ss telephones using this technology are also avail- able for the consumer market, including wireless PBX systems in office appli- cations. These wireless office spread-spectrum telephone systems have the advantage of adequate power levels without requiring FCC licensing and they are robust against interference and multipath. Wireless point-of-sale (POS) applications also use spread-spectrum radios. These include cash registers, bar-code readers, and menu pads in restaurants, which are, in essence, simple forms of wireless LANs. Also PCMCIA spread- spectrum radia modem cards are available for laptop computers and per- sonal digital assistants (PDAs). Spread-spectrum radios are ideal for home control systems, providing greater security owing to the different codes used for creating the spread- Commercial Applications spectrum signals. Building alarm systems can be made more reliable by attaching to windows and doors small but higher-power unlicensed spread- spectrum radio transmitters that detect unauthorized entry into buildings and send alarm signals to a receiver. 3.2.2 Outdoor Applications In many situations, the local telephone company is unwilling or unable to provide wired voice or data service in a timely manner. Unlicensed spread- spectrum radios are often used as an alternative, providing quick and easy setup of such links without requiring the user to apply for a radio frequency from the FCC. Sometimes, these "bypass" radios are used as emergency backup to wired lines, but in many cases, they are used as a more economi- cal substitute for digital leased lines. Among interesting outdoor applications is the Federal Emergency Management Agency's (FEMA) experimental use of spread-spectrum radios over a 60-mi range (with a relay) to transmit digital video at a full-duplex 256 kpbs data rate. In the Galapagos Islands, spread-spectrum radios are used to link remote scientific stations to the main research center without disturbing the environment with wires. A spread-spectrum radio system in Moscow links compan