Curiosity : Something behind TV and Radio

Watching TVWhile watching TV or Listening to FM Radio, what we do? We switch between channels/stations which in fact is tuning the frequencies  of  electromagnetic spectrum which are measured in Hertz (Hz). By the way who regulates this? What frequency is used for what purpose? Is there any standards? Know more now…

Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz. Electromagnetic waves in this frequency range, called radio waves, are used for radio communication and various other applications.

So, your TV or Radio Stations produce the radio waves which you receive and enjoy.

Who can generate the Radio waves? Who controls it? 

The generation of radio waves is strictly regulated by the government in most countries, coordinated by an international standards body called the International Telecommunications Union (ITU). Different parts of the radio spectrum are allocated for different radio transmission technologies and applications. In some cases, parts of the radio spectrum is sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum)

Flag of ITU.svgITU is a specialized agency of the United Nations (UN) that is responsible for issues that concern information and communication technologies. The ITU coordinates the shared global use of the radio spectrum, promotes international cooperation in assigning satellite orbits, works to improve telecommunication infrastructure in the developing world, and assists in the development and coordination of worldwide technical standards. The ITU is active in areas including broadband Internet, latest-generation wireless technologies, aeronautical and maritime navigation, radio astronomy, satellite-based meteorology, convergence in fixed-mobile phone, Internet access, data, voice, TV broadcasting, and next-generation networks.

ITU, based in Geneva, Switzerland, is a member of the United Nations Development Group. Its membership includes 193 Member States and around 700 Sector Members and Associates.

Okay, what are the frequencies or wave lengths used by our Televisions? What about our mobile phones?

Well, the ITU regulates it along with governments of various countries and allocates the frequencies as bands, for various purposes. The list below will explain the typical allocation.

band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose. Above 300 GHz, the absorption of electromagnetic radiation by Earth’s atmosphere is so great that the atmosphere is effectively opaque, until it becomes transparent again in the near-infrared and optical window frequency ranges.

To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies. Each of these bands has a basic bandplan which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers.

Band name Abbreviation ITU band Frequency
and
wavelength in air
Example uses
Tremendously low frequency TLF   < 3 Hz
> 100,000 km
Natural and artificial electromagnetic noise
Extremely low frequency ELF   3–30 Hz
100,000 km – 10,000 km
Communication with submarines
Super low frequency SLF   30–300 Hz
10,000 km – 1000 km
Communication with submarines
Ultra low frequency ULF   300–3000 Hz
1000 km – 100 km
Submarine communication, Communication within mines
Very low frequency VLF 4 3–30 kHz
100 km – 10 km
Navigationtime signals, submarine communication, wireless heart rate monitorsgeophysics
Low frequency LF 5 30–300 kHz
10 km – 1 km
Navigation, time signals, AM longwavebroadcasting (Europe and parts of Asia),RFIDamateur radio
Medium frequency MF 6 300–3000 kHz
1 km – 100 m
AM (medium-wave) broadcasts, amateur radio, avalanche beacons
High frequency HF 7 3–30 MHz
100 m – 10 m
Shortwave broadcasts, citizens’ band radio, amateur radio and over-the-horizon aviation communications, RFIDOver-the-horizon radarAutomatic link establishment (ALE) /Near Vertical Incidence Skywave (NVIS) radio communications, Marine and mobile radio telephony
Very high frequency VHF 8 30–300 MHz
10 m – 1 m
FMtelevision broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications, amateur radio,weather radio
Ultra high frequency UHF 9 300–3000 MHz
1 m – 100 mm
Television broadcasts, Microwave oven,Microwave devices/communications, radio astronomymobile phoneswireless LAN,BluetoothZigBeeGPS and two-way radios such as Land Mobile, FRS and GMRSradios, amateur radio
Super high frequency SHF 10 3–30 GHz
100 mm – 10 mm
Radio astronomy, microwave devices/communications, wireless LAN, most modern radarscommunications satellites, satellite television broadcasting,DBS, amateur radio
Extremely high frequency EHF 11 30–300 GHz
10 mm – 1 mm
Radio astronomy, high-frequencymicrowave radio relay, microwave remote sensing, amateur radio, directed-energy weaponmillimeter wave scanner
Terahertz orTremendously high frequency THz or THF 12 300–3,000 GHz
1 mm – 100 μm
Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics,condensed-matter physicsterahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio

Courtesy : Wikipedia and ITU

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