Revision as of 08:32, 29 May 2025 edit Griotspeak (talk \| contribs) 2 edits m Carrier and message were accidentally swapped in this sentence. The carrier wave is usually a lower frequency than the message. (unless I'm misunderstanding what is being conveyed.) Tag: Reverted ← Previous edit		Revision as of 11:37, 29 May 2025 edit undo Griotspeak (talk \| contribs) 2 edits Undid revision 1292871707 by Griotspeak (talk) Tag: Undo Next edit →
Line 13: The process encodes information in form of the modulation or message signal onto a [[carrier signal]] to be transmitted.<ref>{{Cite web \|date=2014-10-22 \|title=How does modulation work? {{!}} Tait Radio Academy \|url=https://www.taitradioacademy.com/topic/how-does-modulation-work-1-1/ \|access-date=2024-06-17 \|website=Tait Radio Academy}}</ref> For example, the message signal might be an [[audio signal]] representing [[sound]] from a [[microphone]], a [[video signal]] representing moving images from a [[video camera]], or a [[digital signal]] representing a sequence of binary digits, a [[bitstream]] from a computer. This ~~message~~carrier ~~signal~~wave usually has a much higher [[frequency]] than the ~~carrier~~message signal does. This is because it is impractical to transmit signals with ~~lower~~low frequencies. Generally, receiving a [[radio wave]] requires a [[radio antenna]] with a length that is one-fourth of the wavelength of the transmitted wave.<ref>{{cite web \|url=https://www.wimo.com/en/faq/post/what-antenna-length-do-i-need-for-which-frequency \|title=General Antennas: What antenna length do I need for which frequency? \|first=Rodrigo "Rod" \|last=Herrera \|date=April 23, 2024 \|website=wimo.com \|access-date=June 19, 2024 \|lang=en}}</ref> For low frequency radio waves, wavelength is on the scale of kilometers and building such a large antenna is not practical. Another purpose of modulation is to transmit multiple [[Communication channel\|channels]] of information through a single [[transmission medium\|communication medium]], using [[frequency-division multiplexing]] (FDM). For example, in [[cable television]] (which uses FDM), many carrier signals, each modulated with a different [[television channel]], are transported through a single cable to customers. Since each carrier occupies a different frequency, the channels do not interfere with each other. At the destination end, the carrier signal is [[demodulation\|demodulated]] to extract the information bearing modulation signal.

Signal modulation: Difference between revisions