AirView Wireless Spectrum Analyzers
AirView is a family of low-cost wireless spectrum analyzer products sold by Ubiquiti Networks. AirView2 covers the 2.4 GHz band used by Wi-Fi while Airview9 covers the 900 MHz band used by cordless phones and some other consumer gadgets.
To use AirView, simply plug its USB stick into a portable computer (Windows, Apple or Linux) and begin scanning the vicinity for wireless signals. If you'd prefer to not lug a computer around the house, you can also purchase an external antenna to use with either of these products instead. These tools produce charts like the one shown at right for Airview2, which break down the levels of wireless signal traffic and interference per channel, helping you set the optimal Wi-Fi channel number on your router and other wireless home network equipment.
→ See also - Find Wireless Interfererence with Wi-SpyAirView2 Spectrum Analyzer - Channel Usage Chart - Image: Ubiquiti Networks (ubnt.com)


Acquiring a spectrum analyzer can now be done by purchase in a cheap price as well as by rental service.