Modulation and multiplexing

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Multiplexing vs. Modulation
Nelson Botero Giraldo
Facultad de Minas ,Universidad Nacional De Colombia Medellín

Abstract— this document, shows in an easy way, the differencebetween multiplexing and modulation, also describes several techniques used in each process. Keywords— FDM, TDM, CDM, WDM, ASK, FSK, PSK,

QAM, PAM, PCM, Multiplexing, Modulation. I. INTRODUCTIONIn Bit-Interleaved TDM, a single data bit from an I/O port is output to the aggregate channel. This is followed by a data bit from another I/O port (channel), and so on, and so on, with the processrepeating itself.

The information transmission process needs to be able to go faster or farther, as a response of this need; many different technologies have become more important dependingon the purpose of the network used. Below a brief description of the process and technique mentioned above.

Multiplexing is sending multiple signals or streams of information ona carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end.

Code division multiplexing (CDM) is a technique in whicheach channel transmits its bits as a coded channel-specific sequence of pulses. This coded transmission typically is accomplished by transmitting a unique timedependent series of short pulses, which areplaced within chip times within the larger bit time. All channels, each with a different code, can be transmitted on the same fibber and asynchronously demultiplexed. Other widely used multipleaccess techniques are Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA).

In a FDM, multiple channels are combined onto a single aggregate signal fortransmission. The channels are separated in the aggregate by their frequency. There are always some unused frequency spaces between channels, known as “”guard bands” these guard bands reduce the effects of...
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