FDM


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FDM

FDM

(1) (Fused Deposition Modeling) See 3D printing.

(2) (Frequency Division Multiplexing) Transmitting multiple data signals simultaneously over a single channel. Each data stream (text, voice, video, etc.) is modulated onto a carrier with a unique center frequency by the multiplexor and demodulated at the receving end (see modulation and carrier). FDM works in both wired and wireless applications (see FDMA).

It Started in the 1930s
In the 1930s, the telephone companies began to use FDM to combine multiple analog voice signals over one line to maximize efficiency of their long distance trunks. During the 1960s, FDM was replaced with TDM, its digital counterpart (see TDM and channel bank).

Cable TV companies use FDM to transmit hundreds of channels of analog and digital TV as well as Internet over a single coaxial cable. The set-top box or TV tuner locks onto a particular frequency (channel) and demodulates the carrier to derive the data for the TV screen. The cable modem both modulates and demodulates the appropriate carriers to provide bi-directional operation for Internet access. See FDMA, OFDM, circuit switching and WDM.

Analog FDM vs. Digital TDM
FDM separates signals by using different carrier frequencies, whereas TDM (time division multiplexing) interleaves signals as in the following illustrations.





References in periodicals archive ?
A few initial attempts of making polypropylene filaments and using them for FDM printing showed that problems with making filaments and extruding them with FDM printers could be rather easily addressed.
With an increasing number of women at FDM, our Women in IT campaign is going from strength to strength and over 50% of our management team is female.
Depending on the tool and part material, FDM tool life can range from 100 to 1000 parts.
Because FDM Vantage requires no special facilities of venting and involves no hazardous materials of by-products, Stratasys reports, the system is safe enough for use in an office environment.
Stratasys, which has addressed the issue to some extent with its FDM systems, has now targeted this segment of the design engineering community with its introduction of a fast single-material system that allows a designer to "print" concept iterations directly from the workstation on the design desk.
Gresham's Global Business Development Director, Bill Blythe adds, “We approached FDM to be a strategic implementation partner as the quality of their training is unrivalled and we believe their IT consultants will accelerate our capabilities, especially building on FDM's excellent credentials with major global banks.
FDM Group's CEO, Rod Flavell commented, “At FDM we support various charities throughout the world, because we believe in giving something back to society.
Existing FDM Vantage models can be upgraded to the S or SE.