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TRANSMISSION Telecommunication tutorials



  • In HDX [Half Duplex] transmission, data travels in either direction but not in both the direction at a same time.

  • Although half duplex transmission can be used to send data in either direction, only one transmission occur at a time (but not simultaneously).

  • Typically, once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying (antennas are of trans-receiver type in these devices, so as to transmit and receive the signal as well).

  • An example of a half-duplex system is a two-party system such as a walkie-talkie, wherein one must use "Over" or another previously designated command to indicate the end of transmission, and ensure that only one party transmits at a time, because both parties transmit and receive on the same frequency.



[FDX] Full Duplex Transmission

  • Here data can travel in both directions simultaneously.

  • It has big advantage over half duplex where transmission can occur simultaneously in both directions.

  • It is important to note that to have full duplex transmission [NIC] Network Interface Card, Hub or Switch and other equipment must support it.

  • A full-duplex (FDX), or sometimes double-duplex system, allows communication in both directions, and, unlike half-duplex, allows this to happen simultaneously.

  • Land-line telephone and Mobile networks are full-duplex, since they allow both callers to speak and be heard at the same time, the transition from four to two wires being achieved by a Hybrid coil.

  • A good analogy for a full-duplex system would be a two-lane road with one lane for each direction



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