Conversions

Conversions Introduction o    Information  must  be  transformed  into  signals  before  it  can  be  transported  across  the communication media o    How info is transformed depends on its original format and on the format used by the communication device o    If  you  want  to  send  a  letter  by  a  smoke  signal,  you  need  to  know  which  smoke patterns make which words in your message before building the fire o    Words   are   the   Information   and   the   puffs   of   smoke   are   representation   of   that information Introduction to the type of Conversions o    Data stored in the computer is in the form of 0's and 1's. To be carried from one place to the other, data is usually converted to digital signals o    This is called "Digital-to-Digital Conversion" or "Encoding digital data into digital signals" o    Sometimes we need to convert an analog signal to the digital signal o    For Example, conversion of  Telephone conversation to digital signal for a no. of different reasons such as to decrease the effect of noise o    This  is  called  "Analog-to-Digital  Conversion"  or  "Digitizing  an  Analog Signal" o    We  might  want  to  send  a  digital  signal  coming  out  of  computer  through  a medium designed for analog signals o    For example, To send data from one place to the other using a Telephone line o    This  is  called  "Digital-to-Analog  Conversion"  or  "Modulating  a  digital Signal" o    Often an analog signal is sent over long distances using analog media o    For Example, voice or music from a radio station which is an analog signal is transmitted  through  the  air,  however  the  frequency  of  voice  or  music  is  not suitable for this kind of Tx. o    The signal should be carried by a higher frequency signal o    This  is  called  "Analog-to-Analog  Conversion"  or  "Modulating  an  analog Signal"