Digital modulation in ENG microwave
Earlier we discussed AM and FM, and as we saw, both are methods of transmitting information on a carrier wave radio signal. Both AM and FM are used in broadcasting radio and analogue TV. In the context of digital, a new method of modulation joins the fray – coded orthogonal frequency division multiplex (COFDM).
Like many of the subjects in this book, it is too complex a subject to cover in detail, so we will just look at the bare essentials.
For COFDM to work, it is necessary for the information signal to undergo a process known as compression, but as it is common to satellite communications, we will look at how compression works in more detail later. So for the time being, assume our digital signal ...