QPSK symbol design shown graphically

The mapping between the symbol constellation points for various values of I and Q is described by a set of waveforms. In QPSK there are 4 symbols, labeled 11, 01, 10, 00. So each symbol conveys two bits. These symbols may be coded in a number of ways. A set of graphical displays show one way of doing this. The symbols themselves are also composed of waveforms with differing phases. These waveforms are used to build the composite QPSK signal. This document should be read in conjunction with an earlier brief paper on QPSK. (http://www.signalpro.biz/wordpress/?p=707)

This paper is an attempt to explain how the last line of the graphical QPSK signal waveform was constructed. In that construct two cycles of each symbol waveform were used. Note that negative values are simply drawn by inverting the symbol waveform.

Please visit the Signal Processing Group Inc., website and choose the complimentary items link. The files can be accessed from there.

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