|
Directional Siren: A Siren that radiates most of
its sound in a beam pointing in a specific horizontal direction.
back
to top
Electronic Siren: A siren that produces tonal
sounds by amplifying the output of an electronic signal generator
and broadcasting the amplified signal from one or more electrodynamic
loudspeakers.
back
to top
Halogen: High pressure tungsten filament lamps containing
halogen gases. The halogen gases allow the filaments to operate
at higher efficacy than incandescent lamps. Halogen lamps
also provide brighter, whiter light with better color characteristics,
longer service life and improved energy efficiency.
back
to top
Horizontally Omni Directional Siren: A siren
that radiates sound approximately uniformly in all horizontal
directions from the siren.
back
to top
LED Light: A light-emitting diode (LED) is a semiconductor
device that emits incoherent narrow-spectrum light when electrically
biased in the forward direction. This effect is a form of
electroluminescence. The color of the emitted light depends
on the composition and condition of the semiconducting material
used, and can be infrared, visible or near-ultraviolet.
back
to top
Lightbar: A light bar (or lightbar) is a device designed
to make an official vehicle easily identifiable. Lightbars
are fitted to nearly every emergency vehicle and most utility
vehicles for the purpose of alerting other vehicles and pedestrians
of emergency situations or other road hazards.
back
to top
Lumens: The light output from a lamp (bulb or tube)
is expressed in lumens. A 100-watt incandescent bulb produces
1750 lumens; a 40-watt cool white fluorescent produces 3150
lumens. Lumens can be thought of as the measurement for the
flow rate of light. The efficiency of light sources is measured
by the amount of light emitted for each watt of power used,
or lumens per watt. In the above example, a 100-watt incandescent
has 17.5 lumens per watt while the 40-watt fluorescent has
78.75 lumens per watt.
back
to top
Mechanical Siren: A siren that produces tonal
sounds by periodically interrupting a flow of compressed air.
Mechanical sirens may be motor or engine driven, and the air
compressor may be integral with or separate from the flow
interrupter.
back
to top
Mechanical/Electronic Siren: A siren that
uses a tone generator driven by mechanical means, and the
tone generator output is applied by direct connection to loudspeakers,
or through one or more electronic amplifiers to loudspeakers.
back
to top
Rotating Siren: A directional siren that contains
a mechanism to slowly rotate its beam of sound about a vertical
axis.
back
to top
Searchlight: A searchlight is an apparatus
with reflectors for projecting a powerful beam of light of
approximately parallel rays in a particular direction, usually
devised so that it can be swiveled about.
back
to top
Strobe Light: A strobe light is a device
which produces regular pulses of bright light without the
long period of decay in intensity at the end of a pulse, such
as happens with ordinary incandescent light bulbs. It can
cause a motion to seem to slow down due to aliasing. It was
invented by Harold Edgerton.
back
to top
Two-Tone Siren: A siren designed to produce
tonal sound with two simultaneous fundamental frequencies.
The two fundamental frequencies are not harmonically related.
back
to top
Watts: A measure of power or the rate of energy consumption
by an electrical device when it is in operation, calculated
by multiplying the voltage at which an appliance operates
by the current it draws (Watts = Volts X Amperes).
back
to top
|
