User's Manual

The frequencies set aside for Industrial, Scientific and Medical (ISM) use have
become known as the unlicensed bands, or license-free bands. In many
countries the ISM band is still a licensed band, but used for the same purposes.
For example, the service provider may be licensed to offer service in the ISM
band, even though a user buys a PC card at a store, is not licensed, but is a
subscriber to the service.
10.2 FCC Rules for use of ISM band
The Federal Communications Commission (FCC) has set down Rules and
Regulations for using the ISM bands.
There are many ISM bands, but the ones that have been most popular are:
a) 902 - 928 MHz
b) 2.400 - 2.4835 GHz
c) 5 GHz
The 2.4 GHz band has gained popularity through the emergence of the IEEE
802.11b/g devices, also called Wi-Fi. These are in laptop computers, PDAs and
other devices. Users link their laptops to Wi-Fi Access Points, often called “Hot
Spots”.
The 5 GHz band is also gaining popularity with IEEE 802.11a devices, but some
lab tests have shown that 802.11g devices outperform the 802.11a, and these
have cast doubt over the growth of the 802.11a devices.
Part 15 of the FCC Rules and Regulations dictate most of the RF characteristics
of the unlicensed devices:
1. Frequency band
2. Transmitter power (Intentional radiation)
3. Out-of-band emissions (Unintentional radiation)
4. Antenna gain/directionality
5. Method of measuring and other parameters
The transmitter power and sub-band frequencies are shown in Figure 10-4.
ARCXtend manual, August 2003 10-3