Ring modulation is a signal-processing effect in electronics, related to amplitude modulation or frequency mixing, performed by multiplying two signals, where one is typically a sine-wave or another simple waveform. Amplitude modulation ( AM) is a technique used in electronic communication most commonly for transmitting information via a Radio Carrier wave In Telecommunication, a mixer is a Nonlinear or time-varying circuit or device that accepts as its Input two different frequencies and presents It is referred to as "ring" modulation because the analog circuit of diodes originally used to implement this technique took the shape of a ring. Analogue electronics (or analog in American English) are those electronic systems with a continuously Variable signal Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes This circuit is similar to a bridge rectifier, except that instead of the diodes facing "left" or "right", they go "clockwise" or "anti-clockwise". A diode bridge or bridge rectifier is an arrangement of four diodes in a bridge configuration that provides the same polarity of output
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Examples
These are some audio samples of the ring modulation effect:
Unprocessed original sample Ring modulation with a 2500 Hz sound Notice the bell-like sound. Ring modulation with an exponential sweep from 0 Hz to 9 kHz On lower modulation frequencies, the ring modulation is perceived as a tremolo effect (as in the first part of the sound) - Problems playing the files? See media help.
Operation
Ring modulators combine (or heterodyne) two waveforms, and output the sum and difference of the frequencies present in each waveform. In Radio and Signal processing, heterodyning is the generation of new frequencies by mixing or multiplying two Oscillating waveforms waveformogg|right|a sine square and sawtooth wave at 440 hz]] Waveform means the shape and form of a signal such as a Wave moving in a solid liquid or gaseous This process of ring modulation produces a signal rich in overtones, suitable for producing bell-like or otherwise metallic sounds. An overtone is a natural resonance or vibration frequency of a system
Two oscillators, whose frequencies were harmonically related and ring modulated against each other, produce sounds that still adhered to the overtones of the notes, but contain a very different spectral make up.
If the same signal is sent to both inputs of a ring modulator, the resultant harmonic spectrum is the original frequency domain doubled(If f1 = f2 = f , f2 − f1 = 0 and f2 + f1 = 2f). However, some distortion occurs due to the forward voltage drop of the diodes.
Some modern ring modulators are implemented using digital signal processing techniques by simply multiplying the time domain signals, producing a mathematically perfect signal output. Digital signal processing ( DSP) is concerned with the representation of the signals by a sequence of numbers or symbols and the processing of these signals Time domain is a term used to describe the analysis of mathematical functions or physical signals with respect to Time.
Multiplication in the time domain is the same as convolution in the frequency domain, so the output waveform contains the sum and difference of the input frequencies. Time domain is a term used to describe the analysis of mathematical functions or physical signals with respect to Time. In Mathematics and in particular Functional analysis, convolution is a mathematical operation on two functions f and Frequency domain is a term used to describe the analysis of Mathematical functions or signals with respect to frequency Thus, in the basic case where two sine waves of frequencies f1 and f2 (f2 > f1) are multiplied, two new sine waves are created, with one at f1 + f2 and the other at f2 − f1. The two new waves are unlikely to be harmonically related and(in a well designed ring modulator) the original signals are not present. It is this that gives the ring modulator its unique tones.
Intermodulation products can be generated by carefully selecting and changing the frequency of the two input waveforms. Intermodulation or intermodulation distortion ( IMD) or intermod for short Frequency is a measure of the number of occurrences of a repeating event per unit Time. waveformogg|right|a sine square and sawtooth wave at 440 hz]] Waveform means the shape and form of a signal such as a Wave moving in a solid liquid or gaseous If the signals are processed digitally, the frequency-domain convolution becomes circular convolution. A circular Convolution of two functions is defined in terms of the periodic extension of one or both functions If the signals are wideband, this will cause aliasing distortion, so it is common to oversample the operation or filter the signals prior to ring modulation. In communications, wideband is a relative term used to describe a wide range of frequencies in a Spectrum. This article applies to signal processing including computer graphics In Signal processing, oversampling is the process of sampling a signal with a Sampling frequency significantly higher than twice the bandwidth
Integrated circuit methods of ring modulation
On the C64 SID chip, ring modulation multiplies a triangle wave with a square wave. The MOS Technology 6581/8580 SID (Sound Interface Device was the built-in Programmable Sound Generator chip of Commodore 's CBM-II, A triangle wave is a Non-sinusoidal Waveform named for its triangular shape A square wave is a kind of Non-sinusoidal waveform, most typically encountered in Electronics and Signal processing.
On an ARP Odyssey synthesizer the ring modulator is an XOR function (formed from two NAND gates) fed from the square wave outputs of the two oscillators. The ARP Odyssey was an analog Synthesizer introduced in 1972 Responding to pressure from Moog Music to create a portable affordable (the Though not equivalent to ring modulation, with square waves the resulting sound is quite similar.
Use in music
Ring modulators are mostly used in synthesizers and a ring modulator module was a common feature on early modular Moog synthesizers. The term Moog (ˈmoʊg as in 'vogue' Synthesizer can refer to any number of Analog synthesizers designed by Dr The ring modulator went out of fashion with the advent of all-in-one synthesizers and sampled-based synthesizers, but has returned as a feature in digital modelling and software synthesizers. A software synthesizer also known as a softsynth or virtual instrument is a Computer program for Digital audio generation
It was a very commonly used effect in early electronic music, when analog oscillators were only capable of generating waveforms with a predictable series of overtones. One of the best-known applications of the ring modulator was its use by Brian Hodgson of the BBC Radiophonic Workshop to produce the distinctive voice of the Daleks in the television series Doctor Who. Brian Hodgson is a British television Composer and sound technician A Dalek (, ˈdɑːlεk is a member of a Fictional extraterrestrial race of Mutants from the British science fiction television A television program (US television programme (UK or television show (U Doctor Who is a British science fiction television programme produced by the BBC.
A ring modulator effect is added to the guitar solo in the song "Paranoid" by Black Sabbath. " Paranoid " is a song by Black Sabbath that appears on the band's second album Paranoid. Black Sabbath are an
In one of the lineups during the 1970s electric period of Miles Davis, Chick Corea played a Rhodes piano through a ring modulator. Miles Dewey Davis III (May 26 1926 &ndash September 28 1991 was an American Jazz Trumpeter, Bandleader, and Composer. Armando Anthony "Chick" Corea (born June 12, 1941) is a multiple Grammy Award winning American Jazz Pianist A Rhodes piano is an electromechanical Musical instrument, a brand of Electric piano. This gave the distinctive electric piano a very different and unusual sound. It can be seen and heard on a DVD release of Davis' performance at the Isle of Wight.
Early electronic composers, particularly Stockhausen, used ring-modulator effects. Stockhausen's compositions Kontakte (1958–60) and Telemusik (1966) call for it and, indeed, whole compositions are based around it, such as Mikrophonie II (1965, where the sounds of choral voices are modulated with a Hammond organ), Mantra (1970, where the sounds from two pianos are routed through ring modulators), and Licht-Bilder from Sonntag aus Licht (2002), which ring-modulates flute and trumpet. Kontakte ("Contacts" is a celebrated Electronic music work by Karlheinz Stockhausen, realized in 1958 - 60 at the Telemusik is an electronic composition by Karlheinz Stockhausen. Mikrophonie is the title given by Karlheinz Stockhausen to two of his compositions written in 1964 and 1965 in which “normally inaudible vibrations. The Hammond organ is an electric organ which was invented by Laurens Hammond in 1934 and manufactured by the Hammond Organ Company Mantra is a composition by the German composer Karlheinz Stockhausen. Licht (Light subtitled "The Seven Days of the Week" is a cycle of seven Operas composed by Karlheinz Stockhausen which in total lasts over
Other applications
Ring modulation was also extensively used in old radio receivers. Ring modulators were used to demodulate the FM stereo signal. Examples include the HH Scott 310, 335, 345, 370B, and Fisher 500c.
Jon Lord from Deep Purple often used the Ring Modulator with his Hammond organ during live shows (Made in Japan, California Jam), and sometimes even in studio records (Rat Bat Blue).
Luke Vibert showcases the ring modulator sound in the "Fused into music", on his album, Big Soup. Luke Vibert is a British recording artist and producer known for his work in many subgenres of Electronica.
Nicholas Briggs (voice of the Daleks and the Cybermen in the BBC science fiction series Doctor Who) uses a Ring Modulator to alter his voice. Nicholas Briggs is a British actor and writer predominantly associated with the BBC Science fiction Television series Doctor Who A Dalek (, ˈdɑːlεk is a member of a Fictional extraterrestrial race of Mutants from the British science fiction television The Cybermen are a Fictional race of Cyborgs who are amongst the most persistent enemies of the Doctor in the British Science fiction television Doctor Who is a British science fiction television programme produced by the BBC.
See also
External links
- Harmony Central: Effects Explained: Ring Modulation by Scott Lehman
- [1] A homebuilt stereo FM tuner that uses a ring modulator to decode the FM stereo signal
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