Existing digital radio systems, which use continuous phase frequency modulation with coherent detection, trade spectral efficiency for low bit error rate. In certain applications, such as satellite and mobile radio, they are subject to degradation due to fading and doppler shifts. This research will investigate the use of trellis coding of the signal space with CP-FM, using non-coherent, discriminator-based detection. This coding scheme will be applied for both symmetrical and asymmetrical signal constellations. System performance in the presence of Rician fading doppler effects will be investigated and compared to non-coherent detection of standard modulation schemes such as MSK, duo-binary, and TFM. Finally, an optimum modulation scheme will selected for a given code rate. A successful effort could result in more efficient communications systems that require less power for the same bit error rate, reduced weight, higher reliability, improved spectral efficiency, better doppler and fading performance, and lower costs.
