Band III

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Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called high-band VHF, in contrast to Bands I and II.

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 range from around twenty thousand times per second to around three hundred billion times per second. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

Very high frequency class of radio waves

Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

Contents

Broadcast Television

North America

The band is subdivided into seven channels for television broadcasting, each occupying 6 MHz. [1]

Channel Frequency Range
7174-180 MHz
8180-186 MHz
9186-192 MHz
10192-198 MHz
11198-204 MHz
12204-210 MHz
13210-216 MHz

Europe

European Band III allocations vary from country to country, with channel widths of 7 or 8 MHz.

The standard channel allocations for European countries that use System B with 7 MHz channel spacing are as follows:

Channel Frequency Range
E5174-181 MHz
E6181-188 MHz
E7188-195 MHz
E8195-202 MHz
E9202-209 MHz
E10209-216 MHz
E11216-223 MHz
E12223-230 MHz

The Irish (8 MHz) system is shown below.

Channel Frequency Range
D174-182 MHz
E182-190 MHz
F190-198 MHz
G198-206 MHz
H206-214 MHz
i214-222 MHz
J222-230 MHz

Russia and other former members of OIRT

Russian analog television is transmitted using System D with 8 MHz channel bandwidth.

Channel Frequency Range
6174-182 MHz
7182-190 MHz
8190-198 MHz
9198-206 MHz
10206-214 MHz
11214-222 MHz
12222-230 MHz

Radio

The band came into use for radio broadcasting at the turn of the 21st century and is used for Digital Audio Broadcasting.

Digital audio broadcasting digital radio standard

Digital audio broadcasting (DAB) is a digital radio standard for broadcasting digital audio radio services, used in many countries around the world, though not North America.

It is subdivided into a number of frequency blocks:

Block Centre Frequency
5A174.928 MHz
5B176.640 MHz
5C178.352 MHz
5D180.064 MHz
6A181.936 MHz
6B183.648 MHz
6C185.360 MHz
6D187.072 MHz
7A188.928 MHz
7B190.640 MHz
7C192.352 MHz
7D194.064 MHz
8A195.936 MHz
8B197.648 MHz
8C199.360 MHz
8D201.072 MHz
9A202.928 MHz
9B204.640 MHz
9C206.352 MHz
9D208.064 MHz
10A209.936 MHz
10B211.648 MHz
10C213.360 MHz
10D215.072 MHz
10N210.096 MHz
11A216.928 MHz
11B218.640 MHz
11C220.352 MHz
11D222.064 MHz
11N217.088 MHz
12A223.936 MHz
12B225.648 MHz
12C227.360 MHz
12D229.072 MHz
12N224.096 MHz
13A230.784 MHz
13B232.496 MHz
13C234.208 MHz
13D235.776 MHz
13E237.488 MHz
13F239.200 MHz

Worldwide usage

Europe

In the UK and part of Ireland, Band III was originally used for monochrome 405-line television; however, this was discontinued by the mid-1980s. Other European countries (including Ireland) continued to use Band III for analogue 625-line colour television.

Monochrome shades of one color; describes paintings, drawings, design, or photographs in one color or values of one color, having only one colour

A monochromic image is composed of one color. The term monochrome comes from the Ancient Greek: μονόχρωμος, translit. monochromos, lit. 'having one color'.

Television telecommunication medium for transmitting and receiving moving images

Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome, or in colour, and in two or three dimensions and sound. The term can refer to a television set, a television program, or the medium of television transmission. Television is a mass medium for advertising, entertainment and news.

576i standard-definition video mode

576i is a standard-definition video mode originally used for broadcast television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because of its close association with the color encoding system, it is often referred to as simply PAL, PAL/SECAM or SECAM when compared to its 60 Hz NTSC-color-encoded counterpart, 480i. In digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines", and the aspect ratio is usually 4:3 in analogue transmission and 16:9 in digital transmission.

Digital television in the DVB-T standard can be used in conjunction with VHF Band III and is used as such in some places. The use of sub-band 2 and sub-band 3 band for Digital Audio Broadcasting is now being widely adopted. Sub-band 1 is used for MPT-1327 trunked PMR radio, remote wireless microphones and PMSE links.

North America

In North America, use of the band for color television broadcasts is still widespread. Favorable propagation characteristics and reasonable power limits (up to 65  kW for full-power digital television, versus 20 kW or less on VHF Band I) has meant that many US broadcasters elected to move their full-power ATSC stations from UHF frequencies to Band III VHF when all full-power NTSC analog television services in the US shut down in 2009. [2]

Related Research Articles

Ultra high frequency radio waves

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.

Terrestrial television television content transmitted via signals in the air

Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television, in which the television signal is transmitted to the receiver from an overhead satellite, and cable television, in which the signal is carried to the receiver through a cable.

In-band on-channel (IBOC) is a hybrid method of transmitting digital radio and analog radio broadcast signals simultaneously on the same frequency.

The FM broadcast band, used for FM broadcast radio by radio stations, differs between different parts of the world. In Europe, Australia and Africa ( ), it spans from 87.5 to 108 megahertz (MHz) - also known as VHF Band II - while in the Americas it ranges from 88 to 108 MHz. The FM broadcast band in Japan uses 76 to 95 MHz. The International Radio and Television Organisation (OIRT) band in Eastern Europe is from 65.8 to 74.0 MHz, although these countries now primarily use the 87.5 to 108 MHz band, as in the case of Russia. Some other countries have already discontinued the OIRT band and have changed to the 87.5 to 108 MHz band.

Terrestrial television systems are encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analogue television systems in use around the world until the late 2010s (expected): NTSC, PAL, and SECAM. Now in digital terrestrial television (DTT), there are four main systems in use around the world: ATSC, DVB, ISDB and DTMB.

Tuner (radio) frequency selection subsystem for a radio receiver

A tuner is a subsystem that receives radio frequency (RF) transmissions like radio broadcasts and converts the selected carrier frequency and its associated bandwidth into a fixed frequency that is suitable for further processing, usually because a lower frequency is used on the output. Broadcast FM/AM transmissions usually feed this intermediate frequency (IF) directly into a demodulator that convert the radio signal into audio-frequency signals that can be fed into an amplifier to drive a loudspeaker.

Television channel frequencies Wikimedia list article

The following tables show the frequencies assigned to broadcast television channels in various regions of the world, along with the ITU letter designator for the system used. The frequencies shown are for the analogue video and audio carriers. The channel itself occupies several megahertz of bandwidth. For example, North American channel 2 occupies the spectrum from 54 to 60 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator.

In North American broadcast television frequencies, channel 1 is a former broadcast (over-the-air) television channel. During the experimental era of TV operation, Channel 1 was moved around the lower VHF spectrum repeatedly, with the entire band displaced upward at one point due to an early 40 MHz allocation for the FM broadcast band.

FM broadcasting

FM broadcasting is a method of radio broadcasting using frequency modulation (FM) technology. Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high-fidelity sound over broadcast radio. FM broadcasting is capable of better sound quality than AM broadcasting, the chief competing radio broadcasting technology, so it is used for most music broadcasts. Theoretically wideband AM can offer equally good sound quality, provided the reception conditions are ideal. FM radio stations use the VHF frequencies. The term "FM band" describes the frequency band in a given country which is dedicated to FM broadcasting.

Channel 37 is a purposefully unused ultra-high frequency (UHF) television broadcasting television channel in the United States, Canada and Mexico. The frequency range allocated to this channel is important for radio astronomy, so broadcasting is not licensed.

A digital channel election was the process by which television stations in the United States chose which physical radio-frequency TV channel they would permanently use after the analog shutdown in 2009. The process was managed and mandated by the Federal Communications Commission for all full-power TV stations. Low-powered television (LPTV) stations are going through a somewhat different process, and are also allowed to flash-cut to digital.

Band II is the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 87.5 to 108.0 megahertz (MHz).

Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in line to ITU Radio Regulations. Channel spacings vary from country to country, with spacings of 6, 7 and 8 MHz being common.

Television frequency allocation has evolved since the start of television in Australia in 1956, and later in New Zealand in 1960. There was no coordination between the national spectrum management authorities in either country to establish the frequency allocations. The management of the spectrum in both countries is largely the product of their economical and political situation. New Zealand didn't start to develop television service until 1965 due to World War 2 and its economic harm in the country's economy.

CCIR System B was the 625-line analog broadcast television system which at its peak was the system used in most countries. It is being replaced across Western Europe, part of Asia and Africa by digital broadcasting.

UHF television broadcasting

UHF television broadcasting is the use of ultra high frequency (UHF) radio for over-the-air transmission of television signals. UHF frequencies are used for both analog and digital television broadcasts. UHF channels are typically given higher channel numbers, like the US arrangement with VHF channels 2 to 13, and UHF channels numbered 14 to 83.

The Pan-American television frequencies are different for terrestrial and cable television systems. Terrestrial television channels are divided into two bands: the VHF band which comprises channels 2 through 13 and occupies frequencies between 54 through 216 MHz, and the UHF band, which comprises channels 14 through 83 and occupies frequencies between 470 and 890 MHz. These bands are different enough in frequency that they often require separate antennas to receive, and separate tuning controls on the television set. The VHF band is further divided into two frequency ranges: VHF low band between 54 and 88 MHz, containing channels 2 through 6, and VHF high band between 174 and 216 MHz, containing channels 7 through 13. The wide spacing between these frequency bands is responsible for the complicated design of rooftop TV antennas. The UHF band has higher noise and greater attenuation, so higher gain antennas are often required for UHF.

CCIR System A was the 405 line analog broadcast television system broadcast in the UK and Ireland. CCIR service was discontinued in 1985.

CCIR System I is an analog broadcast television system. It was first used in the Republic of Ireland starting in 1962 as the 625-line broadcasting standard to be used on VHF Band I and Band III, sharing Band III with 405-line System A signals radiated in the north of the country. The UK started its own 625-line television service in 1964 also using System I, but on UHF only - the UK has never used VHF for 625-line television except for some cable relay distribution systems.

References