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Single Carrier QAM Modulator

  • Jouko Vankka
  • Kari Halonen
Chapter
Part of the The Springer International Series in Engineering and Computer Science book series (SECS, volume 614)

Abstract

The block diagram of the conventional QAM modulator is shown in Figure 2.4. The output of the QAM modulator is
$$ \begin{gathered} {I_{out}}\left( n \right) = I\left( n \right)\cos \left( {{\omega _{QDDS}}n} \right) + Q\left( n \right)\sin \left( {{\omega _{QDDS}}n} \right) \hfill \\ {Q_{out}}\left( n \right) = Q\left( n \right)\cos \left( {{\omega _{QDDS}}n} \right) - I\left( n \right)\sin \left( {{\omega _{QDDS}}n} \right), \hfill \\ \end{gathered} $$
(12.1)
where ωDDS is the output frequency of the quadrature direct digital synthesizer (QDDS), and I(n)> Q(n) are pulse shaped and interpolated quadrature data symbols [Tan95a]. In the base station, the multi-user I/Q data is combined and weighted and so the input of the I/Q branches is 12 bits in Table 12.1. The specifications are not so strict in Table 12.1 as in Table 11.1 because it is possible to use steep analog bandpass filters around the single carrier signal in Figure 11.2, and the adjacent channels’ power around the single carrier signal can be further reduced.

Keywords

Phase Accumulator Adjacent Channel Channel Power Symbol Constellation Configurable Logic Block 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Jouko Vankka
    • 1
  • Kari Halonen
    • 1
  1. 1.Helsinki University of TechnologyFinland

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