{"id":1476,"date":"2011-02-07T12:21:41","date_gmt":"2011-02-07T12:21:41","guid":{"rendered":"http:\/\/mccltd.net\/blog\/?p=1476"},"modified":"2013-04-10T16:04:29","modified_gmt":"2013-04-10T15:04:29","slug":"airpcap-nx-802-11n-and-the-extension-channel","status":"publish","type":"post","link":"http:\/\/darenmatthews.com\/blog\/?p=1476","title":{"rendered":"AirPcap NX, 802.11N and the Extension channel"},"content":{"rendered":"

IEEE 802.11n uses the multiple-input-multiple-output (MIMO) technology that enables spatial signal diversity and spatial signal multiplexing enabling increased range and data transmission rates.\u00a0 802.11n allows use of wider 40 MHz channels to double the bandwidth as compared to the legacy 20 MHz operation.<\/p>\n

AirPcap NX adaptors can be configured to capture data on 40MHz channels but you will need to determine the “extension channel”<\/p>\n

What is an Extension channel?<\/strong>
\nFor 802.11n adapters, use of the Extension Channel enables a \u201cwide\u201d channel to be used. The choices for setting the extension are -1 (the preceding 20MHz frequency band), 0 (no extension channel), or +1 (the succeeding 20MHz frequency band). (The channel of the additional frequency band is called the extension channel).<\/p>\n

\"2.4GHz<\/a>
\nThe AirPcap adaptor configuration Extension Channel list box lets you choose a valid extension channel (above or below) for a given channe (see figure 1 below).<\/p>\n

Not all channels have above and below extension channels: <\/strong><\/p>\n

For example, BG channels 1, 2, 3, and 4 do not have a -1 (below) extension channel. The reason is that the center frequencies of the primay and extension channels need to be separated by 20MHz. So if 4 were the primary channel, channel 1 (which is the lowest BG center frequency) is only 15 MHz below channel 4.<\/p>\n

\"AirPcap<\/a>

Figure 1<\/p><\/div>\n

\"airpcap-nx-1\"<\/a><\/p>\n

\"airpcap-nx-3\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

IEEE 802.11n uses the multiple-input-multiple-output (MIMO) technology that enables spatial signal diversity and spatial signal multiplexing enabling increased range and data transmission rates.\u00a0 802.11n allows use of wider 40 MHz channels to double the bandwidth as compared to the legacy 20 MHz operation. AirPcap NX adaptors can be configured to capture data on 40MHz channels […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[53],"tags":[59],"_links":{"self":[{"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1476"}],"collection":[{"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1476"}],"version-history":[{"count":5,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1476\/revisions"}],"predecessor-version":[{"id":1749,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1476\/revisions\/1749"}],"wp:attachment":[{"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1476"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1476"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/darenmatthews.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1476"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}