GENERAL ACRONYMS FOR EMS
COMMUNICATIONS
A
AA—above average terrain
AC—alternating current
ACD—automatic call distributor
ACLS—advanced cardiac life support
ACSB—amplitude compandored single-
sideband
ADP—automatic data processing
AGL—above ground level
ALS—advanced life support
ALERT—automatic law enforcement
response team
ALI—automatic location identification
AM—amplitude modulation
AMSL—above mean sea level
ANI—automatic number identification
APB—all points bulletin
APCO—Associated Public-Safety
Communications Officers
ASCII—American Standard Code for
Information Interchange
ASTM—American Society for Testing and
Materials.
ASTRA—Automated Statewide
Telecommunications And Records Access
ATLS—Advanced Trauma Life Support
AT&T—American Telephone and
Telegraph Company
AVC—automatic volume control
AVI—automatic vehicle identifications
B
balun—balanced-to-unbalanced line
transformer
BCD—binary coded decimal
BFO—beat frequency oscillator
BIT—binary digit
BLS—basic life support
BPS—bits per second.
BSC—binary synchronous communications
C
C—Celsius
CAD—computer –aided Dispatch
CB—citizens band
CCH—computerized criminal history
CCITT—International Telegraph And
Telephone Consultative Committee
CCSA—common control switching
arrangement
CCTV—closed circuit television
CCU—Coronary Care Unit or Critical Care
Unit
CDC—Cooperative Dispatch Center
CG—Channel Guard(R) Trademark of
General Electric
CMED—Central Medical Emergency
Dispatch
CMR—Common Mode Rejection
CMRR—Common Mode Rejection Radio
CNIL—Calling Number Identification and
Location
CO—Central Office
COG—Council of Governments
COR—Coronary Observation Radio
CPR—cardiopulmonary resuscitation
CJIS—Criminal Justice Information System
CTCSS—Continuous Tone Controlled
Squelch System
D
dB—decibel
dBm—decibel reference to 1 mW.
dBu—decibel referenced to 1 mV/m
dBv—decibel referenced to 1 V
dBW—decibel referenced to 1 W
DC—direct current
DCS—Division of Computer Services
DDD—direct distance dialing
DID—direct inward dialing
dod—direct outward dialing
DOD —US Department of Defense
DOT—US Department of Transportation
DRG—diagnosis related grouping
DP—double pole
DPDT—double pole double throw
DTMF—dual-tone multi-frequency
DPST—double pole single throw
E
EACOM—emergency and administrative
communications system
EAS—extended area service
E & M-–the receive and transmit leads of a
signaling system
EAX—electronic automatic exchange
ECC—emergency communications center
EDP—electronic data processing
EIA—Electronic Industries Association
EMD—emergency medical dispatcher
EMF—electromotive force
EKG—electrocardiogram
EMDPRS—emergency medical dispatch
priority reference system
EMS—emergency medical service
EMSS—emergency medical service system
EMT—emergency medical technician
EMT-B—emergency medical technician-
basic
EMT-D—emergency medical technician-
defibrillator
EMT-I—emergency medical technician-
intermediate
EMT-P—emergency medical technician-
paramedic
EOC—emergency operations center
EOM—end of message
ERCC—emergency resource coordination
center
ERP—effective radiated power
ESS—electronic switching system
EST—Eastern Standard Time
ETA—Estimated Time of Arrival
ETV—Educational Television
F
F—Fahrenheit
FCC—US Federal Communications
Commission
FCCA—Forestry Conservation
Communications Association
FEMA—Federal Emergency Management
Agency
FET—field-effect transistor
FM—frequency modulation
Freq.—frequency
FORTRAN —formula translation
(computer language)
FSK—frequency-shift keying
FX—foreign exchange
G
GE—General Electric
GESS—General Electric Service Station
GFW—ground fault warning
GHZ—gigahertz (1000 MHz)
GIGO—garbage in, garbage out
GMT—Greenwich Mean Time (Zulu)
GSA—General Services Administration
GT&E—General Telephone and
Electronics
H
HEAT—hospital emergency administrative
radio
HF—high frequency
HYSIS—highway safety information
system
HV—high voltage
Hz—hertz
I
I—current in amperes
IAFC—International Association of Fire
Chiefs
IACP—International Association of Chiefs
of Police
IC—integrated circuit
ICO—individual channel oscillator
ICOM—integrated circuit oscillator module
ICU—intensive care unit
ICX—intercity exchange link
IEEE—Institute of Electrical and Electronic
Engineers
IF—intermediate frequency
IMSA—International Municipal Signal
Association
IMTS—improved mobile telephone service
IRAC—Interdepartmental Radio Advisory
Committee
ISPERN—Illinois State Police Emergency
Radio Network
IT&T—International Telephone and
Telegraph Corporation
ITU—International Telecommunication
Union
J
JAN—Joint Army-Navy Specifications
JETEC—Joint Electron Tube Engineering
Council
JFET—junction field-effect transistor
UPS—uninterruptible power supply
USIT—US Independent Telephone
Association
USFS—US Forest Service
Journal of Emergency Medical Services
K
UPS—uninterruptible power supply
USIT—US Independent Telephone
Association
USFS—US Forest Service
kbps—kilobits per second
kHz—kilohertz (1000hertz)
L
LATA—local access transport area
LMR—land mobile radio
LEAA—Law Enforcement Assistance
Administration
LETS—Law Enforcement Teletypewriter
Service
LORAN—long range navigation
LSI—large scale integration
LOS—line of sight
LRO—lead regional organization
LSU—life support unit
M
MAST—Military Assistance to Safety and
Traffic
MCCU—mobile coronary care unit
MF—medium frequency
MHz—Megahertz
MICT—Mobile Intensive Care Technician
MICU —Mobile Intensive Care Unit
MRCC—Medical Resource Coordination
Center
N
NABER—National Association of Business
and E Radio, Inc.
NCIC—National Crime Information Center
NCMCN —North Carolina Medical
Communications Network
NEAR—national emergency aid radio
NHTSA—National Highway Traffic Safety
Administration
NLETS—national law enforcement
telecommunications system
NPA—Number Plan Area
O
O-D—origin-destination
ONI—operator number identification
OTP—Office of Telecommunications
Policy
P
UPS—uninterruptible power supply
USIT—US Independent Telephone
Association
USFS—US Forest Service
PABX—Private Automatic Branch
Exchange
PBX—Private Branch Exchange
PL—Private Line(r) Trademark of Motorola
PM—Pulse Modulation
PSAP—public safety answering point
PSCC—Public Safety Communications
Council
PTT—Press to Transmit or Push to Talk
Q
QEI—quantifiable evaluation indicator
R
RCU—remote control unit
RF—radio frequency
Rx—receive
S
SERS-Special Emergency Radio Service
SIRSA—Special Industrial Radio Service
Association
SMR—Specialized Mobile Radio
SMSA—standard metropolitan statistical
area
SPA—State Planning Agency
SWR—Standing Wave Radio
T
TASI—time assignment speech
interpolation
TCAM—telecommunications access
method
TLOF – Touchdown Liftoff Area
Telco—telephone company
TPL—terminal per line
TPS—terminal per station
Tx—transmit
U
UHF—ultra high frequency
UL—Underwriters Laboratories, Inc.
UPS—uninterruptible power supply
USIT—US Independent Telephone
Association
USFS—US Forest Service
V
V—volts
VAC—volts, alternating current
VDC—volts, direct current
VHF—very high frequency
VOM—volt-ohm meter
VOR—voice operated relay
VOX—voice operated switch
VSWR—voltage standing wave ratio
VTVM—vacuum tube voltmeter
VU—Volume Unit
W
WATS—Wide Area Telephone Service
WECO—Western Electric Company
WPM—words per minute
X
Xcvr.—transceiver
Xfmr.—transformer
Xmit.—transmit
Xmtr—transmitter
Xtal—crystal
Z
Z—impedance
ZULU —time zone at Greenwich, England
FCC CODES AND NAMES OF
RADIO SERVICES
industrial:
IB—business
IF—forest products
IM—motion picture
IP—petroleum
IS—special industrial
IT—telephone maintenance
IW—power
IX—manufacturers
IY—relay press
Motor Carrier:
LI—interurban passenger
LJ—interurban property
LU—interurban passenger
LV—urban property
Land Transportation:
LA—automobile emergency
LR—railroad
LX—taxicab
Public Safety:
PF—fire
PH—highway maintenance
PL—local government
PP—police
PO—forestry conservation
PS—special emergency
RS—radio location
ZA—general mobile
Classes of Radio Stations (FCC):
FB—base
FB2—mobile relay
FB4—community repeater
FX1—control
MO—mobile
MO3—mobile/vehicular repeater
FXO—operational fixed
FX2—fixed relay
FX—fixed
FLT—auxiliary test
FXY—interzone
FXZ—zone
LR—radio location
MR—radio location mobile
806-821/851-866 MHz Bands:
Conventional Category Trunked
GB business YB
GO industrial/land transportation YO
GP public safety/special emergency YP
GX commercial (SMRS) YX
292-930 MHz Band:
GS—private carrier paging systems
GLOSSARY
A
acoustic feedback—The transfer of sound
waves from a loud speaker or end terminal
to any previous component within an audio
system.
activity—The expenditure of time and
resources.
adapter—A device used for changing the
terminal connections of a circuit or part to
connect to another circuit or part with unlike
connections.
alphabet, phonetic—A method of passing
alphabetic information substitution over a
poor communication path with word
substitution for letters. One phonetic
alphabet is: Alfa, Bravo, Charlie, Delta,
Echo, Foxtrot, Golf, Hotel, India, Juliett,
Kilo, Lima, Mike, November, Oscar, Papa,
Quebec, Romeo, Sierra, Tango Uniform,
Victor, Whiskey, X-ray, Yankee, Zulu.
American Standard Code for Information
Interchange (ASCII)—An eight-level code
for data transfer adopted by the American
Standards Association to achieve
compatibility between data devices.
amplitude compandored single-
sideband—A form of sideband modulation
used for narrow channel transmission that
incorporates a pilot tone.
amplitude modulation(AM)—Modulation
in which the amplitude of the carrier-
frequency current is varied above and below
its normal value in accordance with the
audio, picture, or other intelligence signal to
be transmitted.
analog—Physical representation of
information such that the representation
bears an exact relationship to the original
information. Pertaining to data in the form
of continuously variable physical qualities
analog communication—System of
telecommunications used to transmit
information other than voice which
is sometimes used in telemetry.
antenna—A system of wires or electrical
conductors employed for reception or
transmission of radio waves. Specifically, a
radiator that couples the transmission line or
lead-in to space for transmission or
receptions of electromagnetic radio waves. It
changes electrical currents into
electromagnetic radio waves and vice versa.
antenna, isotropic—A theoretical antenna
with identical radiation in every direction.
antenna, parabolic—A directional antenna
with a radiating(or receiving) element, and a
parabolic reflector that concentrates the
power in a beam.
antenna polarization—The direction of the
radiated electrical field in relation to the
surface of the earth. Generally vertical in
mobile radio use.
arc—A discharge of electricity.
arrester, lightning—A device designed to
protect electrical equipment or property
from damage by lightening.
assigned frequency—The frequency
appearing on a station authorization from
which the carrier frequency may deviate by
an amount not to exceed that permitted by
the frequency tolerance.
Associated Public-Safety
Communications Officers (APCO)—A
non-profit public safety radio users group
composed of administrators and
communications technical, operations, and
command personnel.
ASTM—A scientific and technical
organization formed for the development of
standards on characteristics and performance
of materials, products, systems, and
services.
attack time—The interval required after a
sudden increase in input signal to a
transducer (transmitter, receiver, etc.) to
attain a percentage of final output level due
to this increase.
attenuation—The decrease in amplitude of
a signal during its transmission from one
point to another. It may be expressed as a
ratio or, by extension of the term, in
decibels.
attenuator—A device for reducing the
energy of a wave without introducing
distortion. Also called a pad, gain control,
level adjustor, volume control, etc.
audible signal—A buzzer, bell, or other
audible sound device that indicates an
incoming call.
audio—Pertaining to frequencies
corresponding to normally audible sound
waves. These frequencies range from 15 to
20,000 Hz.
aural—Pertaining to the ear or sound.
automatic gain control (AGC)—A receiver
circuit that maintains the output constant
with wide variations in the in the receiver
input level.
automatic volume control (AVC)—A self-
acting gain control which maintains the
output of a receiver constant despite
variations in received signal strength.
automatic number identification (ANI)—
Equipment for recording the calling party’s
number without operator intervention.
B
back bone—A point-to-point
communications system utilizing several
stations.
back-to-back repeater—A repeater
consisting of a receiver and transmitter with
the output of the receiver connected directly
to the input of the transmitter.
band (radio frequency)—A range of
frequencies between two definite limits. By
international agreement, the radio spectrum
is divided into nine bands. For example, the
very high frequency (VHF) band
extends from 30 MHz to 300 MHz.
bandpass filter—Passes frequencies within
a specified band, and attenuates all
frequencies outside that band.
bandwith—(1) The width of a band of
frequencies used for a particular purpose, (2)
the range of frequencies within which a
performance characteristic of a device is
above specified limits. For filters,
attenuators, and amplifiers these limits are
generally taken to be 3 dB (half-power)
below the average level.
baseband—For microwave systems, the
available frequency band that the RF
equipment is capable of transmitting.
base station—An item of fixed radio
hardware consisting of a transmitter and
receiver.
baud—Used to define the operating speed
of a printing telegraph of data system. It is
the total number of discrete conditions or
signal events per second.
baudot code—A five-unit code used for
teletypewriter signals.
beacon—A radio transmitter or lights
designed to indicate exact geographical
location or direction.
beam—A configuration of radiated energy
whose rays are sharply directional and
parallel.
beat—A regularly recurring pulsation from
the combination of two-tone or frequency
waves of different frequencies.
beat frequency—the frequency produced
when signals of two different frequencies
are combined and refracted. The beat
frequency is equal in value to the difference
between the original frequencies.
bel—A unit of relative power, named after
Alexander Graham Bell, and used to express
differences in power.
beeper—a pocket paging receiver that emits
a beeping sound upon receiving a page
specifically directed to it.
biomedical telemetry (biotelemetry)—The
technique of monitoring or measuring vital
biological parameters and transmitting data
to a receiving point at a remote location.
Biophone—Trade name of Biocom, Inc. for
portable telemetry devices.
bit—A unit of digital information
(abbreviation of “binary digit”).
boom microphone—A microphone
arranged on an arm type mechanical support
to permit better placement of the
microphone.
braid—A group of fibrous or metal
filaments or threads woven into a cylindrical
shape to form a covering over one or more
wires.
broadcast—Radio or television
transmission intended for general reception.
Business Radio Service—A subpart of the
Industrial Radio Services section of the FCC
rules.
busy indicator—An indicator provided at a
control point to indicate the in-use condition
of a circuit or channel.
C
cable—One or more insulated or
noninsulated wires used to conduct electrical
current or impulses. Grouped insulated wires
are called a multi-conductor cable.
calibrate—To determine error by
comparison with a known standard.
call, all—The alerting of all decoder
equipped units in a system by the
transmission of a single coded signal.
call, group—The alerting of subdivided
selective call groups by function, type of
vehicle, location, etc. by sending a single
coded signal.
call, individual—The alerting of a specific
coded decoder unit by sending a single
coded signal.
call answer—The initial answer of a call for
assistance whether by 9-1-1 or other
telephone method.
call sign—Federal Communications
Commission assigned identifying letters and
numbers used for identification of a radio
station, transmitter, or transmission.
call referral method—The calling party is
referred to a secondary number
call relay method—The call is answered at
the PSAP where the pertinent information is
gathered and then the interrogator relays the
information to the proper public safety
agency for their action. This can be
accomplished by radio, intercom, telephone,
etc.
call transfer method—The PSAP
interrogator determines the proper
responding agency and connects the user
to that agency which then performs the
necessary dispatching in accordance with
prearranged plans with cooperating
agencies.
call party hold—Enables the public safety
answering point to control the connection
for confirmation and tracing of a call.
capture effect—An effect occurring in FM
reception when the stronger of two signals
on the same frequency suppresses the
weaker signal.
cardioid microphone—A microphone
having a heart-shaped space response
pattern of 180° in front, and
minimum response in the rear.
carrier—A radio signal generally without
voice or other information.
carrier control timer (CCT)—A device
that limits the length of time that the
transmitter carrier is on.
carrier frequency—The frequency of an
unmodulated electromagnetic wave
produced by the transmitter.
cavity resonator—A space enclosed by a
metal conductor in which oscillating
electromagnetic energy is stored and whose
resonant frequency is determined by the
geometry of the enclosure.
cellular radio—A commercially available
mobile or portable radio telephone service.
Celsius—The metric scale of temperature in
which water freezes at zero degrees and
boils at 100°C. To convert a Celsius
temperature to Fahrenheit, multiply by 9/5
and add 32.
central medical emergency
dispatch(CMED)—See command and
control center.
central office—Sometimes called a wire
center; the smallest subdivision within the
telephone system which has relatively
permanent geographic boundaries.
change out—To replace.
channel element—A temperature
compensated crystal oscillator
channel guard—General Electric’s
trademark for continuous tone coded
squelch system (CTCSS).
channel, point-to-point—A radio channel
used for radio communications between two
definite fixed stations.
channel, radio—An assigned band of radio
frequencies of sufficient width to permit its
use for radio communication. The necessary
width of a channel depends on the type of
transmission and the tolerance for the
frequency of emission.
channel, television—A band of radio
frequencies 6 MHz wide used for television
broadcast
channelization—The assignment of circuits
to channels, and the arrangement of those
channels into groups.
charge—To replenish the electrical
potential in a battery or capacitor.
charge, fast or quick—A method of
quickly recharging batteries under controlled
conditions.
charge, trickle—The continuous charge of
a battery at a slow rate.
chart, 4/3 earth’s radius—A radio profile
chart whose horizontal lines are curved to
correspond to an earth having a radius 4/3
times larger than actual earth radius.
chassis—The framework on which parts of
a radio or other electronic circuits are
mounted.
circuit merit—A rating of overall circuit
quality. Circuit merit ‘5” is clear circuit.
Merit ‘3’ is readable with noise. Any rating
below ‘3’ is not readable and generally
unacceptable.
class of service—Service order code
designation of the combination of telephone
service features (equipment, calling area
units, dial types) to which business and
residence customers subscribe. It is
used for rating, identification, and
assignment purposes.
coaxial cable—A transmission line in which
one conductor completely surrounds the
other, the two being coaxial and separated
by a continuos solid dielectric or by
dielectric spacers.
code dialing—A method of signaling or
encoding and decoding address codes by the
use of standard telephone dial.
command and control center (central
communications center)—A system which
is responsible for establishing
communications channels and identifying
the necessary equipment and facilities to
permit immediate management and control
of an EMS patient. This operation must
provide access and availability to public
safety resources essential to the effective
and efficient EMS management of the
immediate EMS problem.
common mode rejection (CMR)—The
ability of differential amplifier to reject
unwanted signals.
communications subsystem—Comprises
those resources and arrangements for
notifying the EMS system of an emergency,
for mobilizing and dispatching resources, for
exchanging information, for remote
monitoring of vital indicators, and for the
radio transmission of treatment procedures
and directions.
communications system—a collection of
individual communication networks,
transmission system, relay stations, control
and base stations, capable of interconnection
and inter-operations that are designed to
form an integral whole. The individual
components must serve a common purpose,
be technically compatible, employ common
procedures, respond to control and operate
in unison.
comparator—A circuit which compares
tow or more signals, and selects the
strongest or best.
compression—In audio systems, reducing
the volume range of the input signal so that
the minimum output has less noise, and the
maximum output has less distortion.
compressor—A variable gain audio device
used to provide a relatively constant output
level for a wide range of varying input
levels.
cone of silence—The area directly over or
under a vertical transmitting antenna in
which little or no signal is radiated.
console—A cabinet housing electronic
circuitry normally used in controlling other
equipment such s transmitters and receivers
installed at a remote location.
consolette—(1) Motorola Communications
name for a desk top radio station (2) A
device for mounting a mobile microphone,
control head and speaker.
continuous tone controlled squelch system
(CTCSS)—A system wherein radio
receiver(s) are equipped with a tone
responsive device which allows audio
signals to appear at the receiver audio output
only when a carrier modulated with a
specific tone is received. The tone must be
continuously present for continuous audio
output. CTCSS functions are sometimes
referred to by various trade names such
as private line or PL(Motorola
Communications & Electronics), Channel
Guard or CG(General Electric Mobile
Radio) or Quiet Channel (RCA).
control console—A desk-mounted,
enclosed piece of equipment which contains
a number of controls or circuits used to
operate a radio station.
control head—A device with appropriate
controls, microphone, volume, squelch,
on/off, etc., generally mounted in a vehicle,
from which control of the radio or mobile
unit is performed.
control point—A position from which a
radio system is controlled and supervised.
control, remote—A control scheme for a
radio system where all control functions are
performed remotely via telephone lines.
continuous duty—(1) An unending
transmission (2) Operating 100% of the time
(3) EIA—full load output under the
manufacturers normal loading conditions for
the class of service for 24 hours.
control, local—A control system packaged
with the control unit mounted directly on the
base station.
coordination, frequency—The cooperative
selection and allocation of radio frequencies
such that all systems can operate with
minimum interference.
couple—To connect two circuits so that
signals are transferred from one to the other.
coverage—In a radio communications
system, the geographic area where reliable
communications exist; usually expressed in
terms of miles extending radially from a
fixed radio station.
crosstalk—The unwanted transfer of energy
from one communication circuit to another
by means of a mutual coupling.
crystal—A piece of quartz or similar
material that has been ground thin and to the
proper size to produce vibrations at the
desired frequency. Used in radio
transmission to generate, with a high degree
of accuracy, the assigned carrier frequency
of a station.
cut over—To transfer from one system to
another.
cycle—One complete reversal of an
alternating current, including a rise to the
maximum level in one direction and a return
to zero. The number of cycles occurring in
one second is the frequency of the current.
The word cycle is commonly used to
mean cycles per second (hertz).
D
dBm—Decibels referenced to one milliwatt.
Employed in communication work as a
measure of absolute power. Zero dBm
equals one milliwatt.
dBV—Decibels referenced to 1 V.
dBW—Decibels relative to 1 W (1 dBw =
30 dBm).
decibel (dB)—A unit which expresses the
level of power value relative to a reference
power value. Specifically, the level of
power, value P, relative to a reference value,
PR, in decibels is defined as dB =
10*log10(P/PR).
DC control—A remote base station control
scheme that requires metallic conductors
and currents
decoding—The conversion and recognition
by the addressed (receiving) unit of
numerical address codes that have been
transmitted through a communications
system.
dedicated telephone line—A telephone
wire pair, originating at one point, and
terminating at another point, operating in a
closed circuit. Also called private line.
defibrillator—An electrical device used to
eliminate fibrillation of the heart muscle, by
the application of high voltage impulses.
demodulation—The process of recovering
the modulating information from a
modulated signal.
deviation ratio—The ratio of the maximum
frequency deviation of the RF carrier to the
highest frequency contained in the
modulating band.
dial tone first—Allowance of a 9-1-1 or ‘0’
operator calls to be completed without the
deposit of a coin in a telephone pay station.
digital—Data represented in discrete,
discontinuous form, as contrasted with
analog data represented in continuous form.
digital dial code—A signaling technique
generally used in VHF radio systems to
bypass a receiver CTCSS system
diplexer—A device which enables the use
of two radio transmitters, operating on
different frequencies, on the same antenna
simultaneously.
direct—In terms of communications
circuits, means a dedicated instant method
of communications. A dial telephone is not
direct, a radio or a ring down line are direct.
direct dispatch method—A system where
all 9-1-1 call answering and radio
dispatching is performed by the personnel at
the public safety answering point.
direct distance dialing(DDD)—Telephone
service which permits subscribers to dial
their own long distance calls.
direct leased land lines—Dedicated or
designated point-to-point wire circuits
telephone) used in transmitting voice or data
communications. See dedicated telephone
line.
direct trunking—An arrangement where a
telephone line connection has no
intermediate points before reaching the final
destination (called) party.
directional antenna—An antenna which
radiates radio waves more effectively in
some directions than in others.
directivity—The value of the direction gain
of an antenna in the direction of its
maximum value.
dish—A type of antenna. A parabolic
reflector used in microwave systems.
dispatch point—A position from which a
radio system is used but not a supervision or
control point. Dispatch points are not
usually listed on a station radio license.
distortion—Unfaithful reproduction of
audio or video signals due to change
occurring in the wave form of the original
signal, somewhere in the course of its
transmission or reception. The lower the
percentage
of distortion, the more distortion free the
system is and the more intelligible the
message.
diversity—A method of radio transmission,
or reception, or both, which counteracts the
effects of fading by combining several
signals all bearing the same information.
doctor-interrupt—The ability of a
physician or hospital-based communicator to
interrupt the voice or telemetry transmission
from a radio in the field.
dual-tone multi-frequency (DTMF)—The
simultaneous generation of two audio tones
generally compatible to AT&T’s standard
“touch-tone” frequencies. Used for control
or signaling purposes. A method of
sending specific pairs of audio tones for
each digit, up to a total of 16.
duplex—The operation of transmitting and
receiving apparatus at one location in
conjunction with associated transmitting and
receiving apparatus at another location: the
process of transmission and reception being
simultaneous. The simultaneous
transmission and reception of information. A
duplexed piece of equipment is capable of
transmitting and receiving simultaneously.
Duplex systems generally employ different
transmitting and receiving frequencies.
duplexed operation—The operation of
associated transmitting and receiving
apparatus concurrently as in ordinary
telephones without manual switching
between talking and listening periods. For
comparison see simplex operation.
duplexed/multiplexed telemetry unit—A
radio device capable of simultaneous
transmission and reception and concurrent
transmission of both voice and EKG
information.
duplexer—A device which is used in radio
equipment to provide simultaneous transmit
and receive capabilities on a single antenna.
duplex, half—A system in which
communication may be in either direction
but only one way at a time. Transmission in
one direction at a time over a single channel.
E
E & M signaling—An arrangement by
which signaling between two points on a
radio or carrier path is accomplished. An M
lead is associated with the transmit (or
mouth) while the E lead is associated
with the receiver (or ear).
EACOM—Emergency and Administrative
Communications for hospitals. Trade name
for VHF radio system operating on standard
frequencies with a selective calling system
between stations. The system is similar to
Motorola Communications HEAR radio
system.
effective height—The true electrical height
of an antenna corresponding to a “perfect”
antenna that will produce the same field
strength. The height of its center of radiation
above the effective ground level.
effective radiated power(ERP)—The
calculated power output from an antenna
system which incorporates all the gains and
losses in the antenna system. ERP is
calculated as follows (1) convert power
output of transmitter to dB referenced to 1
W(dBw); (2) subtract all transmission line
losses including losses in equipment
between the transmitter and antenna
(filter, diplexers, circulators, duplexers, etc.)
expressed in dB; (3) add the antenna’s
power gain (expressed in dB reference to a
half-wave dimple); and (4) convert the
results into watts.
effective signal radiated—The rating basis
for licensing radio transmitters. Equal to the
square root of the effective radiated power
times the antenna height in feet aboveground
level.
EKG display console—A unit of electronic
equipment located in a hospital emergency
room, or cardiac care unit, or both, which
displays EKG and records voice and data
information received from an EMS scene by
transmission via radio or telephone path.
A demodulation display console.
electrocardiogram(ECG or EKG)—A
visual or hard copy trace of a patient’s
electrical heartbeat information.
electrode—(1) Either of the two terminals
of an electric source, such as a battery, (2) A
conducting element through which electric
current enters or leaves an electrolyte, gas,
or vacuum, (3) A conducting element,
usually metallic (such as silver/silver
chloride), with a conducting medium or
electrolyte (such as sodium chloride and
water) attached to a patient to obtain the
electrical signals of the heart.
electromagnetic radiation—Radiation
associated with a periodical varying electric
and magnetic field and is traveling at the
speed o flight, including radio waves, light
waves, X-rays, and gamma radiation.
electromagnetic wave—A wave of
electromagnetic radiation, characterized by
variations of electric and magnetic fields.
emergency call—A all that requires
immediate action.
emergency medical dispatcher (EMD)—a
trained public safety telecommunicator with
additional training and specific emergency
medical knowledge essential for the efficient
management of emergency medical
communications.
emergency medical dispatching—The
reception and management of requests for
emergency medical assistance.
emergency medical dispatch priority
reference system (EMDPRS)—A
medically approved reference system used
by a local dispatch agency to dispatch aid to
medical emergencies, which includes:
systematized caller interrogation questions,
systematized pre-arrival instructions, and
protocols matching the dispatcher'’
evaluation of injury or illness severity with
vehicle response mode and configuration
Emergency Medical Service (EMS)—The
service utilized in responding to the
perceived individual need for immediate
medical care in order to prevent loss of
life or aggravation of physiological or
psychological illness or injury.
emergency operations center (EOC)—(1)
A secure, protected facility designed and
equipped for the use of community officials
to manage response of a community in time
of emergency, (2) A communications center
designed and operated by a community or
within a geographic area for a combination
of emergency resources, such as police, fire
and EMS.
emergency resource coordination center
(ERCC)— Generally a facility that has the
resources and ability to coordinate all
emergency services (police, fire, EMS, etc.)
within a given geographic area. ERCC
works in conjunction with a public safety
answering point (PSAP) and may be in the
same facility or location.
enclosure—A housing such as a case,
cabinet, cabinet rack or console which is
designed to provide protection and support
to equipment.
encoding—The conversion of numerical
address codes, such as telephone number or
message codes, into a format of tone or on-
off pulses of audio tones for transmission
over a communications system, usually
for individual or group addressing, such as
for paging or selective calling.
exchange—A defined area, served by one or
more telephone central offices, within which
the telephone company furnishes service.
exciter—The low level stages of a
transmitter which normally consists of an
oscillator, modulator and multiplier.
extender board—A printed circuit board
that plugs into a module’s circuit connector
at one end and the module on the other to
maintain a circuit so that the module may be
conveniently tested out of an inaccessible
position.
F
facility—A communications facility is
anything used or available for use in the
furnishing of communications service.
facsimile—The process by which pictures,
images, and other fixed graphic materials
are scanned and the information converted
into electrical signals for local use or
transmission remotely to produce a likeness
of the subject copy.
fading—The variation of radio field
strength caused by a gradual change in the
transmission medium.
fade margin—The number of decibels of
attenuation which can be added to a
specified radio frequency propagation path
before the signal-to-noise ratio of the
channel falls below a specified minimum.
FCC Part 90—The section of the Federal
Communications Commissions Rules and
Regulations that affects most EMS
communications.
Federal Communications Commission
(FCC)—A Board of commissioners
appointed by the President under the
Communications Act of 1934 to formulate
Rules and Regulations and to authorize use
of radio communications. The FCC
regulates all communications in the United
States by radio or wireline, including
television, telephone, radio facsimile and
cable systems.
feedback—The act of returning a portion of
the output voltage of a circuit which
includes amplification to the input of that
circuit.
feedback, acoustic—The feeding back of
sound waves from a loudspeaker to a
microphone in the same audio system.
field strength—The strength of an electric,
magnetic or electromagnetic field.
Electromagnetic (radio) field strength is
expressed in microvolts per metre or
millivolts per metre.
fixed service—A service or radio
communication between specified fixed
points. Fixed station: (1) a radio station
which is not mobile; (2) a station which
is permanently installed; (3) a base station in
a mobile radio system.
fixed relay station—An operational fixed
station established from the automatic
retransmission of radio communications
received from either one or more fixed
stations or from a combination of fixed
and mobile stations and directed to a
specified location.
F-Layers—The upper layers of ionization in
the ionosphere. The f-1 layer is about 130
miles above the earth. The f-2 layer height
varies from about 250 miles during the day
to about 150 miles at night.
float—To operate a storage battery in
parallel with a charger and a load at such
voltage that the charger supplies the load
current and the battery supplies only
transient peaks above the normal load.
FM transmitter—A radio transmitter that
emits or radiates a frequency modulated
wave.
folded dipole—A receiving or transmitting
antenna composed of two parallel dimples,
connected at the ends. The connection to the
receiver or transmitter is made at the center
of one of the poles.
forced disconnect—The capability of the 9-
1-1 center to disconnect a 9-1-1 call to avoid
caller jamming of the incoming phone lines.
four wire operation—Telephone operation
in which the inbound audio signal is carried
on one pair of wires and the outbound signal
on another pair.
free space loss—The theoretical radiation
loss that would occur in transmission if all
variable factors were disregarded. Free
space loss depends only on the frequency
and the distance between antennas.
frequency—The number of cycles,
repetitions, or oscillations of a periodic
process completed during a unit of time. The
frequency of waves in the electromagnetic
spectrum (radio waves) is designated in
hertz (Hz), kilohertz (kHz = 1000 Hz). One
hertz is equivalent to one cycle per second.
frequency modulation (FM)—A method of
modulating a carrier-frequency signal by
causing the frequency to vary above and
below the unmodulated value in accordance
with the intelligence signal to be
transmitted. The amount of deviation in
frequency above and below the resting
frequency is at each instant proportional to
the amplitude of the intelligence signal
being transmitted. The number of complete
deviations per second above and below the
resting frequency corresponds at each
instant to the frequency of the intelligence
signal being transmitted.
frequency response—The transmission loss
or gain of a system, measured over the
useful bandwidths, compared to the loss or
gain at some reference frequency (generally
1000 Hz).
fresnel zone—The circular zone about the
direct path between a transmitter and a
receive at such a radius that the distance
from a point on this circle to the
receiving point has a path length that is
some multiple of a half wave length longer
than the direct path.
fringe area—An area or locality at such a
distance from the transmitter that the signals
received are weak.
full-duplex operation—A method of
operation of a radio system which provides
simultaneous two-way communications
between two points. In EMS radio
systems, provides for mutual interrupt
capabilities between the field technician and
the physician or medical direction at a
hospital location.
G
gain, of an antenna—The effectiveness of a
directional antenna in a particular direction,
compared against a standard (usually an
isotopic antenna). The radio of standard
antenna power to the directional antenna
power that will produce the same field
strength in the desired direction.
generator, standby power—A device
which develops electrical voltage from
mechanical energy. An a-c electrical power
source held in reserve and used to supply the
necessary a-c power when commercial
power fails.
generator, signal—A portable test
oscillator which can be adjusted to provide a
test signal at some desired frequency,
voltage, modulation, or waveform.
geographical assignment—The assignment
and use of communications channels on a
dedicated used basis within a given
geographic area.
GHz—Gigahertz (billion hertz, 1000 MHz)
gin pole—A pole which is used together
with ropes and pulleys as a derrick for lifting
heavy loads and for erecting poles or towers.
ground—A reference point. Also a
connection, intentional or accidental,
between an electrical circuit and the earth or
its equivalent.
ground plan antenna—A type of vertical
transmitting or receiving antenna used
primarily for short wavelength or high band
communications. A ground plane antenna
consists of a quarter-wave vertical element,
and four radial elements spaced 90° apart,
and mounted on the base of the vertical
element. Antennas of this type are non-
directional and have a low angle of
radiation.
ground wire—A conductor leading from
the radio equipment to an electrical
connection with the ground.
guard band—A narrow band of frequencies
provided between adjacent channels in
certain portions of the radio spectrum to
prevent interference between stations.
guy anchor—The buried weight or mass to
which the lower end of a guy wire is
attached.
H
half-duplex channel—A communication
channel providing duplex operation at one
end of the channel, but not the other.
Sometimes, the base station is operated in
the duplex mode, however, in EMS the
portable or mobile radio is often operated
in the duplex mode, and the base station at
the hospital operated simplex, to permit the
medical direction physician to interrupt
transmissions from the field technician. See
also Simplex.
half-duplex operation—Generally refers to
the ability of directing medical personnel in
EMS radio system to interrupt or ‘break in’
on radio transmissions from field personnel
to give instructions or ask questions.
Sometimes referred to as “physician
interrupt”. Requires duplexed
communications equipment in the field.
half-wave dipole antenna—A straight,
ungrounded antenna having an electrical
length equal to half the wave length of the
signal being transmitted or received.
Mounted vertically, it has a donut-shaped
pattern, circular in the horizontal plane.
ham—A term applied to an amateur radio
operator, as opposed to business or
commercial operators. A person that makes
amateur radio operation a hobby.
harmful interference—Any emission,
radiation, or induction which endangers the
functioning of a radio service or seriously
degrades,obstructs, or repeatedly interrupts a
radio communication service.
hand microphone—A microphone
designed to be held in the hand. Sometimes
called a “palm” microphone.
handset—A device similar to a telephone
handset used in place of a hand microphone.
hardcopy—A tangible printed copy of a
message such as that obtained from a
typewriter.
hardware—The screws, nuts, clamps,
anchors, connectors, etc. used in the
installation and maintenance of
communications systems.
hardwire—To wire or cable directly
between units of equipment without passing
through other media.
harmonic—An integral multiple of a
fundamental frequency. The third harmonic
of 20 Hz is 60 Hz. The fifth harmonic of 40
Hz is 200 Hz.
hash—Noise signal produced by an
electrical or mechanical source.
headphone—A device which can be placed
on the head to allow individual listening to
messages.
HEAR—Hospital Emergency
Administrative Radio— Motorola
Communications and Electronics trade name
for a VHF radio system operating on
standard frequencies with a selective calling
system between stations. The system is
similar to General Electric Mobile Radio
Department’s EACOM radio system.
helix—A single layer, spiral wound coil
usually having air or foamed polyethylene
core.
hetrodyne—(1) pertaining to the production
of difference in frequencies (beat
frequencies) by the combination
of the two frequencies, (2) to shift an
incoming radio signal to a different
frequency, often to a lower intermediate
frequency.
Hetrodyne frequency—The beat
frequency, which is the sum or difference
between two frequency signals.
hertz(Hz)—International unit of frequency
identical to and used instead of the old term
cycles. One hertz is equal to one cycle per
second.
high band—A portion of the VHF radio
frequency spectrum from 150 to 174 MHz in
which two-way radio operates.
hollerith code—A twelve-level code which
defines the relation between an
alphanumeric character and the punched
holes in an 80-column data card.
hookswitch—The device on which a
handset or microphone hangs when not in
use. The handset operates a switch, or
switches, which open the associated circuits.
hop—(1) The number of reflections from
the ionosphere encountered by the radio
wave in traveling from the transmitter to the
receiver (2) the number of radio links
required to span a given path.
hot line—Direct circuit between two or
more points for immediate use without
patching or switching. (See direct leased
land lines) The hot line can employ various
signaling configurations (ringdown, audio
amplifier, etc.)
hot standby operation—A method of
achieving reliable operation by energizing
two identical equipments fed by and to a
switchable input and output. A sensing
device causes transfer of input and output
circuits when a failure is indicated.
hum—Audio frequency interference which
is at the frequency of the power supply or its
harmonics.
humidity, relative—The ratio of the
amount of water vapor the air contains to the
maximum amount it could hold at the same
temperature and pressure, expressed in
percent.
hybrid—(1) Made up of several different
components or a mixture of technologies.
(2) A circuit required to convert 4-wire
operation to 2 wire, while maintaining
isolation of the 4-wire circuit.
I
ignition noise—Interference produced by
sparks or other ignition discharged in a
vehicle.
image—One of the two groups of sidebands
generated in the process of modulations, so
called because one is the reverse (mirror
image) of the other with respect to operating
frequency.
image frequency—In hetrodyne frequency
converters, an undesired input frequency
which can beat with the local oscillator to
produce the intermediate frequency and thus
appear in the receiver output.
image rejection—The action of a receiver
in suppressing the image frequency.
impedance—The total resistance that a
circuit offers to the flow of alternating
current. Impedance is a combination of
resistance and reactance. The ohm is used as
a unit of impedance measurement.
impedance match—The condition in which
the impedance of one component is the same
as the component to which it is connected or
attached.
impedance, characteristic—The
importance of characteristic impedance lies
in the fact that when a transmission line is
terminated, as with an antenna, in an
impedance matching its own, then all of the
energy or power flowing along the line is
radiated by the antenna. If the impedance of
the termination (antenna) is not matched to
the transmission line, a portion of the energy
will be reflected at the mismatch resulting in
a lower output from the antenna.
Improved Mobile Telephone Service
(IMTS)—A mobile radio telephone offering
of a telephone company.
impulse—A surge of electricity having a
single polarity.
indicator—A device used to inform of a
condition or change in condition.
induced—Produced as a result of exposure
to a changing electric or magnetic field.
Industrial Radio Service—An FCC-
designated radio service.
in-band signaling—The transmission of
signaling tones within the frequency band of
the channel.
insertion loss—The loss introduced when a
device or line section is interposed between
two elements of a circuit.
insulation—Any nonconductive material
used to prevent the leakage of electricity
from a conductor, such as rubber, glass,
mica, etc.
integrated circuit—A complete circuit
consisting of transistors, capacitors,
resistors, diodes, etc. which is formed on a
single semiconductor substrate.
Integrated Circuit Oscillator Module
(ICOM)—A frequency determining circuit
used in General Electric radios containing a
crystal oscillator circuit and other circuits
used to generate the oscillator frequency.
interface—A concept involving the
specification of the interconnection between
two equipments or systems. The
specification includes the type, quantity, and
function of the interconnection circuits and
the type and form of the signals to be
interchanged via these circuits.
interference—Interference in a signal
transmission path is either extraneous power
which tends to interfere with the reception
of the desired signals or the distribution of
signals which results in loss of signal or
distortion of information.
intermittent—Not continuously present;
disappearing and reappearing.
intermittent duty cycle—A duty cycle of 1
minute on 4 minutes off, or 20% per
electronic industries association (EIA).
intermodulation—The combination of two
signals beating together to form a third
unusable signal which interferes with the
reception of the desired signal. In a radio
receiver the method of expressing in dB
below the desired signal, the receiver’s
rejection of the unwanted signal to its
acceptance of correct signals.
intrinsically safe—A laboratory (UL) rating
for equipment considered approved to
operate in areas in which hazardous
concentrations of flammable gases exist.
inverter—(1) Any of several devices used
to convert direct current to alternating
current (2) a single input, single output
device which changes the polarity of
(inverts) a signal when passing it from input
to output. A negative signal at the input
produces a positive signal at the output and
vice versa. A differential EKG amplifier has
a normal and an inverting input.
ionosphere—The upper portion of the
earth’s atmosphere beginning at about 50
miles above the surface of the earth’ the
cause of radio signals being bent, and
returned to earth.
isolator—A passive RF device which
permits transmission in only one direction,
absorbing energy in the opposite direction.
J
jack—A connecting device ordinarily used
to make electrical contact with mating
contacts of a plug.
jacket—The outer covering on an insulated
wire or cable.
jamming—The deliberate radiation, re-
radiation or reflection of electromagnetic
energy with the object of impairing the use
of electronic devices, equipment or systems.
jumper—A short length of conductor used
to bridge electrical connections.
junction box—A metal or other container
into which wires or cables are led and
connected.
K
key—A push-to-operate switch used for
operating a transmitting circuit in a radio
system
key telephone equipment—An instrument
that has the capability of multiple line
terminations. Each line is accessed by
depressing an association button (key).
keypunch—A machine controlled by a
typewriter like keyboard which enables an
operator to punch holes in predescribed
places in a hollerith code.
kilo—A prefix meaning one thousand.
kbps—Thousands of bits per second.
kilohertz(kHz)—Equal to 1000 cycles per
second. Replaces the term kilocycle.
klystron—An electron tube in which the
electrons are periodically bunched by
electric fields. Used as an RF oscillator for
microwave equipment.
knockout—A metal disc punched in the
side of a metal terminal junction box or
cabinet which can be punched out to allow
entry of a cable or conduit.
L
land line—A generic term which refers to
the public-switched telephone system.
lag—The difference in phase angle
expressed in electrical degrees between the
voltage and current which produced it.
land-mobile—An abbreviation for land to
mobile communications such as between
base stations and mobile radios or from
mobile radio to mobile radio.
Land Mobile Radio Service—A mobile
radio service defined by the Federal
Communications Commission-FCC Rules
and Regulations Part 90.
LATA—Local access and transport area
boundaries for telephone companies. The
geographic area within which the local
telephone company provides local and long
distance service.
Law Enforcement Assistance
Administration (LEAA)—An
administration under the United States
Department of Justice established by the
Omnibus Crime Control and Safe Streets
Act of 1968, restructured by the Justice
Improvement Act of 1979 and abolished two
years later.
leased line—A pair of wires or a circuit,
usually leased or rented from a telephone
company, designed for exclusive use
between two fixed points for various
communication control functions.
life cycle—A test performed on a material
device to determine the length of time
before failure.
line—A transmission lien or power line. A
system of one or more wires.
linear—Describing a device in which the
signal output voltage is directly proportional
to the signal input voltage. A straight line
relationship.
line, balanced—A two-wire line which has
identical impedance from each wire.
line equalizer—A connection in series with
a telephone line that will alter the frequency
response characteristics of the line.
line, four-wire—A two-way transmission
circuit using separate paths for transmit and
receive functions.
line, loss—A transmission line, usually a
coaxial cable, which is designed to have
very high transmission loss per unit length
used in tunnels, underground or buildings
for radio communications systems.
line of sight—An unobstructed path
between two points. Radio waves at those
frequencies where signals travel in a straight
line and are not reflected by the ionosphere.
line of sight distance—The straight-line
distance from a radio station antenna to
horizon. This represents the normal
transmitting range of FM transmitting
stations.
link—The portion of a radio relay system
between adjacent radio stations.
load—(1) A device that receives power
from a transmission system (2)The amount
of electric power drawn by an electric or
electronic device.
load, dummy—A device which can
dissipate energy (into heat) without radiating
it.
loading, antenna—Insertion of reactance in
an antenna circuit to improve its
transmission characteristic in a given
frequency band.
loading, ice—The stress imposed on an
antenna or antenna structure caused by ice
forming on its members.
loading, wind—The stress imposed on an
antenna or antenna structure caused by
wind.
lobe—One of the three-dimensional petals
representing the radiation or reception
efficiency of a directional antenna.
local government radio service—A service
of radio communication defined by the FCC
essential to official activities of states,
possessions, and territories, including
counties, towns, cities, and similar
governmental subdivisions.
local service area—That area that can be
called on the telephone without incurring
multimessage units or a toll charge.
log—A list of radio stations showing
frequency, location, power, and other data.
Also a communication record for a station
showing calls made, time, date and other
data. A detailed record.
loop—(1) A short transmission line that
connects a subscriber to a switchboard (2) A
closed path in which a signal may circulate.
This path may be within a piece of
equipment, such as a repeater or carrier
terminal, or may be a complete carrier
circuit.
loop resistance—The resistance presented
to the signaling portion of the terminating
set by the wireline when the far end of the
wireline is short circuited.
loss—A decrease in power suffered by a
signal as it is transmitted from one point to
another, usually expressed in decibels.
Energy dissipated without accomplishing
useful work.
loss, free space—The theoretical
transmission loss between two radio
antennas dependent only upon distance and
frequency.
loss, path—The theoretical transmission
loss between two
radio antennas dependent only upon distance
and frequency.
loss, path—The reduction or attenuation of
signal strength that occurs between the
transmitted strength and the received signal
strength.
low band—A section of the VHF radio
frequency spectrum from 25 to 50 MHz in
which mobile radio equipment is licensed to
operate.
low loss—Describing circuits and
transmission line in which little energy is
lost from the input to the output.
lower sideband—The lower of two
frequencies or of two groups of frequencies
produced by a modulation process.
lug, spade—A connector which has an open
end to slip under a terminating screw.
M
marginal—Operating at the borderline of
permissible limits.
matrix—An array of horizontal and vertical
input or output leads with cross points at the
intersections, used as a means of switching
from any input to any output.
mean—The arithmetic middle point of a
range of values, obtained by adding the
highest and lowest values and dividing by
two.
median—The point below which there are
as many instances as there are above.
medical communications control
console—An installation of communications
control equipment, usually located at a
hospital, which provides for control of the
transmitting and receiving equipment
necessary for the medical communications.
microwave—A term applied to radio waves
in the frequency range of 1,000 MHz and
upward. Microwave radio generally
performs the same functions as telephone
cables, and may be used for radio remote
control purposes.
mobile—Term used to describe equipment
designed for vehicular installation.
mobile relay station—A fixed station
established for the automatic re-transmission
of mobile service radio communications
which originate on the transmitting
frequency of the mobile stations and which
are retransmitted on the receiving frequency
of the mobile stations.
mobile repeater station—A mobile station
in the mobile service authorized to
retransmit automatically on a mobile service
frequency communications originated by
handheld or portable units or by other
mobile or base stations directed to such
hand-carried units.
mobile service—A service of radio
communications between mobile and land
stations, or between mobile stations.
mobile station—A two-way radio station in
the mobile service intended to be used while
in motion or during halts at unspecified
points.
mobile telephone service (MTS)—
Telephone service between a fixed mobile
radio base station and several vehicles
equipped with mobile radios.
mobile transmitter—A radio transmitter
designed for installation in a vehicle, vessel,
or aircraft and normally operated while in
motion.
mobile unit—A two-way radio equipped
vehicle or person. Also sometimes the two-
way radio itself, when associated with a
vehicle or person.
modem—Contraction of modulator-
demodulator.
modular—A construction technique
incorporating the use of standard size units
for interchangeability.
modulate—To vary the amplitude (AM),
frequency (FM),
or phase of a high frequency wave or carrier
in step with amplitude variations of another
wave (the modulating wave). The carrier is
usually a sine wave while the modulating
wave is often a complex voice or EKG
signal.
modulator—The electronic circuit that
combines the modulating wave with the
carrier wave. In radio transmitters the final
audio-frequency stage which mates the
audio signal with the carrier signal. In
EKG telemetry, the circuit that combines the
amplified EKG signal with the subcarrier
(audio) signal for transmission by radio or
telephone.
multi-channel system—A radio system
which uses more than one radio channel.
Also known as a multifrequency system.
multicoupler, receiver—A device which
permits several radio receivers to use the
same antenna. Usually a broadband
amplifier with several output ports.
multi-frequency operation—Employing
radio equipment capable of operation on two
or more frequencies.
multijurisdictional system—A system
covering more than one political boundary
or agency.
multipath—The propagation phenomenon
which results in signals reaching a radio
receiving antenna by two or more paths
usually resulting in a degradation of
the original signal.
multiplex—Transmitting two or more
signals over the same medium. In EKG
telemetry equipment, the ability to transmit
electrocardiograph(EKG) signals and voice
signals concurrently over the same
transmitter.
multiplex, frequency division—A
multiplex system in which the total
transmission bandwidth is divided into
narrower bands each used for a single
separate channel.
multiplex, time division—A method of
multiplexing in which the total frequency
spectrum available is used by each channel,
but only for part of the time. A sharing of
transmission ability, first by one parameter,
then by another.
multi-tone—A method of signaling that
involves tow or more tone signals produced
simultaneously or sequentially.
mute—To silence or reduce sound level.
N
netting—The process of adjusting a
system’s transmitters and receivers to the
same operating frequencies.
net loss—The algebraic sum of the gains
and losses between two terminals of a
circuit.
network—An orderly arrangement of
stations interconnected through
communications channels in
order to form a coordinated entity.
nine-one-one(9-1-1)—A three-digit
emergency telephone number accepted and
promulgated by the telephone industry as the
nationwide emergency number.
Nxx—The first three digits of a local
telephone number that uniquely identifies
that central office switching location within
its area code number for nationwide long
distance call routing.
noise—Interference characterized by
undesirable random voltages cause by an
internal circuit defect or from some external
source. Any extraneous signal tending to
interfere with the proper and easy perception
of those signals which are intended to be
received.
noise blanker—A device used in mobile
radio applications which senses the presence
of undesired noise on the desired channel
and causes the desired signal to be
interrupted for the time period that the
undesired noise signal is present. The time
period is controlled and measured in
milliseconds so that the interruption of the
desired signal is not audible.
noise level—Volume of noise usually
expressed in decibels.
noise limiter—A circuit that cuts off the
noise peaks that are stronger than the highest
peak of the desired signal being received.
nomograph—A chart having three or more
scales across which a straightedge can be
placed to provide a graphical solution for a
particular problem. In mobile radio,
nomographs may be used to determine
frequency spread, estimated radio range,
antenna height, etc.
O
octave—The interval between two
frequencies having a ratio of two to one.
ohm—An electrical unit of resistance.
ohm’s law—The current in an electric
circuit is directly proportional to the
electromotive force in the circuit. In the
form E=I*R, where E is the electromotive
force (voltage), I is the current (amperage),
and R is the resistance of the circuit (ohms).
omnidirectional—Equally effective in all
directions.
open—A break in circuit continuity
outage—A disruption of communications
from any cause, whether planned or
accidental.
out-of-band signaling—Transmission of
signals by frequencies outside of the voice
band.
overload—A load greater than a device is
designed to handle.
P
paging—A one-way communications
service from a base station to mobile or
fixed receivers that provide signaling or
information transfer by such means as
tone, tone-voice, tactile, optical readout, etc.
pair—Two wires of a signal circuit
generally applied to telephone wherein one
wire is designated “tip” and the second wire
“ring”.
passive—A device which does not
contribute energy to the signal it passes.
passive repeater—A device intentionally
interposed in a microwave transmission path
to redirect or reflect energy.
patch—A means of connecting one system
to another. A patch may be between radio
systems, or radio to telephone, as in a
radio/phone patch.
path, signal—The route by which
intelligence is conveyed from transmitter to
receiver or through a circuit.
personal radio—A small portable radio
intended to be carried by hand or on the
person of the user.
PERT—Program Evaluation and Review
Technique. A management tool for
comparing actual with scheduled program
progress.
phase—The position at any instant which
the periodic wave occupies in its cycle of
360°
phone patch—An interconnection between
radio and telephone communications circuits
which permits direct voice interchange
between telephone lines and radio system.
pigtail—A splice made by twisting together
the bared ends of two conductors.
plug-in—Describing any device having
terminals so it can be connected by simply
pushing it into a suitable socket or
connector.
portable—An easily transportable radio.
primary power—A reliable source of
electrical power normally serving as the
principle source of energy to equipment,
such as the commercial 120 volt a-c
power main.
private automatic branch exchange-
(PBX)—A telephone switchboard with
many stations not individually identifiable to
the telephone company’s switching network
requiring an operator.
private line(PL)—Motorola’s trademarked
name for continuous tone controlled squelch
system, CTCSS.
propagation, electromagnetic—The travel
of electromagnetic waves through a
medium, or the travel of a sudden electric
disturbance along a transmission line. Also
called wave propagation.
protect—To equip with devices for
safeguarding from damage by excessive
voltages, current, or physical abuse.
public safety agency—A functional
division of a public agency which provides
fire fighting, police, ambulance, emergency
medical, or other emergency services.
public safety answering point (PSAP)—
The initial answering location of a 9-1-1 call
and other calls for assistance.
public safety telecommunicator—An
individual trained to communicate by
electronic means with persons seeking
emergency assistance and with agencies and
individuals providing such assistance.
pull box—A box with a removable cover
installed in a conduit run to facilitate pulling
wire or cable into the conduit.
pulse—A signal of short duration.
pulsed tone—A system of selective
signaling using a keyed on-off tone signal.
push-to-talk or press-to-talk(PTT)—In
radio or telephone systems, that method of
communication over a speech circuit in
which transmission occurs from only one
station at a time, the talker being required
to keep a switch operated while he is
talking. The keying button used to operate a
radiotelephone transmitter.
Q
quarter-wave antenna—An antenna
electrically equal to one-fourth of the
wavelength of the signal to be transmitted or
receive.
quartz—An element consisting of pure
silicon dioxide. The original piezoelectric
material widely used to control the
frequency of oscillators.
quartz crystal—A thin square or
rectangular slice of quartz which will vibrate
at a frequency determined by its thickness.
quiet channel—The RCA Corporation’s
trademarked name for continuous tone
controlled squelch system (CTCSS).
quieting—Reduction of system noise.
quick-call—Motorola communications
Company trademarked name for a system of
selective calling, normally using two pairs
of two tones each in sequence. Quick Call II
uses a pair of sequential tones similar to
General Electric’s Type 99 tone system.
R
rack mounting—A method of mounting
equipment in which metal panels supporting
the equipment are attached to pre-drilled
steel channel rails or racks. The dimensions
of the panels, the spacing of the rails and the
size of the mounting screws are
standardized.
rack unit—In mobile radio generally a rack
mounting 19 in. between rails and a height
of 1.75 in. per unit.
radio—The transmission and reception of
signals by means of electromagnetic waves
without a connecting wire.
radio-frequency power—The power
associated with any signal consisting of
electromagnetic radiation which is used for
telecommunications.
radio interference—Undesired disturbance
of radio reception. Man-made interference is
generated by electric devices, with the
resulting interference signals either being
radiated through space as electromagnetic
waves or traveling over power lines or other
conducting media. Radio interference is also
due to natural sources such as atmospheric
phenomena, such as lightning. Radio
transmitters themselves may additionally
interfere with each other.
radio network—A number of radio
stations, fixed and mobile, in a given
geographical area which are jointly
administered or which communicate with
each other by sharing the same radio
channel or channels.
radio common carrier (RCC) —An
enterprise that is licensed by the FCC and
the Public Utilities Commission to provide
radio communications service to the public.
radio receiver—An instrument which
amplifies radio frequency signals, separates
the intelligence signals from the rf carrier,
amplifies the intelligence signal
additionally, and converts the intelligence
signal to its original form.
radio relay system (radio relay) —A
point-to-point radio transmission system in
which the signals are received and
retransmitted by one or more intermediate
radio stations.
radio transmitter—A radio-frequency
power source which generates radio waves
for transmission through space.
radome—A dome shaped cover for a
parabolic antenna which protects the
antenna from the elements and their
attenuating effects.
range—Distance over which a radio signal
can be transmitted for effective reception or
the distance at which a usable signal can be
received.
receiver—An electronic device used to
detect and amplify transmitted radio signals.
receiver, paging—A small, light, pocket
sized receiver used for alerting individuals
when they are away from their normal
communication instruments.
referral methods—The calling party to a
public safety answering point is referred to a
secondary telephone number.
refraction—The change of direction
experienced by a wave of any form of
radiated energy when passing from one
medium to another having a different
dielectric constant or index of refraction.
regional EMS system—An emergency
medical service area (trade, catchment,
market, patient flow, geographic or
governmental) that provides essentially all
of the definitive emergency medical care for
all emergencies and for the most critically ill
and injured patients within the area.
relay—Transmission forwarded through an
intermediate station.
relay station—Radio stations that
rebroadcast signals the instant they are
received, so that the signal can be passed on
to another station outside the range of the
originating transmitter.
reliability—The ability of an item to
perform a required function under stated
conditions for a stated period of time.
remote base station—A base station
located away from the operating console, to
take advantage of improved coverage
offered by a better geographical location.
remote control—The operation of a device
from a distance either electrically or by
radio waves.
remote control equipment—The apparatus
used for performing monitoring, controlling,
supervisory control, or a combination of
these functions at a distance by electrical
means.
repeater—A combination of apparatus for
receiving either one-way or two-way
communication signals and delivering
corresponding signals which are either
amplified or reshaped or both.
repeater station—An operational fixed
station established for the automatic re-
transmission of radio communications
received from any station in the mobile
service.
repeater station, re-modulating—A
microwave repeater station in which the
signal is demodulated to the original
baseband frequencies and re-injected onto
the modulator for transmission to the distant
station.
resource management center—A center
responsible for the allocation of those
resources essential to the most effective and
efficient resolution, or management or both,
of the immediate problem. In most
communities these resources include police,
fire and emergency medical services. The
resource management center is most
effective when its responsibilities
encompass the whole of public safety
response.
ringback—In a public safety answering
center, permits the answering point to ring
the hung-up telephone on a held circuit. The
feature is useful when calling a party has
failed to provide all necessary information to
the answering point before hanging up.
ringdown—A type of signaling employed
in manual operation telephone (as compared
to dial) which utilizes a continuos or pulsing
a-c signal transmitted over the line.
S
schematic diagram—A diagram or drawing
which shows electrical connections of a
radio or other electrical device by means of
symbols which are used to represent the
components.
search lock monitor—A receiving channel
scanning scheme which lock the receiver on
the first channel received.
selective call—A system for alerting
individual or groups of stations by means of
coded signals.
selectivity—The ability to select one
particular signal from other signals at nearby
frequencies. This specification is important
in urban areas where radio spectrum
congestion exists. The more negative the
dB rating, the better the specification.
selective routing—A routing of telephone
call to terminate at a PSAP determined by
the location of the calling telephone. This is
accomplished by using a computer to
process the calling telephone number.
sensitivity—The characteristic of a radio
receiver which determines the minimum
input signal strength required for a given
signal output. In FM, sensitivity is the signal
level required to produce e a given ratio
of signal to noise. The more sensitive a
receiver is, the weaker the signal it can
receive.
service channel—In a microwave system, a
voice channel fused for maintenance and
fault location. Also called order wire.
service life—The life expectancy of
equipment under normal conditions of use.
side tone—The signal that reaches a
telephone receiver from the transmitter of
the same set by way of a local path within
the set.
Signal—The form of a radio wave in
relation to the frequency serving to convey
intelligence in communication.
signal-to-noise ratio—The ratio of the
intensity of the desired signal to that of the
undesired noise signal, usually expressed in
decibels.
signal strength—A measure of the field
intensity caused by a radio transmitter at a
particular location within its operating
range. Usually expressed as microvolts, or
millivolts of signal.
simplex—1) —single frequency operation
whereby all base stations and mobiles
operate on one common frequency, (2)
operation on two different frequencies in a
system that can communicate in two
directions, but not simultaneously, such as
when a base station and a mobile radio
operate on reversed pairs of frequencies
without duplexing.
simplex channel—a communication
channel providing transmission in one
direction only at any given time. For
comparison see duplex channel.
simplex operation—A method of radio
operation in which communication between
two stations takes place in only one
direction at a time. This includes ordinary
transmit-receive operation, press-to-talk
operation, voice-operated transmit, and other
forms of manual or automatic switching
from transmit to receive. Also called
simplex.
SINAD —The ratio of signal plus noise plus
distortion to the noise plus distortion;
expressed in decibels. An EIA standard
method of measuring receiver sensitivity.
Basically a measure of RF signal strength
that will result in a readable signal.
siren—An acoustical or electromechanical
device used as a warning signal on
emergency vehicles.
solid state—Denoting the use of
semiconductors instead of
vacuum tubes or relays.
Special Emergency Radio Service (SERS)
—That portion of radio communications
frequency resources authorized by the FCC
for use in the alleviation of emergency
situations endangering life or property.
See FCC Part 90.
spectrum—A continuous range of
frequencies arranged in order of wavelength
or frequency within which
waves have some common characteristics,
such as audio spectrum, radio spectrum, etc.
The entire range of electromagnetic
radiation extending from the longest known
radio waves to the shortest known cosmic
rays.
spurious response—The response of a
radio receiver to an undesired frequency.
squelch—A circuit function that acts to
suppress the audio output of a receiver when
noise power exceeding a predetermined
level is present.
squelch, carrier—A squelch system that
responds to the presence of an RF carrier
signal.
squelch circuit—A circuit that reduces or
lowers the noise that would otherwise be
heard in a radio receiver between
transmissions.
stability, frequency—The ability of a radio
transmitter to maintain any predetermined
frequency, such as its assigned frequency.
Measured in percent of the carrier. The
lower the percentage the better the stability.
standing wave ratio (SWR) —A measure
of the amount of lost transmitting power due
to impedance differences between the
transmission line and the antenna. The ratio
of reflected to incident waves that
exists at some particular point on a
transmission line.
statewide EMS system—A network of
EMS systems, integrated and coordinated at
the state level.
strip chart recorder—An
electromechanical device used to make
paperchart recordings of EKG information.
Usually it uses a heat-sensitive paper and a
heated stylus.
subcarrier—A frequency sensitive device
used to generate a modulated wave which in
turn is applied as a modulating wave to
modulate another carrier. For EMS
telemetry the subcarrier frequency is 1400
Hz.
supergroup—In microwave systems groups
of 60 channels each, occupying a particular
range of frequencies.
switched network—A complex of
diversified channels and equipment that
automatically routes communications
between the calling and called
person or data equipment. The public
telephone system.
synchronization—The process of making
the carrier at the receiving end of a line or
system match the frequency of the carrier at
the transmitting end.
synthesizer, frequency—A highly precise
crystal oscillator with frequency dividers
used to provide the precise radio frequency.
A typical synthesizer can be set to small
frequency increments and have an accurate
output at the desired output frequency.
system—A combination of two or more
stations in such a way as to provide
communications.
T
tandem trunking—An arrangement where
a telephone-line connection has one or more
intermediate points that are required or
permitted usually on a controlled dial pulse
basis before reaching the final destination
(called) party.
tariff—A document filed by a
communications company with Public
Utilities Commission which lists the
services offered the public and schedule of
rates and charges.
tarnish—A discoloration or stain on the
surface of metal caused by exposure to
chemicals or the atmosphere. To dull or
destroy the luster of metal.
tee—A three-way connection in the shape of
the letter t.
telecommunications—All forms of
electrical transmission of intelligence
including: telegraph, telephone, radio, and
television. Pertaining to the art and science
of communication by these methods.
telemetry—The sensing and measuring of
information at some remote location and
transmitting the data to a convenient
location to be read and recorded.
telpak—An acronym for “telephone
package”, a schedule of bulk discount rates
for multiple private line telephone services
such as AT&T long-lines series 500 tariff
offering.
telephone line—A telephone lien from a
telephone company central office that is
connected to key or non-key telephone
equipment.
teletypewriter—An electromechanical
device, similar to a typewriter, such that
messages typed on the keyboard of the
transmitter unit are converted into
electrical signals, which when conveyed to
the receiver unit, are printed on paper.
ten signals—A series of coded messages
designed to reduce air transmission time and
confusion in busy mobile radio systems.
thermal noise—Very small noise voltages
that are present in all conductors, caused by
the thermal agitation of charged particles
within the conductor.
third harmonic—A frequency wave having
three times the fundamental frequency
value.
threshold—In an FM receiver, the point at
which the peaks of the incoming RF signal
exactly equal the peaks of the internally
generated thermal noise power or the point
above which increasing the input
signal strength provides only a dB for dB
improvement in the output signal-to-noise
ration.
tip—The ball-shaped contact on the cord
(tip) of a plug. One of a pair of telephone
wires (the other of which is called the ring).
tone—An audio or carrier of controlled
amplitude and frequency used in a selective
signaling system or for equipment control
purposes.
tone code—A specified character of
transmitted tone signals required to effect a
particular selection or function.
tone coded squelch—A system whereby a
superimposed tone is transmitted with the
radio carrier to protect against nuisance type
interference.
tone, Type 90—General Electric’s name for
a system of single tone signaling. The tones
are generally between 1000 and 2400 Hz in
two bands.
tone, Type 99—General Electric’s name for
its two-tone sequential selective signaling
system. Sometimes called Sel-Call. The
tones are generally between 520 and 953 Hz.
topographic map—An accurately scaled
map having contour lines which show the
elevation above sea level. Used in preparing
profiles of radio propagation paths.
touch pad—A method of signaling or
encoding and decoding address codes by the
use of a simple numerical push-button
keyboard.
Touchtone—A Bell System trademark used
to describe their method of signaling and use
of dual tone multifrequency (DTMF) tones.
tower, antenna—A tall antenna support
structure used to support one or more
antennas or when an antenna must be
mounted high above the ground or other
support formation such as a building.
traffic—Used for messages handling by a
radio communications system.
transceiver—The combination of radio
transmitting and receiving equipment in a
common housing, usually for portable or
mobile use, and employing common
circuit components for both transmitting and
receiving.
transformer—An electrical device for
voltage current transformation, or
impedance matching or both.
transfer method—The PSAP interrogator
determines the proper responding agency
and connects the user to that agency. To
perform the necessary dispatching
in accordance with prearranged plans with
cooperating agencies.
transient—A rapid, sometimes violent,
fluctuation of voltage or current in a circuit
usually of short duration caused by
switching or changes in load.
transmitter—Apparatus for the production
and modulation of radio frequency energy
for the purpose of radio communication.
transmission line—A waveguide, coaxial
line, or other system of conductors used to
transfer signal energy efficiently from one
location to another. In communications
systems, the coaxial line between the base
station and the antenna.
trunk—A circuit used for connecting a
subscriber in a central office to all other
services in/out of the switching equipment.
trunk line—A telephone line that
terminates at a switchboard rather than a
telephone.
TSPS—An electronic operating position
system whereby operator-handled traffic is
routed to its final destination via a central
switching machine.
turret—A section of communications
control console, containing switches,
controls, meters, etc.
two-way radio—A radio that is able to
transmit and to receive.
two-wire operation—Uses a single pair
(two wires) for both transmitting and
receiving.
U
Ultra High Frequency (UHF)—
Frequencies between 300 and 3000 MHz.
ultrasonic—Describing frequencies higher
than those which are audible. Generally
above 20000 Hz.
unbalanced line—A transmission line in
which the voltages on the two conductors
are unequal.
Underwriters Laboratories, Inc.—A
laboratory sponsored by the National board
of Fire Underwriters which examines and
tests devices, material and equipment
whose action may affect casualty, fire, and
life hazard.
unmodulated—Without modulation; the RF
carrier signal alone as it exists during pauses
in conversations.
upper sideband—The higher of two
frequencies or groups of frequencies
produced by a modulation process.
utility—A power, gas, or water service
available to the public.
V
Van Allen belts—Radiation belts that
surround the earth, consisting of electrons
and protons at high energy levels.
varactor—A semiconductor diode used as a
variable capacitor. Used as a harmonic
generator, frequency multiplier, and
amplifier.
vehicular repeater station—A mobile
station in the mobile services authorized to
retransmit automatically on a mobile service
frequency, communications originated by
hand carried portable units or by other
mobile or base stations directed to such
hand-carried units.
Versatone—General Electric company
trade name for a solid state tuned tone
determining element.
vertical antenna—A vertical steel tower,
rod or shaft used as an antenna.
Very High Frequency (VHF)—Frequency
between 30 and 300 MHz.
Vibrasponder—Motorola Communications
company trade name for a tone determining
vibrating reed element.
voice grade—A communications circuit
which is nominally 300 to 3000 Hz.
voltage standing wave ratio (VSWR)—
The ratio of the
maximum voltage to the minimum voltage
along a transmission line. It is the measure
of the mismatch between the load and the
line.
volume control—A potentiometer voltage
divider used to
adjust the loudness of an audio circuit.
volume unit (VU)—A measure of the
magnitude of sound
from an electrical wave. Measured in
decibels.
voting—Automatic selection of remote
radio receiver. Al incoming signals are
compared for signal strength and the first
signal found that meets or exceeds a
preset level is selected and sent to the audio
amplifier.
W
watt—The unit of power.
wattmeter—A meter to indicate the rate at
which electrical energy is being used or
produced.
wave—A propagated periodic disturbance
such as a radio, light or sound wave.
waveguide—A transmission line
comprising a hollow conducting tube within
which electromagnetic waves may be
propagated. Generally used in microwave
communications systems.
wavelength—The distance measured along
the direction of propagation between tow
points that are in phase on adjacent waves.
A wavelength is the distance traveled by a
wave in the time of one cycle.
Electromagnetic waves included both light
and radio waves and travel in space at
approximately 300,000,000 m/s. To
determine the exact length of a wave, divide
300,000,000 m by the frequency in hertz.
wave, radio—An electro-magnetic wave
which travels through space at the speed of
light.
wave, refracted—A radio wave that is bent
(refracted) as it travels into a second
medium of propagation, such as from the
atmosphere to the ionized layers of the
stratosphere.
weatherproof—So constructed or protected
that exposure to the weather elements will
not prevent proper operation.
weathertight—So constructed that exposure
to a driven rain will not result in the
entrance of water.
wire—A single metallic conductor.
ADDENDUM
Interoperability Channel Naming
Names for Channels Coordinated/Managed by CalSIEC
April 4, 2008 - Subscriber Programming Shown
.5 kHz) only with original FCC name shown
N = 12.5 kHz bandwidth MW = 20 kHz bandwidth W = 25 kHz
e
banding/Narrowbanding (Legacy Names)
Post-Rebanding/Narrowbanding
Rx
FREQ Rx CTCSS
Tx
FREQ Tx CTCSS
Bandwidth
NPSTC Name
Short Name
(6 char)
Rx
FREQ Rx CTCSS
Tx
FREQ T
x
VHF LOW BAND
VHF LOW BAND
39.4600 156.7 45.8600 156.7 W LLAW1 LLAW1 39.4600 156.7 45.8600
1
39.4600 156.7 Simplex 156.7 W LLAW1D LLAW1D 39.4600 156.7 Simplex
1
39.4800 is used by various agencies in California LFIRE2 (pend) LFIRE2 39.4800 156.7 Simplex
1
u
t 45.8600 156.7 Simplex 156.7 W LLAW3D LLAW3D 45.8600 156.7 Simplex
1
45.8800 156.7 Simplex 156.7 W LFIRE4 LFIRE4 45.8800 156.7 Simplex
1
VHF HIGH BAND
VHF HIGH BAND
155.7525 none Simplex none N
VCALL10 VCAL10 155.7525 156.7 Simplex
1
151.1375 none Simplex none N
VTAC11 VTAC11 151.1375 156.7 Simplex
1
154.4525 none Simplex none N
VTAC12 VTAC12 154.4525 156.7 Simplex
1
158.7375 none Simplex none N
VTAC13 VTAC13 158.7375 156.7 Simplex
1
159.4725 none Simplex none N
VTAC14 VTAC14 159.4725 156.7 Simplex
1
VTAC17 VTAC17 161.8500 156.7 157.2500
1
VTAC17D TAC17D 161.8500 156.7 Simplex
1
VTAC18 VTAC18 161.8250 156.7 157.2250
1
VTAC18D TAC18D 161.8250 156.7 Simplex
1
154.2800 none Simplex none W VFIRE21 VFRE21 154.2800 156.7 Simplex
1
154.2650 none Simplex none W VFIRE22 VFRE22 154.2650 156.7 Simplex
1
154.2950 none Simplex none W VFIRE23 VFRE23 154.2950 156.7 Simplex
1
VFIRE24 VFRE24 154.2725 156.7 Simplex
1
VFIRE25 VFRE25 154.2875 156.7 Simplex
1
VFIRE26 VFRE26 154.3025 156.7 Simplex
1
VMED28 VMED28 155.3400 156.7 Simplex
1
VMED29 VMED29 155.3475 156.7 Simplex
1
155.4750 none Simplex none W
VLAW31 VLAW31 155.4750 156.7 Simplex
1
VLAW32 VLAW32 155.4825 156.7 Simplex
1
Rx
FREQ Rx CTCSS
Tx
FREQ Tx CTCSS
Bandwidth
NPSTC Name
Short Name
(6 char)
Rx
FREQ Rx CTCSS
Tx
FREQ T
x
154.9200 none Simplex Varies W
CALAW1 CALAW1 154.9200 none Simplex
1
154.9350 none Simplex Varies W
CALAW2 CALAW2 154.9350 none Simplex
1
156.0750 none Simplex none W
CALCORD CACORD 156.0750 none Simplex
N
UHF
UHF
453.2125 none 458.2125 none N
UCALL40 UCAL40 453.2125 none 458.2125
1
453.2125 none Simplex none N
UCALL40D CAL40D 453.2125 none Simplex
1
453.4625 none 458.4625 none N
UTAC41 UTAC41 453.4625 none 458.4625
1
453.4625 none Simplex none N
UTAC41D TAC41D 453.4625 none Simplex
1
453.7125 none 458.7125 none N
UTAC42 UTAC42 453.7125 none 458.7125
1
453.7125 none Simplex none N
UTAC42D TAC42D 453.7125 none Simplex
1
453.8625 none 458.8625 none N
UTAC43 UTAC43 453.8625 none 458.8625
1
453.8625 none Simplex none N
UTAC43D TAC43D 453.8625 none Simplex
1
460.0250 Varies 465.0250 Varies W
CALAW4 CALAW4 460.0250 156.7 465.0250
V
460.0250 Varies Simplex Varies W
CALAW4D CLAW4D 460.0250 156.7 Simplex
V
484.2125 167.9 487.2125 146.2 W
SCMA C SCMA C 484.2125 167.9 487.2125
1
484.2125 167.9 487.2125 167.9 W
SCMA E SCMA E 484.2125 167.9 487.2125
1
484.2125 167.9 487.2125 156.7 W
SCMA N SCMA N 484.2125 167.9 487.2125
1
484.2125 167.9 487.2125 173.8 W
SCMA W SCMA W 484.2125 167.9 487.2125
1
484.2125 167.9 Simplex 167.9 W
SCMA D SCMA D 484.2125 167.9 Simplex
1
484.2375 none Simplex 156.7 W
CALAW5D CLAW5D 484.2375 156.7 Simplex
1
487.2375 none Simplex 156.7 W
FDUMA FDUMA 487.2375 156.7 Simplex
1
800 MHz
800 MHz
866.0125 156.7 821.0125 156.7 MW
8CALL90 CAL90 851.0125 156.7 806.0125
1
866.0125 156.7 Simplex 156.7 MW
8CALL90D CAL90D 851.0125 156.7 Simplex
1
866.5125 156.7 821.5125 156.7 MW
8TAC91 TAC91 851.5125 156.7 806.5125
1
866.5125 156.7 Simplex 156.7 MW
8TAC91D TAC91D 851.5125 156.7 Simplex
1
867.0125 156.7 822.0125 156.7 MW
8TAC92 TAC92 852.0125 156.7 807.0125
1
867.0125 156.7 Simplex 156.7 MW
8TAC92D TAC92D 852.0125 156.7 Simplex
1
867.5125 156.7 822.5125 156.7 MW
8TAC93 TAC93 852.5125 156.7 807.5125
1
867.5125 156.7 Simplex 156.7 MW
8TAC93D TAC93D 852.5125 156.7 Simplex
1
868.0125 156.7 823.0125 156.7 MW
8TAC94 TAC94 853.0125 156.7 808.0125
1
868.0125 156.7 Simplex 156.7 MW
8TAC94D TAC94D 853.0125 156.7 Simplex
1
868.5125 none 823.5125 156.7 MW
CALAW8 CALAW8 853.5125 156.7 808.5125
1
868.5125 none Simplex 156.7 MW
CALAW8D CLAW8D 853.5125 156.7 Simplex
1
Rx
FREQ Rx CTCSS
Tx
FREQ Tx CTCSS
Bandwidth
NPSTC Name Short Name (6 char)
Rx
FREQ Rx CTCSS
Tx
FREQ T
x
866.2000 none 821.2000 156.7 MW
CALAW9 CALAW9 851.2000 156.7 806.2000
1
866.2000 none Simplex 156.7 MW
CALAW9D CLAW9D 851.2000 156.7 Simplex
1
868.9875 156.7 823.9875 156.7 MW
CAFIRE1 CFIRE1 853.9875 156.7 808.9875
1
868.9875 156.7 Simplex 156.7 MW
CAFIRE1D CFRE1D 853.9875 156.7 Simplex
1
866.9125 156.7 821.9125 156.7 MW
CAFIRE2 CFIRE2 851.9125 156.7 806.9125
1
866.9125 156.7 Simplex 156.7 MW
CAFIRE2D CFRE2D 851.9125 156.7 Simplex
1
O
nly: Reno VHF Public Coast Service Area #34, including California counties of Alpine, Inyo, Lassen, Mono, Plumas and Sierra.
O
nly: Southern California UHF TV-Band sharing area (primarily LA County).
O
nly: NPSPAC Region 6 (48 Northern California counties).
