week 4: DATA C0MMUNICATI0N

Data c0mmunicati0n is ability t0 transmit inf0rmati0n is very imp0rtant f0r current s0ceity including g0vernment agency,business pe0ple 0r even pers0nal needs by individuals. Data c0mmunicati0n may help people t0 give 0r get the inf0rmati0n even they are stayed near 0r far away and make easier t0 c0mmunicate each 0ther.

Data c0mmunicati0n can be divided by tw0 types 0f signal; anal0gue and digital signal.

ANAL0GUE SIGNAL

1.       1.   Anal0gue signal is like a human v0ice. It is f0rmed by c0ntinu0sly varying v0ltage levels that create a wave that can be grasped by an anal0gue transmitter like MICR0PH0NE.

       2.   This anal0gue signal features inv0lves 2 parameter;

a.       Frequency- number 0f c0mplete wave’s cycles. It is measured in Hertz (Hz) [cycle per sec0nd].

b.      Amplitude- wave’s height that measured in v0ltan (V) 0r decibel (dB).

DIGITAL SIGNAL

  

   1.Transmissi0n 0f binary electrical 0r light pulses that 0nly have tw0 p0ssible state, 0 and 1 [the language 0f c0mputer]

  2. Digital signal need to be change int0 anal0gue signal t0 be transmitted PSTN lines .

   3. The pr0cess 0f changing anal0gue t0 digital signal = m0dulati0n

   4. The pr0cess 0f changing back t0 anal0gue f0rm = dem0dulati0n

   5. M0Dem is the hardware that used in c0mputer t0 d0 this pr0cess.

An0ther that, data c0mmunicati0n als0 has data transmissi0n m0de. The data transmiss0n m0de divided by 2 categ0ries; parallel and serial transmissi0n.

1.       Parallel transmissi0n that a gr0up 0f bits is transmitted simultane0usly by using a separate line f0r each bit.

2.       Serial transmissi0n transmit all the bits 0ne after an0ther 0n a single line. This transmissi0n style is a bit sl0wer c0mpared t0 parallel transmissi0n; h0wever it is best suit data c0mmunicati0n needs t0 transmit data in a l0ng distance area.

  3.       Divided by 2 serial; Synchr0n0us and Asynchr0n0us transmissi0n.

a.       Synchr0n0us transmissi0n

               i.      A large gr0up 0f data is transmitted in bl0cks called by a FRAME

b.      Asynchr0n0us transmissi0n

             i.     Used when the bits are divided int0 small gr0ups (bytes) and sent independently.

         ii.      The gr0ups 0f bits can be sent at any time and the receiver never kn0ws when they will arrive, f0r example, a keyb0ard.

Data fl0w is 0ne 0f the data c0mmunicati0n. Data c0mmunicati0n between 2 pieces 0f equipment, the pr0cess 0f exchanging data can be d0ne in either three 0perati0n styles. The message s0urce will be called transmitter while the destinati0n where the message will be sent is called receiver t0 pr0vide easier understanding 0n h0w the data fl0w actually w0rk. The data fl0w are divided by 3; simplex, half-duplex and full-duplex

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1.       Simplex

a.       Data 0r inf0rmati0n is transmitted in 0ne directi0n 0nly.

b.      The r0le 0f the transmitter and receiver are FIXED.

c.       Example: radi0, televisi0n

    2.       Half-duplex

a.       Message can fl0w in 2 directi0n, but never at the same time.

b.      0ne stati0n transmits inf0rmati0n t0 an0ther stati0n with0ut any interupti0n.

c.       The 0ther stati0n will resp0nse after that transmissi0n has been c0mpleted.

d.      Example: walkie-talkie

       3.       Full-duplex

a.       B0th stati0n can transmit and receive simultine0usly.

Multiplexing is a set 0f technique that enable m0re than 0ne device t0 c0mbine and send their signals simultane0uslt thr0ugh a single data link at the same time.

C0axial cable 0r c0ax, has an inner c0nduct0r surr0unded by a flexible, tubular insulting layer, surr0unded by a tubular c0nducting shield. The term c0axial c0mes fr0m the inner c0nduct0r and the 0uter shield sharing the same ge0matric axis. C0axial cable is used as a transmissi0n line f0r radi0 frequency signals. Its applicati0n include feedlines c0nnecting radi0 transmitters and receivers with their antennas, c0mputer netw0rk (internet) c0nnecti0ns, and distributing cable televisi0n signals.