Tuner (radio)
Encyclopedia
A radio tuner is a subsystem that receives radio broadcasts and converts them into audio-frequency signals which can be fed into an amplifier
driving a loudspeaker
. FM
tuner, AM
tuner, Digital Audio Broadcasting
DAB tuner, etc. are types of radio tuner dealing with transmissions using different methods of modulation
. The term tuner can mean either part of a radio receiver or standalone audio components that are part of an audio system
, to be connected to a separate amplifier. The verb tuning in radio contexts means adjusting the radio receiver to receive the desired radio signal from a particular radio station
.
and capacitor
connected in parallel, where the capacitor or inductor is made to be variable. This creates a resonant circuit
which responds to an alternating current of one frequency. Combined with a detector
, also known as a demodulator, (diode D-1, in the circuit), it becomes the simplest radio receiver, often called a crystal set
.
Practical radio tuners use a superheterodyne receiver
. Older models would realize manual tuning by means of mechanically operated ganged variable capacitors. Often several sections would be provided on a tuning capacitor, to tune several stages of the receiver in tandem, or to allow switching between different freqeuncy bands. A later method used a potentiometer
supplying a variable voltage to varactor diodes in the local oscillator and tank circuits of front end tuner, for electronic tuning. Still later, phase locked loop methods were used, with microprocessor
control.
In a self-contained radio receiver, the signal from the detector after the tuner is run through a volume control and to an amplifier stage. The amplifier feeds either an internal speaker or headphones. In a tuner component of an audio system (for example, a home high-fidelity system or a public address system in a building), the output of the detector is connected to a separate external system of amplifiers and speakers.
The broadcast FM band (88 to 108MHz in most countries) is around one hundred times higher in frequency than the AM band and provides enough space for a bandwidth of 50kHz. This bandwidth is sufficient to transmit both stereo channels with almost the full bandwidth of the human ear. Sometimes, additional subcarriers are used for unrelated audio or data transmissions. The left and right audio signals must be combined into a single signal which is applied to the modulation input of the transmitter; this is done by the addition of an inaudible subcarrier signal to the FM broadcast signal. FM stereo allows left and right channels to be transmitted. The availability of FM stereo, a quieter VHF broadcast band, and better fidelity lead to the specialization of FM broadcasting
in music, tending to leave AM broadcasting with spoken-word material.
and TV/FM DX applications, especially those produced in the 1970s and early 1980s, when performance and manufacturing standards were among the highest. In many instances the tuner may be modified to improve performance. A growing hobby trend is the electronics specialists that buy, collect and restore these vintage FM or AM/FM audio tuners. The restoration usually begins with replacing the electrolytics (capacitors) that age over time. The tuner is outfitted with improved tolerance and better sounding upgraded parts. Prices have increased relative to the increasing demand for the older audio tuners. Those with the most value are the best sounding, most rare (collectible), the best DX capable (Distance Reception) and the known build quality of the component, as it left the factory.
for FM broadcasts.
In Europe, where a second AM broadcast band is used for longwave broadcasting
, tuners may be fitted with both the standard medium wave and the additional longwave band. However, radios with only medium wave are also common, especially in countries where there are no longwave broadcasters. Rarely, radios are sold with only FM and longwave, but no medium wave band.
analog television
or digital television
transmission into audio
and video
signals which can be further processed to produce sound
and a picture. Different tuners are used for different television standards
such as PAL
, NTSC
, ATSC
, SECAM
, DVB-C
, DVB-T
, ISDB
, T-DMB, open cable.
Analog tuners can tune only analog signal
s. An ATSC tuner
is a digital tuner that tunes digital signal
s only and yet some digital tuners have an analog bypasses.
VHF/UHF TV tuners are rarely found as a separate component, instead are incorporated into television set
s. Cable box
es are set top boxs that serve as a separate tuner, and have channel 3/4 outputs for TV sets that aren't cable-ready. They often feature composite
, S-video
, or component video
outputs so they can be used on video monitor
s that do not have a TV tuner, or direct video inputs. They are usually bundled with a video monitor
, VCR, and/or digital video recorder
(DVR).
TV tuner card
are also installed on PCI
computer
expansion cards (or in USB device, or even as a part of video card
), together with a Digital signal processor
(DSP), allowing a personal computer
to display and/or capture television channel
s. A number of earlier models were stand-alone tuners, designed to deliver TV picture through a VGA connector
. This allowed viewing television on a computer display, but, of course, did not allow recording television program
s by the PC.
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
driving a loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
. FM
Frequency modulation
In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
tuner, AM
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
tuner, Digital Audio Broadcasting
Digital audio broadcasting
Digital Audio Broadcasting is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format....
DAB tuner, etc. are types of radio tuner dealing with transmissions using different methods of modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
. The term tuner can mean either part of a radio receiver or standalone audio components that are part of an audio system
Sound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
, to be connected to a separate amplifier. The verb tuning in radio contexts means adjusting the radio receiver to receive the desired radio signal from a particular radio station
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
.
Design
The simplest tuner consists of an inductorInductor
An inductor is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
and capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
connected in parallel, where the capacitor or inductor is made to be variable. This creates a resonant circuit
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
which responds to an alternating current of one frequency. Combined with a detector
Detector (radio)
A detector is a device that recovers information of interest contained in a modulated wave. The term dates from the early days of radio when all transmissions were in Morse code, and it was only necessary to detect the presence of a radio wave using a device such as a coherer without necessarily...
, also known as a demodulator, (diode D-1, in the circuit), it becomes the simplest radio receiver, often called a crystal set
Crystal radio receiver
thumb|Boy listening to a modern crystal radioA crystal radio receiver, also called a crystal set or cat's whisker receiver, is a very simple radio receiver, popular in the early days of radio. It needs no battery or power source and runs on the power received from radio waves by a long wire antenna...
.
Practical radio tuners use a superheterodyne receiver
Superheterodyne receiver
In electronics, a superheterodyne receiver uses frequency mixing or heterodyning to convert a received signal to a fixed intermediate frequency, which can be more conveniently processed than the original radio carrier frequency...
. Older models would realize manual tuning by means of mechanically operated ganged variable capacitors. Often several sections would be provided on a tuning capacitor, to tune several stages of the receiver in tandem, or to allow switching between different freqeuncy bands. A later method used a potentiometer
Potentiometer
A potentiometer , informally, a pot, is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used , it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as volume controls on...
supplying a variable voltage to varactor diodes in the local oscillator and tank circuits of front end tuner, for electronic tuning. Still later, phase locked loop methods were used, with microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
control.
In a self-contained radio receiver, the signal from the detector after the tuner is run through a volume control and to an amplifier stage. The amplifier feeds either an internal speaker or headphones. In a tuner component of an audio system (for example, a home high-fidelity system or a public address system in a building), the output of the detector is connected to a separate external system of amplifiers and speakers.
The broadcast FM band (88 to 108MHz in most countries) is around one hundred times higher in frequency than the AM band and provides enough space for a bandwidth of 50kHz. This bandwidth is sufficient to transmit both stereo channels with almost the full bandwidth of the human ear. Sometimes, additional subcarriers are used for unrelated audio or data transmissions. The left and right audio signals must be combined into a single signal which is applied to the modulation input of the transmitter; this is done by the addition of an inaudible subcarrier signal to the FM broadcast signal. FM stereo allows left and right channels to be transmitted. The availability of FM stereo, a quieter VHF broadcast band, and better fidelity lead to the specialization of FM broadcasting
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
in music, tending to leave AM broadcasting with spoken-word material.
Restoration
Standalone audio stereo FM tuners are sought after for audiophileAudiophile
An audiophile is a person who enjoys listening to recorded music, usually in a home. Some audiophiles are more interested in collecting and listening to music, while others are more interested in collecting and listening to audio components, whose "sound quality" they consider as important as the...
and TV/FM DX applications, especially those produced in the 1970s and early 1980s, when performance and manufacturing standards were among the highest. In many instances the tuner may be modified to improve performance. A growing hobby trend is the electronics specialists that buy, collect and restore these vintage FM or AM/FM audio tuners. The restoration usually begins with replacing the electrolytics (capacitors) that age over time. The tuner is outfitted with improved tolerance and better sounding upgraded parts. Prices have increased relative to the increasing demand for the older audio tuners. Those with the most value are the best sounding, most rare (collectible), the best DX capable (Distance Reception) and the known build quality of the component, as it left the factory.
AM/FM
Most of the top end audio tuner models were designed and manufactured to receive only the FM broadcast band. As FM became more popular, the limitations of AM became more apparent, and FM became the primary listening focus, especially for stereo and music broadcasting. The bulk of tuners made for the market, however, were AM/FM design, especially in the 1980s and 1990s. Few companies even manufacture dedicated FM or AM/FM tuners now, as these bands are most often included in a low cost chip for A/V systems, more as an afterthought, rather than designed for the critical FM listener. The FM aficionado must really look to the classic tuner models and either rebuild or upgrade the unit to satisfy demanding FM listeners. A few 1970s tuners feature now-deprecated Dolby noise reductionDolby noise reduction system
Dolby NR is the name given to a series of noise reduction systems developed by Dolby Laboratories for use in analog magnetic tape recording. The first was Dolby A, a professional broadband noise reduction for recording studios in 1966, but the best-known is Dolby B , a sliding band system for the...
for FM broadcasts.
In Europe, where a second AM broadcast band is used for longwave broadcasting
Longwave
In radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...
, tuners may be fitted with both the standard medium wave and the additional longwave band. However, radios with only medium wave are also common, especially in countries where there are no longwave broadcasters. Rarely, radios are sold with only FM and longwave, but no medium wave band.
Television
A television tuner converts an radio frequencyRadio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
analog television
Analog television
Analog television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the message conveyed by the broadcast signal is a function of deliberate variations in the amplitude and/or frequency of the signal...
or digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
transmission into audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
and video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
signals which can be further processed to produce sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
and a picture. Different tuners are used for different television standards
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
such as PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
, NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
, ATSC
ATSC
ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....
, SECAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....
, DVB-C
DVB-C
DVB-C stands for Digital Video Broadcasting - Cable and it is the DVB European consortium standard for the broadcast transmission of digital television over cable...
, DVB-T
DVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
, ISDB
ISDB
Integrated Services Digital Broadcasting is a Japanese standard for digital television and digital radio used by the country's radio and television stations. ISDB replaced the previously used MUSE "Hi-vision" analogue HDTV system...
, T-DMB, open cable.
Analog tuners can tune only analog signal
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
s. An ATSC tuner
ATSC tuner
An ATSC tuner, often called an ATSC receiver or HDTV tuner is a type of television tuner that allows reception of digital television television channels transmitted by television stations in North America, parts of Central America and South Korea that use ATSC standards...
is a digital tuner that tunes digital signal
Digital signal
A digital signal is a physical signal that is a representation of a sequence of discrete values , for example of an arbitrary bit stream, or of a digitized analog signal...
s only and yet some digital tuners have an analog bypasses.
VHF/UHF TV tuners are rarely found as a separate component, instead are incorporated into television set
Television set
A television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...
s. Cable box
Cable box
The term cable box can refer to:* Cable box an electronic device that controls cable television in individual homes.* Cable box a box located outside a residence that connects cable television....
es are set top boxs that serve as a separate tuner, and have channel 3/4 outputs for TV sets that aren't cable-ready. They often feature composite
Composite video
Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...
, S-video
S-Video
Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...
, or component video
Component video
Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...
outputs so they can be used on video monitor
Video monitor
A video monitor also called a broadcast monitor, broadcast reference monitor or just reference monitor, is a display device similar to a television set, used to monitor the output of a video-generating device, such as playout from a video server, IRD, video camera, VCR, or DVD player. It may or...
s that do not have a TV tuner, or direct video inputs. They are usually bundled with a video monitor
Video monitor
A video monitor also called a broadcast monitor, broadcast reference monitor or just reference monitor, is a display device similar to a television set, used to monitor the output of a video-generating device, such as playout from a video server, IRD, video camera, VCR, or DVD player. It may or...
, VCR, and/or digital video recorder
Digital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...
(DVR).
TV tuner card
TV tuner card
A TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the Tivo digital video recorder does.-Variants: The interfaces for...
are also installed on PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
expansion cards (or in USB device, or even as a part of video card
Video card
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
), together with a Digital signal processor
Digital signal processor
A digital signal processor is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.-Typical characteristics:...
(DSP), allowing a personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
to display and/or capture television channel
Television channel
A television channel is a physical or virtual channel over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the broadcast or cable band of 54 to 60 MHz, with carrier frequencies of 55.25 MHz for NTSC analog video and...
s. A number of earlier models were stand-alone tuners, designed to deliver TV picture through a VGA connector
VGA connector
A Video Graphics Array connector is a three-row 15-pin DE-15 connector. The 15-pin VGA connector is found on many video cards, computer monitors, and some high definition television sets...
. This allowed viewing television on a computer display, but, of course, did not allow recording television program
Television program
A television program , also called television show, is a segment of content which is intended to be broadcast on television. It may be a one-time production or part of a periodically recurring series...
s by the PC.
See also
- Analog passthroughAnalog passthroughAnalog passthrough is a feature found on some digital-to-analog television converter boxes. Boxes without analog passthrough only allow digital TV to be viewed on older, analog-only TVs...
- ATSC tunerATSC tunerAn ATSC tuner, often called an ATSC receiver or HDTV tuner is a type of television tuner that allows reception of digital television television channels transmitted by television stations in North America, parts of Central America and South Korea that use ATSC standards...
- Cable converter
- Digital television adapterDigital television adapterA digital television adapter , or digital-to-analog converter [set-top box], or commonly known as a converter box, it is a television tuner that receives a digital television transmission, and converts the digital signal into an analog signal that can be received and displayed on an analog...
(DTA) - QAM tunerQAM tunerQAM stands for quadrature amplitude modulation, the format by which digital cable channels are encoded and transmitted via cable television providers...
- Radio antenna
- Receiver (radio)Receiver (radio)A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
- Set top box
- Television antennaTelevision antennaA television antenna, or TV aerial, is an antenna specifically designed for the reception of over the air broadcast television signals, which are transmitted at frequencies from about 41 to 250 MHz in the VHF band, and 470 to 960 MHz in the UHF band in different countries...
- Television setTelevision setA television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...
- TV tuner cardTV tuner cardA TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the Tivo digital video recorder does.-Variants: The interfaces for...
- Receiver (radio)Receiver (radio)A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...
- Television setTelevision setA television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...
- Tuner (television)