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