Non-coherently Detected Fqpsk: Rapid Synchronization and Compatibility with Pcm/fm Receivers#

A new class of non-coherent detection techniques for recently standardized Feher patented quadrature phase-shift keying (FQPSK) systems is proposed and studied by computer aided design/simulations and also verified by experimental hardware measurements. The theoretical concepts of the described non-coherent techniques are based on an interpretation of the instantaneous frequency deviation or phase transition characteristics of FQPSK-B modulated signal at the front end of the receiver. These are accomplished either by Limiter-Discriminator (LD) or by Limiter-Discriminator followed by Integrate-andDump (LD I&D) methods. It is shown that significant BER performance improvements can be obtained by increasing the received signal’s observation time over multiple symbols as well as by adopting trellis-demodulation. For example, our simulation results show that a BER=10 can be obtained for an Eb/N0=12.7 dB.