{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

notes5 - ECE 562 Fall 2011 September 7 2011 Digital...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ECE 562 Fall 2011 September 7, 2011 Digital Modulation After possible source and error control encoding, we have a sequence { m n } of message symbols to be transmitted on the channel. The message symbols are assumed to come from a finite alphabet, say { 0 , 1 , . . . , M 1 } . In the simplest case of binary signaling, M = 2. Each symbol in the sequence is assigned to one of M waveforms { s 0 ( t ) , . . . , s M - 1 ( t ) } . Memoryless modulation versus modulation with memory. If the symbol to waveform mapping is fixed from one interval to the next, i.e., m mapsto→ s m ( t ), then the modulation is memoryless. If the mapping from symbol to waveform in the n -th symbol interval depends on previously transmitted symbols (or waveforms) then the modulation is said to have memory. For memoryless modulation, to send the sequence { m n } of symbols at the rate of 1 /T s symbols per second, we transmit the signal s ( t ) = summationdisplay n s m n ( t nT s ) . (1) Linear versus nonlinear modulation. A digital modulation scheme is said to be linear if we can write the mapping from the sequence of symbols { m n } to the transmitted signal s ( t ) as concatenation of a mapping from the sequence { m n } to a complex sequence { c n } , followed by a linear
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern