Frequency Division Multiplexing (AI Song)

#AIart #AImusic #sunoai #Net+ #studyguide [Intro] One medium, many signals — each one living in its own slice of the spectrum Frequency Division Multiplexing gives every channel its own frequency bedroom No time sharing, no taking turns — all channels transmit simultaneously FDM is the foundation of radio, cable TV, and telephone history [Chorus] Your own lane — a dedicated frequency band Each signal stays in its slice — that is the plan Guard bands keep the channels from bleeding into each other FDM lets every signal run without disturbing its brother Simultaneous transmission — all channels fire at once Your own lane — frequency division never fronts [Verse 1 — How FDM Works] The available bandwidth of the medium is divided into sub-bands Each sub-band is a channel — assigned to one signal and its demands The signal is modulated onto a carrier frequency inside its band AM, FM, or QAM modulation — the technique depends on what is planned A carrier wave is a pure sine wave at the center of the channel frequency The data signal modulates the carrier — changing its amplitude or frequency AM changes the amplitude — the height of the wave carries the information FM changes the frequency — the rate of oscillation is the modulation At the receiver a bandpass filter extracts one channel from the full spectrum It passes only the frequencies inside that channel's band — rejects the rest of them Demodulation strips the carrier away — leaving only the original signal clean Multiple receivers each tuned to a different channel — that is the FDM scheme [Chorus] Your own lane — a dedicated frequency band Each signal stays in its slice — that is the plan Guard bands keep the channels from bleeding into each other FDM lets every signal run without disturbing its brother Simultaneous transmission — all channels fire at once Your own lane — frequency division never fronts [Verse 2 — Guard Bands, Efficiency, and Real World Use] Guard bands are empty frequency gaps between adjacent channels on the spectrum They prevent interference from one channel bleeding into the next — a spectrum septum Without guard bands the edges of one channel overlap the next channel's band Intermodulation distortion corrupts both signals — guard bands take a stand Guard bands waste spectrum — the empty space carries no data at all The wider the guard band the cleaner the separation — but efficiency will fall OFDM solves this with mathematically orthogonal subcarriers tightly packed No guard band needed between subcarriers — spectrum efficiency is maxed Analog telephone used FDM to carry multiple calls on one wire in the past POTS multiplexed calls onto carrier systems — twelve calls per group held fast AM radio uses FDM — each station gets a 10 KHz channel in the AM band 530 KHz to 1700 KHz — hundreds of stations each with their own land FM radio uses FDM — each station gets 200 KHz of spectrum to broadcast 88 MHz to 108 MHz — stereo audio and RDS data riding the mast Cable television used analog FDM — each TV channel on a 6 MHz slice Channels 2 through 83 each modulated onto their carrier — wasn't that nice [Bridge — OFDM and WDM as FDM Variants] OFDM is Orthogonal Frequency Division Multiplexing — FDM evolved The orthogonality condition means subcarrier peaks align with neighbor nulls — problem solved Each subcarrier is spaced exactly one over the symbol duration apart in frequency The nulls of each subcarrier hit the peaks of its neighbors — no interference you see This allows subcarriers to overlap in frequency without interfering at all Spectral efficiency far exceeds classic FDM — a much tighter hall Wi-Fi 802.11a, g, n, ac, ax all use OFDM for the physical layer LTE and 5G NR use OFDM — every modern wireless standard is a player WDM is Wavelength Division Multiplexing — FDM applied to fiber optic light Each wavelength of light is a separate channel running through the same fiber tonight CWDM coarse WDM spaces wavelengths 20 nm apart — up to 18 channels wide DWDM dense WDM spaces wavelengths 0.8 nm apart — 80 or more channels inside Terabits per second on one strand of glass — WDM made it possible to ride [Chorus] Your own lane — a dedicated frequency band Each signal stays in its slice — that is the plan Guard bands keep the channels from bleeding into each other FDM lets every signal run without disturbing its brother Simultaneous transmission — all channels fire at once Your own lane — frequency division never fronts [Outro] FDM assigns each signal a permanent frequency lane of its own Guard bands separate the channels — spectrum efficiency is the tone OFDM packs subcarriers orthogonally — no guard band required WDM takes FDM to fiber — terabits per second admired