it takes the digital signal then make processing on the signal to make it ready to be modulated
(modulation mean that we raise the frequency of signal to be suitable for transmission)
then the transmiter transmite it .
we make this line and channel coding in order to speading the bit rate of tranmitter and for small secure and for eleminating DC component of the signal if the signal has it (ex: three ones and two zeros have DC component)
and ather useful applications in transmition i don't remember it right now
thx Tom
hi if you r interested in vlsi project then there r lots of project which i had made including digital thermometer ..if you r from india then i can help you or go to link h**p://www.geocities.com/deb_mallik/cpld for more details or contact me at deb_mallik@yahoo.com
i can suggest you a project for digital thermometer using cpld ..you have to design pcb for the same ...code in vhdl ..and programmer to program in cpld.