Radio wave
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Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1mm, which is shorter than the diameter of a grain of rice. At 30 Hz the corresponding wavelength is ~10,000 kilometers, which is longer than the radius of the Earth. Wavelength of a radio wave is inversely proportional to its frequency, because its velocity is constant. Like all electromagnetic waves, radio waves in a vacuum travel at the speed of light, and in the Earth's atmosphere at a slightly slower speed. Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects. |
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| wikipedia:: Radio wave | |
| The Radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). | |
| wikipedia:: Radio spectrum |
frequencies from 3 Hz to 3,000 GHz (3 THz)
International telecommunication Union
Bands & Bandwidth
Frequency
Wavelength
phase
The tuned Electrical circuit, which allows the user of a radio to filter out all but a single station, is just one example of such a circuit.
Longwave
Mediumwave
Shortwave
Amateur radio frequencies
Amateur radio frequency allocations vary around the world. Several bands are common for amateurs worldwide, usually in the HF part of the spectrum. Other bands are national or regional allocations only due to differing allocations for other services, especially in the VHF and UHF parts of the radio spectrum.
Citizens' band and personal radio services
Citizens' band radio is allocated in many countries, using channelized radios in the upper HF part of the spectrum (around 27 MHz). It is used for personal, small business and hobby purposes. Other frequency allocations are used for similar services in different jurisdictions, for example UHF CB is allocated in Australia. A wide range of personal radio services exist around the world, usually emphasizing short-range communication between individuals or for small businesses, simplified license requirements or in some countries covered by a class license, and usually FM transceivers using around 1 watt or less.
Land mobile bands
Bands of frequencies, especially in the VHF and UHF parts of the spectrum, are allocated for communication between fixed base stations and land mobile vehicle-mounted or portable transceivers. In the United States these services are informally known as business band radio. See also Professional mobile radio.
Police radio and other public safety services such as fire departments and ambulances are generally found in the VHF and UHF parts of the spectrum. Trunking systems are often used to make most efficient use of the limited number of frequencies available.
The demand for mobile telephone service has led to large blocks of radio spectrum allocated to cellular frequencies.
Radio control
Reliable radio control uses bands dedicated to the purpose. Radio-controlled toys may use portions of unlicensed spectrum in the 27 MHz or 49 MHz bands, but more costly aircraft, boat, or land vehicle models use dedicated radio control frequencies near 72 MHz to avoid interference by unlicensed uses. The 21st century has seen a move to 2.4 GHz spread spectrum RC control systems.
Licensed amateur radio operators use portions of the 6-meter band in North America. Industrial remote control of cranes or railway locomotives use assigned frequencies that vary by area.
Radar
Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in the microwave part of the spectrum, although certain important applications for meteorology make use of powerful transmitters in the UHF band.
Inbox
- AIR band
- NOAA
- FRS 1-22
- Family radio service
- GMRS
- Similar to FRS
- Same frequency as FRS from 1-22 but have extra 8 channels
- If you have a license you can use the FRS channels at a higher wattage. Technically you are only supposed to use up to 3 or 4 watts or something? But with a license you can use at higher wattage. Though it's not strongly regulated regardless
- HAM Radio bands
- wide spectrum of frequencies
- radioreference.com
- Short wave
- CB Radio
- really low frequency
- VHF - broad categories
- UHF -
- LoRa - way high - 900s Hz
- The baofengs are technically HAM radios
- They are very unrestricted. You can broadcast on just about any frequency. Maybe not CB or LORA