Title :
A carrier recovery scheme for 4-CPFSK with h=1/4
Author :
Schoonees, J.A. ; Braun, R.M.
Author_Institution :
Dept. of Electr. Eng., Cape Town Univ., Rondebosch, South Africa
Abstract :
A carrier recovery scheme for 4-level CPFSK with h=1/4 is proposed. It is based on four frequency-switched Costas or in phase-quadrature (I-Q) loops, each synchronized on one of the signalling frequencies. The term “frequency-switched” refers to the way which one loop at a time is closed, depending on the data (frequency) estimate after decoding. From the I-Q loop´s viewpoint, the CPFSK signal contains the correct signaling frequency on average only a quarter of the time. For the rest of the time, the signal is tracked by the other loops. This is not to be confused with data-aided or decision-feedback synchronization. Each loop resembles the conventional QPSK Costas loop synchronizer, with additional circuitry to rotate the signal space. Simulation results are presented
Keywords :
demodulation; frequency shift keying; phase locked loops; synchronisation; 4-level CPFSK; QPSK Costas loop synchronizer; carrier recovery; data estimate; decoding; frequency estimate; frequency switched Costas loop; in phase-quadrature loops; signal space rotation; signalling frequencies; simulation results; Africa; Circuits; Cities and towns; Decoding; Frequency estimation; Frequency synchronization; Oscillators; Quadrature phase shift keying; Switches; Tracking loops;
Conference_Titel :
Communications and Signal Processing, 1993., Proceedings of the 1993 IEEE South African Symposium on
Conference_Location :
Jan Smuts Airport
Print_ISBN :
0-7803-1292-9
DOI :
10.1109/COMSIG.1993.365861
