User's Manual

SPEEDLAN 9200 User Guide Part # 34357-MNL Rev.03
Glossary-15
Pseudo-random Noise code (PN code)
A high rate digital code that mimics random noise-like properties. It is multiplied with a lower rate data
signal in order to achieve spread spectrum transmission signals. The receiver then multiplies the same code
back into the transmission to recover the data signal.
Public Switched Telephone Network (PSTN)
This refers to a worldwide voice telephone network accessible to all those with telephones and access
privileges.
Quadrature Amplitude Modulation (QAM)
It’s a high-density modulation that uses phase and amplitude modulation at the same time. It’s used in
OFDM, and modulators require a high SNR to provide a stable signal recovery rate.
Quadrature Phase Shift Keying (QPSK)
Phase-shift keying in which there are four phase states or positions in the time or frequency domains within a
single period.
Radiation
The emission of energy from a generator to a transmitter.
Radiation Pattern
An illustration of the energy level radiated by an antenna in every direction.
Radio Frequency (RF)
The frequency at which microwave systems transmit.
Received Signal Strength Indicator (RSSI)
The RSSI Voltage provided at the output of the RF Unit that is used to indicate the RF Input Level.
Reflection
The sharp change in direction of a wave after hitting an obstruction in its path.
Refraction
The change on the energy’s propagation direction as it travels through different density medium.
Reliability
A measure of the percentage of time the system is operating. Reliability is usually a measure of both the avail-
ability of the signal and the MTBF of the equipment.