911 OperTions Flashcards
FCC
Federal Communications Commission
Radio Waves
Fundamentally electromagnetic waves that travel through the atmosphere.
VLF
Very-low frequency
10 to 30 kHz
LF
Low Frequencies
30 to 300 kHz
MF
Medium frequencies
300 to 3000 kHz
HF
High frequencies
3 to 30 MHz
VHF
Very high frequencies
30 to 300 MHz
UHF
Ultra high frequencies
300 to 3000 MHz
Traditionally do not carry as far as lower frequencies but do penetrate structures better.
Generally can not communicate at distances greater than 25 miles.
SHF
Super high frequencies
3 to 30 GHz
EHF
Extremely high frequencies
30 to 300 GHz
Trunked Radio
A method used to conserve radio spectrum.
In a trunked radio environment, all users share the same radio frequencies.
The channel switching is controlled by the software.
Conventional Radio
The channel switching is manually controlled by the user
Simplex Radio System
A basic radio system that transmits and receives on the same frequency.
Repeater System
Allows portable and mobile users to hear other users a great distance away.
Talk Around
Most portable or mobile equipment can be programmed with a simplex channel that uses the base stations transmit frequency.
Allowing the user to communicate with others without using the repeater.
The radio can only talk to those in a very limited area due to power, antenna, etc.
Satellite Receiver
Like repeater stations, satellite receivers are placed strategically throughout the required coverage are.
Simulcast System
Transmits the message over more than one transmitter on the same frequency.
Analog System
Uses the voices vibrations to send the voice to the transmitter.
Digital system
The voice is converted to a digital signal using a voice coder or “vocoder”.
P25
Primary objective is to enhance public safety voice communications interoperability through use of and open radio frequency interface subsystem to facilitate the ability to communicate between systems and equipment from different manufacturers.
GPS
Global Positioning System
The system relies on 24 satellites orbiting at over approximately 12600 miles out to serve as reference points for ground receivers.
DGPS
Differential Global Positioning System.
Relies on a calculation from a second terrestrial receiver at a known fixed location to the satellite and then compares it to the first calculation to determine the error in the signal.
AGPS
Assisted Global Positioning System
A-GPS is the handset-based location determination method used in wireless networks today to acquire the location of a 911 caller.
U-TDOA
Uplink Time Difference of Arrival
The predominant network based location technology used for wireless 911 call.
U-TDOA determines location based on the time it takes a signal to travel from a mobile phone to each of the sensitive receivers called LMU’s.
LMU’s
Location measurement units
Local Exchange
Refers to the service area provided by an end office.
Exchange area
Refers to the geographic area in which charges and services are uniform.
Local loop
Refers to the wires that run from the subscribers PBX, telephone, or key telephone system back to the serving central office.
Switching
Switching is the process of connecting the calling party to the called party without the use of dedicated transport facilities.
Central Office or CO
Usually refers to a local switching system that connects lines (from subscribers) and trunks and sometimes refers to a telecommunications service provider building in which switching system and telephone equipment are installed.
A central office is where the subscribers lines are joined to the telecommunications service provider switching equipment for the purpose of connecting to other subscribers locally and over long distance.
End Office or Class 5 Office
A switching system within a local access and transport area or market area where customer lines are terminated for purposes of interconnection to each other and to trunks.
Access Tandem
A switching system that provides traffic concentration and distributes calls between end offices or to an inter exchange carrier.
Facility or facilities
Is an all encompassing term used by telephone companies that can apply to any one of the elements of physical telephone plant that is required to provide service.
VoIP
Voice over internet protocol
Is an internet protocol telephony term for a set of capabilities used to manage the delivery of voice information over the internet.
VSP
VoIP service provider
CMRS
Commercial mobile radio services.
Also known as wireless service provider, is an FCC term for any carrier or licensed whose wireless network is connected to the PSTN.
