- 2068 Chaitra · 4 marks
Compare FDM, WDM and TDM
Short answer
FDM (analog) shares a medium by frequency bands; WDM (optical) does the same with wavelengths; TDM (digital) shares by time slots, one channel transmitting at a time. FDM and WDM send all channels simultaneously; TDM requires synchronization. FDM uses guard bands and modulators; WDM uses prisms/grating; TDM uses framing bits. FDM is for radio/cable, WDM for fibre, TDM for digital telephony.
Compare FDM, WDM and TDM.
| Point | FDM | WDM | TDM |
|---|---|---|---|
| Full form | Frequency division multiplexing | Wavelength division multiplexing | Time division multiplexing |
| Signal type | Analog | Optical (light) | Digital |
| Sharing by | Frequency bands | Light wavelengths | Time slots |
| Medium | Coax, radio, twisted pair | Optical fibre | Any (wire, fibre, radio) |
| Simultaneity | All channels at once | All channels at once | One channel at a time, in turn |
| Needs | Modulators, filters, guard bands | Prism / grating MUX and DEMUX | Synchronisation, framing bits |
| Interference | Crosstalk, intermodulation | Very low | Timing jitter, slot synchronisation |
| Examples | Radio/TV, cable TV | DWDM backbone | T1/E1, SONET |
WDM is essentially FDM applied to light, and TDM is the basis of digital telephony.
✓ Answer checked by Claude Sonnet 5.5
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