Tuned filter
Encyclopedia
In signal processing
, a tuned filter is a stage in the processing channel which accepts or rejects signals which are tuned for a specific type.
. When choruses
sing in tune, the music reinforces itself with higher harmonic
s; aesthetically, the notes are more pleasing to the ear. But when signals are out of tune, dissonance
occurs; the effect is most noticeable for musical groups of small children, who have not been trained to sing in tune.
broadcasts. Stations learned to broadcast at a specific frequency
, and to share the bandwidth of the frequency spectrum
. Thus radio receivers had to have circuitry to tune to a specific carrier frequency
. This was accomplished by creating electronic filter
s which could accept specific frequency ranges, or tuned filters
.
broadcasting
transferred naturally to television
. However, as video techniques became more wide-spread, the types of tuning went beyond the simple radio and audio frequency ranges, to specific spatial discrimination of spatial frequencies
and textures.
Signal processing
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...
, a tuned filter is a stage in the processing channel which accepts or rejects signals which are tuned for a specific type.
History
Historically, the concept of tuning was to maintain a specific musical scaleMusical scale
In music, a scale is a sequence of musical notes in ascending and descending order. Most commonly, especially in the context of the common practice period, the notes of a scale will belong to a single key, thus providing material for or being used to conveniently represent part or all of a musical...
. When choruses
Choir
A choir, chorale or chorus is a musical ensemble of singers. Choral music, in turn, is the music written specifically for such an ensemble to perform.A body of singers who perform together as a group is called a choir or chorus...
sing in tune, the music reinforces itself with higher harmonic
Harmonic
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc. The harmonics have the property that they are all periodic at the fundamental...
s; aesthetically, the notes are more pleasing to the ear. But when signals are out of tune, dissonance
Consonance and dissonance
In music, a consonance is a harmony, chord, or interval considered stable, as opposed to a dissonance , which is considered to be unstable...
occurs; the effect is most noticeable for musical groups of small children, who have not been trained to sing in tune.
Radio
Tuning became important for the development of radioRadio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
broadcasts. Stations learned to broadcast at a specific frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
, and to share the bandwidth of the frequency spectrum
Frequency spectrum
The frequency spectrum of a time-domain signal is a representation of that signal in the frequency domain. The frequency spectrum can be generated via a Fourier transform of the signal, and the resulting values are usually presented as amplitude and phase, both plotted versus frequency.Any signal...
. Thus radio receivers had to have circuitry to tune to a specific carrier frequency
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
. This was accomplished by creating electronic filter
Electronic filter
Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both...
s which could accept specific frequency ranges, or tuned filters
Electronic filter
Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both...
.
Television and video
The specific techniques for audioSound
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...
broadcasting
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...
transferred naturally to television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
. However, as video techniques became more wide-spread, the types of tuning went beyond the simple radio and audio frequency ranges, to specific spatial discrimination of spatial frequencies
Spatial frequency
In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components of the structure repeat per unit of distance. The SI unit of spatial frequency is...
and textures.