In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode frequency mixer. The mixing of each two frequencies results in the creation of two new frequencies, one at the sum of the two frequencies mixed, and the other at their difference. A low frequency produced in this manner is sometimes referred to as a beat. A beat frequency, or "beating," can be heard for example when multiple engines of an aircraft are running at close but not identical speeds, or two musical instruments are playing slightly out of tune. A superheterodyne receiver converts any selected incoming frequency by heterodyne action to a preselected common intermediate frequency, for example, 455 kilohertz or 10.7 megahertz, and provides amplification and selectivity, or filtering. The term heterodyne is sometimes also applied to one of the new frequencies produced by heterodyne signal mixing. Heterodyning is not confined to electrical signals, but can occur in any medium where signals of different frequencies are mixed, such as sound vibrations in the aircraft engine example given above. The human brain heterodynes stereo signals; by playing two tones with different frequencies (or the same audio with different phases), a beat frequency called binaural beat is produced inside the brain. As the human ear cannot detect the low frequencies required for this phenomenon, a pair of higher frequency tones must be used. People can use this phenomenon to alter their brain wave frequency, as the brain is an oscillator and can be externally driven. Optical stimulation is usually more successful, as much more of the human brain is devoted to processing visual information. Stimulation in this manner can produce changes in consciousness, as different brain wave frequencies are associated with unique states of mind. Epileptics and people otherwise sensitive to flashing lights should use caution with any brain wave stimulation technique. ==See also== *Ring modulation *Electroencephalography *Heterodyne detection Electronics terms
Could someone include a reference for the stuff (ahem) on brain behavior? At best it isn't well written (not clear which wave phenomenon in the brain is being referred to, e.g. the electrical pulses? If so, what is with the comment on low frequency as it relates to the ear?) At worst, it seems like unsupported pseudoscience. Thanks * In addition to what you said, I must say that even the introduction is pretty mushy: what happens when two instruments are playing out of tune is that their sounds get linearly mixed, and thus the sum of two sines at close frequencies is equal to the product of a "beating" sine at a low frequency and an "average" sine at the average frequency. Given that it is a product and not a sum, this does not mean that any new frequencies have been created: for example, if you high-pass it at a frequency higher than the "beating" frequency, the signal will be kept unchanged and the beating will be preserved... Which makes me wonder about the general correctness of [http://en.wikipedia.org/w/index.php?title=Heterodyne&diff=8852296&oldid=8408637 Gary D] and [http://en.wikipedia.org/w/index.php?title=Heterodyne&diff=5004424&oldid=4556994 Foobar]'s contributions, and their extrapolation to "brain waves". --User:Ma Baker 18:02, 11 Jun 2005 (UTC)
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Words begining with Heterodyne:
Heterodyne
Heterodyne
Heterodyne_detection
Heterodyne_principle
Heterodyne_repeater
Heterodyne
In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode frequency mixer. The mixing of each two frequencies results in the creation of two new frequencies, one at the sum of the two frequencies mixed, and the other at their difference. A low frequency produced in this manner is sometimes referred to as a beat. A beat frequency, or "beating," can be heard for example when multiple engines of an aircraft are running at close but not identical speeds, or two musical instruments are playing slightly out of tune. A superheterodyne receiver converts any selected incoming frequency by heterodyne action to a preselected common intermediate frequency, for example, 455 kilohertz or 10.7 megahertz, and provides amplification and selectivity, or filtering. The term heterodyne is sometimes also applied to one of the new frequencies produced by heterodyne signal mixing. Heterodyning is not confined to electrical signals, but can occur in any medium where signals of different frequencies are mixed, such as sound vibrations in the aircraft engine example given above. The human brain heterodynes stereo signals; by playing two tones with different frequencies (or the same audio with different phases), a beat frequency called binaural beat is produced inside the brain. As the human ear cannot detect the low frequencies required for this phenomenon, a pair of higher frequency tones must be used. People can use this phenomenon to alter their brain wave frequency, as the brain is an oscillator and can be externally driven. Optical stimulation is usually more successful, as much more of the human brain is devoted to processing visual information. Stimulation in this manner can produce changes in consciousness, as different brain wave frequencies are associated with unique states of mind. Epileptics and people otherwise sensitive to flashing lights should use caution with any brain wave stimulation technique. ==See also== *Ring modulation *Electroencephalography *Heterodyne detection Electronics terms
Heterodyne
Could someone include a reference for the stuff (ahem) on brain behavior? At best it isn't well written (not clear which wave phenomenon in the brain is being referred to, e.g. the electrical pulses? If so, what is with the comment on low frequency as it relates to the ear?) At worst, it seems like unsupported pseudoscience. Thanks * In addition to what you said, I must say that even the introduction is pretty mushy: what happens when two instruments are playing out of tune is that their sounds get linearly mixed, and thus the sum of two sines at close frequencies is equal to the product of a "beating" sine at a low frequency and an "average" sine at the average frequency. Given that it is a product and not a sum, this does not mean that any new frequencies have been created: for example, if you high-pass it at a frequency higher than the "beating" frequency, the signal will be kept unchanged and the beating will be preserved... Which makes me wonder about the general correctness of [http://en.wikipedia.org/w/index.php?title=Heterodyne&diff=8852296&oldid=8408637 Gary D] and [http://en.wikipedia.org/w/index.php?title=Heterodyne&diff=5004424&oldid=4556994 Foobar]'s contributions, and their extrapolation to "brain waves". --User:Ma Baker 18:02, 11 Jun 2005 (UTC)
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HA | HB | HC | HD | HE | HF | HG | HI | HJ | HK | HL | HM | HN | HO | HP | HR | HS | HT | HU | HW | HX | HY | HZ |Words begining with Heterodyne:
Heterodyne
Heterodyne
Heterodyne_detection
Heterodyne_principle
Heterodyne_repeater
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