. I.e. overlaps with the 2417 channel (2407 to 2437) by more than half. As a general rule, channel 1, 6 and 11 are widely consider the 'three clear channels' to use. In Australia, we could arguably use 1, 5, 9 and 13 - but since a) most everyone else uses 1,6,11 scheme, and b) using channel 13 means that many international devices will not be able to find your network, the international scheme is the defacto standard even in countries that have channel 12 & 13 available. 2. wifi is designed to 'play nice' with other spectrum users. You may have heard that WiFi is a 'CSMA' - 'MA' is multiple access, which means that all clients share the same access mechanism (i.e. wireless channel) 'CS' is 'Carrier Sense' which means that any device that has data to send will first 'listen' to the access medium to determine whether anyone else is already transmitting before starting to send data. This goes for all participants - access point and client alike. Considering the two points together, carrier sense only works when the selected channel is the same - even 5MHz different is considered nothing but noise - so if there is one channel that is clear, select that one even if there are many other SSIDs using that same channel (there is a reason that there are so many ;-) Next thing worth mentioning is routerOS 'snooper' tool - it produces a report not only nearby SSIDs and Channels, but also how many clients are operating, and how much of the available airtime is in use. This tool will let you work out how much 'capacity' is left for any given channel - for example if there are two potential targets for your selection, you may discover that one of them is already actively in use for 75% of the available time, but the other one is only 15% active. Also, snooper may show you that although channel 1 3 and 5 are in use, the overlapping channel may only be used a small part of the time (i.e. maybe just one AP that no clients ever connect to because it suffers too badly from activity on the channels 1 and 5... Apart from that: 'what Thomas said' - I agree, proximity is king: http://shop.duxtel.com.au/article_info.php?articles_id=48 Cheers! Mike.

-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Karl Auer Sent: Monday, 22 December 2014 10:34 PM To: MikroTik Public Subject: [MT-AU Public] wifi interference - solutions?

Dunno if this list accepts attachments, but if it does, a scan and a spectral- scan are attached.

The scan shows senders on 2412, 2417, 2427, 2437, 2457 and 2462. The spectral-scan shows - well actually I'm not sure what it shows :-)

What's the best way for me to get decent wifi for people associating with this router? At the moment, it's pretty patchy.

I was thinking maybe change to a 10MHz channel width and aim for one of the channels not seen, like 2452, but I don't really know what I'm talking about so was hoping for a clue from someone more, er, clueful.

Regards, K.

-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~ Karl Auer (kauer@nullarbor.com.au) work +61 2 64957435 http://www.nullarbor.com.au mobile +61 428 957160

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