Installing a third-party USB wireless adapter
You can capture wireless 802.11 traffic on systems lacking built-in wireless by installing a third-party USB wireless adapter. Wireless access point statistics and other features become usable as well. Installing a special driver on your USB wireless adapter is necessary.
Prerequisite(s):  
The USB wireless adapter is only supported on systems running Windows Vista or 7 (32- or 64-bit).
 
Caution: For some wireless adapters you must install the software for the USB wireless adapter before you attach the adapter to your computer. This is not an Observer requirement, but one of the wireless adapter. If you attach the USB wireless adapter before installing the software, unplug the USB adapter, uninstall the software, restart your system, and then proceed with step 1.
Note: If using a Belkin N600DB USB wireless adapter, only revision number “F9L1101v1” is compatible. These adapters have a Broadcom chipset. The second revision, “F9L1101v2” does not have a Broadcom chipset and is incompatible.
1. Install the software that came with your USB wireless adapter.
2. Insert the USB wireless adapter into your system.
3. Choose Control Panel > Network and Sharing Center > Change adapter settings and then select your USB wireless adapter. Right-click and choose Properties.
4. From the Networking tab, click Install > Service > Add. Click Have Disk and locate this file:NiNdisMon.inf
64-bit: C:\Program Files\Observer\DRIVERS\Wireless
32-bit:C:\Program Files(x86)\Observer\DRIVERS\Wireless
5. Click OK to install the software as a Windows service.
6. Restart your system.
Restarting allows the software and adapter to be fully recognized by your system and the Windows service to start. Observer will not be able to use the wireless adapter until you restart.
7. Start Observer, select the probe instance you want to associate with the USB wireless adapter.
8. On the Home tab, in the Probe group, click Setup > Select NIC.
9. Choose the USB wireless adapter you just installed.
 
The probe instance is now configured to use the USB wireless adapter. You can confirm this because the word "[Wireless]" appears after the probe instance name, and the Wireless 802.11 tab of the probe instance is visible.