BASICS TERMINOLOGY Flashcards
VHF radio spectrum
Radio frequency range from 30 MHz to 299 MHz. The sub-bands most commonly used by fire are: VHF-FM Lo band: Frequency Modulation 30 MHz - 80 MHz, of which fire frequencies are between 30 MHz and 50 MHz.
What is VHF best suited for?
long distances and outdoor use, Wild land
What is UHF?
UHF, abbreviation of ultrahigh frequency, conventionally defined portion of the electromagnetic spectrum, encompassing radiations having a wavelength between 0.1 and 1 m and a frequency between 3,000 and 300 megahertz. UHF signals are used extensively in televison broadcasting.
What is UHF best suited for?
UHF operates on a higher frequency and is ideal for wireless communications that need to penetrate through buildings, walls, concrete, et.c
What is the Line of sight in RF?
Is the direct propagation in radio waves between antennas that are visible to each other
What is radio propagation?
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another, or into various parts of the atmosphere. … Line-of-sight propagation means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna.
What is the maximum distance between line of sight propagations?
25 miles
What is the radio horizon?
The curvature of the earth
Frequency overlapping
This means that if two radios are using the same frequency then the radio waves interrupt each other, and the transmissions overlap. This will most likely happen when they are in the range of each other or are in the same coverage area.
What is the Difference Between UHF and VHF?
The main difference between UHF and VHF is range. UHF two-way radios have a range that is wider than VHF. This means that UHF frequencies have smaller waves that produce a greater range. They are more likely to pass barriers like rocks and trees easier.
Another difference between UHF and VHF is their battery life. UHF uses a lot of its battery due to the higher frequency. The last difference between the two radios is that UHF does come at a higher cost than VHF.
What are the 3 basic methods to two-way radio communications?
Simplex, duplex, trunking
Simplex communication
is a communication channel that sends information in one direction only.
Limited in number of users on channel
AKA “direct” or “talk around”
Duplex communication
operation means that a radio station transmits on one frequency and receives on a different frequency
Can still have user overload
Trunked
is a single channel of communication that allows multiple entities at one end to correspond with the correct entity at the other end. It is a “link” that carries many signals at the same time, creating more efficient network access between two nodes.
What are the communications assets?
- cache radio and communications vehicles
- Mobile repeaters and gateways
- Trained personnel for communications planning
Cache radios
Have multiple radios integrated into a single system
(radio systems in cars)
Used for emergency events to reduce user overload
Gateways
Are a tool to patch multiple radio frequencies together in same and different bands. A Radio Gateway allows one radio to talk to another radio that is many many miles away through the power of ROIP (Radio Over IP). ROIP - similar to VOIP - sends the radio signal through the internet.
Can be based or mobile
Mobile Repeaters
A cellular repeater is a type of bi-directional amplifier used to improve cell phone reception. A cellular repeater system commonly consists of a donor antenna that receives and transmits signal from nearby cell towers, coaxial cables, a signal amplifier, and an indoor rebroadcast antenna
Mobile command vehicles include:
Gateway and cache radio systems (fire trucks, ambulances, police cars)
Communications unit (COML)
The Communications Unit Leader (COML) is responsible for designing, installing, and maintaining communications equipment on wildland fire incidents. The COML also provides data, telephone, and radio communications support for incident personnel.
What are the four radio system elements?
#1. Capacity: Capacity relates to the capability of the radio system to sustain a given number of conversations at the same time. #2. Frequency #3. Coverage #4. Type
Conventional Radio Systems
radio systems that have dedicated frequencies and channels assigned to individual
groups. A simplex configuration utilizes the same frequency to transmit and receive. A duplex
configuration utilizes two frequencies; one to transmit and one to receive.
800 MHz Mutual Aid Conventional Channels
are configured for both a conventional duplex repeater
radio system with simplex channels. This system is
comprised of one calling channel and 4 tactical
channels repeated and 4 simplex channels
Subscribers units
devices like portable radios, mobile radios, desktop, etc.
UMLEC
Used as a command and control
Infrastructure radio:
Base station radios and antennas
What are the three basic methods to two way radio communications?
Simplex, duplex, and trunking
What is Simplex Communications?
Simplex communication is a communication channel that sends information in one direction only.[
Limited number of users can be on this channel
AKA “direct” or “talk around”
What are some examples of simplex communications?
Examples of simplex include radio broadcasting, television broadcasting, computer to printer communication, and keyboard to computer connections.
What is Duplex Communications?
A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions
What are examples of Duplex Communications?
An example of a half-duplex device is a walkie-talkie, a two-way radio that has a push-to-talk button
What is Trunking in regard to communications?
A network that handles multiple signals simultaneously. The data transmitted through trunking can be audio, video, controlling signals or images.
Trunks typically connect switching centers in a communications system.
What are examples of trunking in regard to communications?
Trunking is used by many government entities to provide two-way communication for fire departments, police and other municipal services, who all share spectrum allocated to a city, county, or other entity.
What is radio frequency?
(RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency[1] range from around 20 kHz to around 300 GHz.
Hertz
Herz is a measure of frequency per unit of time, or the number of cycles per second. The most common uses for hertz are to describe radio and audio frequencies.
What is frequency?
The number of electromagnetic wave signals that pass a given point per unit time
What is Wavelength?
The distance in which the fields of an electromagnetic wave repeats themselves
Microwave frequency
A microwave is an electromagnetic wave with a relatively long wavelength and low frequency. Microwaves are often classified as radio waves, but they have higher frequencies than other radio waves. refer to 30-300 GHZ
Millimeter wave frequency
refers to 30-300 GHZ
Kilohertz (kHz)
is defined as thousands of cycles per second.
Megahertz (MHz)
MHz is defined as millions of cycles per second - 1000 x more than kilo.
Gigahertz (GHz)
GHz is defined as billions of cycles per second - 1000 x more than mega, or 1,000,000,000 cycles per second - Microwave towers, UHF and EHF transmission - operate in the 1GHz to 100GHz range.
Terahertz (THz)
THz is defined as trillions of cycles per second- Wavelengths at frequencies still higher than EHF - GHz are referred to as Terahertz radiation, but are more familiarly understood as infrared light.
Frequency Band
sometimes called a frequency band - is a specific range of frequencies in the radio frequency (RF) spectrum, which is divided among ranges from very low frequencies (vlf) to extremely high frequencies (ehf). Each band has a defined upper and lower frequency limit.
What are examples of uses in regard to Radio Spectrum bands?
- AM/FM Radio
- Broadcasting networks
- wireless data
- mobile phones
- Microwaves
- television
- radar
- sound waves
Power
is related to the energy of the waves. The stronger the power, the further the wave can travel or how deep in can penetrate.
Bandwidth
The width that is being covered by signal or system
Amplitude
Power level of an RF Wave
Period
Distance between two identical points on an RF wave
Analog signal
Analog signal is a continuous signal in which one time-varying quantity represents another time-based variable. These kind of signals works with physical values and natural phenomena such as earthquake, frequency, volcano, speed of wind, weight, lighting, etc.
digital signal
A digital signal is a signal that is used to represent data as a sequence of separate values at any point in time. It can only take on one of a fixed number of values. This type of signal represents a real number within a constant range of values.
repeater user
The repeater user is usually operating in half duplex, using two frequencies but switching between transmit and receive.
Motorola Smart Zone
SmartConnect allows your radio to utilize in-vehicle LTE or Satellite modems to stay connected to the radio network. Go beyond the boundaries of your radio system with PTT communication through broadband connections.
