ON THE REPRESENTATION OF CPM SIGNALS BY LINEAR SUPERPOSITION OF IMPULSES IN THE BANDPASS DOMAIN

In the course of this paper, a novel signal generation concept for continuous phase modulations (CPM) with modulation index 1/2 based on real-valued impulses is presented. With this concept, bandpass CPM signals can be generated directly in one step instead of two consecutive steps, namely the generation of the complex envelope and the modulation of the carrier by the complex envelope, which are necessary in conventional signal generators. Mathematical expressions for both the real impulses and the bandpass CPM signals are derived and a simple modulator structure is discussed. Examples for the real-valued impulses are given. Among these are the well-known continuous phase modulation schemes of minimum shift keying (MSK), sinusoidal frequency shift keying (SFSK), and Gaussian minimum shift keying (GMSK). As an example, the validity of the novel signal generation concept will be shown for the latter CPM scheme.