Heterodyning is acclimated actual broadly in communications engineering to accomplish new frequencies and move advice from one abundance approach to another. Besides its use in the superheterodyne ambit which is begin in about all radio and television receivers, it is acclimated in radio transmitters, modems, agenda communications and set-top boxes, radar, radio telescopes, telemetry systems, corpuscle phones, cable television advocate boxes and headends, bake relays, metal detectors, diminutive clocks, and aggressive cyberbanking countermeasures (jamming) systems.
edit Up and down converters
In agenda communications signals can be transmitted in baseband or passband. Typically, a down-converter is acclimated on the accepting end to transform the arresting from the passband aback to the baseband for added processing. The bounded oscillator abundance is \sqrt{2} e^{j2 \pi f_c t}, with fc getting the carrier frequency. This after-effects in a ascent of the accustomed arresting by \sqrt{2} and a appearance alive by fc to the left, so that the consistent arresting is amid in the baseband.
A radio abundance upconverter is a accessory that takes an ascribe of radio abundance activity of a specific abundance ambit and outputs it on a college frequency. Likewise, downconverters yield an ascribe abundance and abate it to a lower achievement frequency. Both converters are frequently acclimated in transverters and agenda communications. Upconverters accomplish this abundance about-face via heterodyning, the aforementioned assumption as avant-garde receivers and transmitters to account the frequency.
edit Analog cine recording
Many analog cine systems await on a downconverted blush subcarrier in adjustment to almanac blush advice in their bound bandwidth. These systems are referred to as "heterodyne systems" or "color-under systems". For instance, for NTSC video systems, the VHS (and S-VHS) recording arrangement converts the blush subcarrier from the NTSC accepted 3.58 MHz to ~629 kHz.6 PAL VHS blush subcarrier is analogously downconverted (but from 4.43 MHz). The now-obsolete 3/4" U-matic systems use a heterodyned ~688 kHz subcarrier for NTSC recordings (as does Sony's Betamax, which is at its base a 1/2" customer adaptation of U-matic), while PAL U-matic decks came in two mutually adverse varieties, with altered subcarrier frequencies, accepted as Hi-Band and Low-Band. Added cine formats with heterodyne blush systems cover Video-8 and Hi8.7
The heterodyne arrangement in these cases is acclimated to catechumen quadrature phase-encoded and amplitude articulate sine after-effects from the advertisement frequencies to frequencies recordable in beneath than 1 MHz bandwidth. On playback, the recorded blush advice is heterodyned aback to the accepted subcarrier frequencies for affectation on televisions and for altering with added accepted video equipment.
Some U-matic (3/4") decks affection 7-pin mini-DIN connectors to acquiesce dubbing of tapes after a heterodyne up-conversion and down-conversion, as do some automated VHS, S-VHS, and Hi8 recorders.
edit Up and down converters
In agenda communications signals can be transmitted in baseband or passband. Typically, a down-converter is acclimated on the accepting end to transform the arresting from the passband aback to the baseband for added processing. The bounded oscillator abundance is \sqrt{2} e^{j2 \pi f_c t}, with fc getting the carrier frequency. This after-effects in a ascent of the accustomed arresting by \sqrt{2} and a appearance alive by fc to the left, so that the consistent arresting is amid in the baseband.
A radio abundance upconverter is a accessory that takes an ascribe of radio abundance activity of a specific abundance ambit and outputs it on a college frequency. Likewise, downconverters yield an ascribe abundance and abate it to a lower achievement frequency. Both converters are frequently acclimated in transverters and agenda communications. Upconverters accomplish this abundance about-face via heterodyning, the aforementioned assumption as avant-garde receivers and transmitters to account the frequency.
edit Analog cine recording
Many analog cine systems await on a downconverted blush subcarrier in adjustment to almanac blush advice in their bound bandwidth. These systems are referred to as "heterodyne systems" or "color-under systems". For instance, for NTSC video systems, the VHS (and S-VHS) recording arrangement converts the blush subcarrier from the NTSC accepted 3.58 MHz to ~629 kHz.6 PAL VHS blush subcarrier is analogously downconverted (but from 4.43 MHz). The now-obsolete 3/4" U-matic systems use a heterodyned ~688 kHz subcarrier for NTSC recordings (as does Sony's Betamax, which is at its base a 1/2" customer adaptation of U-matic), while PAL U-matic decks came in two mutually adverse varieties, with altered subcarrier frequencies, accepted as Hi-Band and Low-Band. Added cine formats with heterodyne blush systems cover Video-8 and Hi8.7
The heterodyne arrangement in these cases is acclimated to catechumen quadrature phase-encoded and amplitude articulate sine after-effects from the advertisement frequencies to frequencies recordable in beneath than 1 MHz bandwidth. On playback, the recorded blush advice is heterodyned aback to the accepted subcarrier frequencies for affectation on televisions and for altering with added accepted video equipment.
Some U-matic (3/4") decks affection 7-pin mini-DIN connectors to acquiesce dubbing of tapes after a heterodyne up-conversion and down-conversion, as do some automated VHS, S-VHS, and Hi8 recorders.
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