These spectral masks are
defined in IEEE specification 802.11a, 802.11b, and 802.11g. Wireless LAN (WLAN) transmitters are required to meet
these masks and
FCC Part 15
(15.247, 15.205, and 15.209) unlicensed equipment specifications simultaneously.
These spectral masks can of course be found in the IEEE802.11 document, but they are sometimes difficult in a