Receiver for digital radio broadcasting via satellite

Quadrature Phase Shift Keying (QPSK) demodulators were investigated; a differential-coherent demodulator (with delay-line) for a 20.48 Mbit/sec and 118 MHz medium frequency was developed. A modified professional coherent demodulator (With Costas-loop carrier wave regaining) (CD), was compared with the DQPSK. At the cost of higher circuit complexity and more adjustings, the CD shows better performances; both demodulators show deviation values 2dB. Applied bit error detection and correction methods were investigated and decoding tables were developed. In cases of high system reserves (e.g., central antenna installations of TV-receiver installations) the cheaper DQPSK is recommended. A prefabricated delay-line (and medium frequency filter) in surface acoustic wave technique is recommended to avoid complicated adjusting procedures.