Glossary of Terms

Bandwidth

The size (In hertz) of the frequency range that a signal transmission occupies. Typical narrow band signals occupy a 25Khz bandwidth. Spread Spectrum signals can occupy up to 26Mhz in the 902-928Mhz band.

Bridge

An internetworking device that incorporates the first two layers of the OSI model and allows connection of networks or subnetworks with similar architectures.

CSMA/CA

(Carrier Sense Multiple Access/Collision Avoidance) - CSMA is a protocol in which each node senses whether or not a channel is in use before attempting to transmit information.

Direct Sequencing

A spread spectrum technique by which the transmitted signal is spread over a particular frequency range.

FCC

Federal Communications Commission - A federal agency that regulates the use of Radio Frequency equipment.

Frequency Hopping

A spread spectrum technique by which the band is divided into a number of channels and the transmissions hop from channel to channel in a pre-specified sequence.

Interference

A situation that occurs when the RF signals are blocked due to physical barriers such as steel-reinforced concrete floors or collisions of RF signals transmitting in the same band.

Narrow Band

A channel of about 25Khz bandwidth in the RF spectrum. The FCC allocates Narrow Band channels and issues a license to the user. Each user of a specific narrow band frequency range must obtain a license from the FCC to use

OSI

ISO's (International Standards Organization) seven -layer communications network architecture reference model. The seven layers include Application, Presentation, Session, Transport, Network, Data Link and Physical.

Router

An internetworking device which incorporates the first three layers of the OSI model and connects multiple networks together.

Spread Spectrum

A radio data transmission modulation technique by which the transmitted signal is spread over a bandwidth wider than the information bandwidth. Spread Spectrum bands are designated by the FCC and require no user license.
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