Campbell Scientific RF320-Series Ritron VHF/UHF Radios - Manual (Page 31)

Appendix A. Glossary
Insertion Loss: The loss in signal strength due to the insertion of a device in
series with a signal path. Typically measured over the intended operating
frequency range of the device and expressed in dB.
Isotropic: A theoretical “isotrope” is a single point in free space that radiates
energy equally in every direction similar to the sun.
Lightning Suppressor: A device whose purpose is to eliminate transients on a
conductor that are induced by nearby lightning activity.
Line-of-Sight: A straight path between a transmitting and receiving antenna
that is unobstructed by intermediate topography. RF telemetry systems operate
best and sometimes require line-of-sight transmissions. The use of repeater
stations can overcome line-of-sight interruptions.
Link Budget: A mathematical model of a wireless communications link that
accounts for a wide variety of factors that affect operating range and
performance. (See also Fade Margin.)
Modulate: The process of imprinting information in the form of audio or
digital data onto the transmitter’s carrier frequency.
Multipath Interference: Signal reflections and delayed signal images that
interfere with the desired un-delayed and larger desired signal. Causes errors in
digital transmission systems.
Narrowband Channel: That part of the RF spectrum occupied by the radio’s
emissions having a maximum band width of 12.5 kHz centered about the
channel frequency.
Noise Floor: The sum of all measurable noise in the receiver attributable to
thermal noise, cosmic noise, atmospheric noise, and unwanted signals. As a
practical point, the Noise Floor is the signal level where noise is the dominate
signal and no desirable signal can be distinguished.
Noise Squelch: A receiver function whereby the audio or data output is
inhibited whenever the received signal strength is below a set threshold. The
purpose is to eliminate the output of noise when no usable signal is present at
the receiver’s input.
Omnidirectional Antenna: An antenna that radiates or receives RF energy in
a 360 degree pattern about an axis.
Path Loss: The weakening of a signal over its path of travel due to various
factors like terrain, obstructions and environmental conditions. Measured in
dB.
Point-to-Point: A communications topology that links one single station to
another.
Point-to-Multipoint: A communications topology where a central base station
communicates with multiple repeaters or remote stations, often simultaneously.
Power Meter: A device used to measure radio frequency energy in Watts into
a standard Impedance like 50 ohms. (See also Wattmeter.)
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