Glossary

Bandwidth

The range of frequencies, expressed in hertz (Hz), that can pass over a given transmission channel. The bandwidth determines the rate at which information can be transmitted through the circuit.
ALSO: The information capacity of a communications resource, usually measured in bits per second.

Broadband

A classification of the information capacity or bandwidth of a communication channel. Broadband is generally taken to mean bandwidth higher than 2 Mbps.

CDMA

Code Division Multiple Access -- A way to increase channel capacity by using code sequences as traffic channels in a common radio channel. This technology was originally developed for military use over 30 years ago. Also -- A digital signal multiplexing technique where each signal is split into many chips of data, each of which is tagged with a particular code. During transmission, the chips are spread over a band of frequencies, then reassembled at the receiving end. This technique permits many different signals to be co-located in the same frequency band.

Chip

The time it takes to transmit a bit or single symbol of a PN code.

Cross-correlation

A measure of the similarity of two different signals.

De-spreading

The process used by a correlator to recover narrowband information from a spread spectrum signal.

DSSS

Direct Sequence Spread Spectrum

FHSS

Frequency Hopped Spread Spectrum

FM

Frequency Moduation; modulation of the RF carrier frequency -- another very simple modulation, used today in the FM band.

Frequency

The reciprocal of a signal's period is its frequency (units of Hertz -- or cycles per second -- actually 1/second, dimensionally).

Frequency assignment

Authorization given by a nation's government for a station or an operator in that country to use a specific radio frequency channel under specified conditions.

FSK

Frequency Shift Keying; a digital binary modulation of the RF carrier frequency.

Mbps

One million bits per second; a data rate.

Microwave

A signal in the generic frequency range from above 1 GHz to an upper end of perhaps 30 or 40 GHz. This is the frequency range where coaxial cabled TEM mode signal propagation is viable.

Narrowband

A classification of the information capacity or bandwidth of a communication channel. Narrowband is generally taken to mean a bandwidth of 64 kbps or below.

Noise-like

Having properties that cause the appearance of true random noise.

PM

Phase Modulation; modulation of the phase of an RF carrier.

PN

Pseudo Noise -- a digital signal with noise-like properties. Also -- a wideband modulation which imparts noise-like characteristics to an RF signal.

Wideband

A classification of the information capacity (or bandwidth) of a communication channel. Wideband is generally taken to mean a bandwidth between 64 kbps and 2 Mbps.