Pulse or digital communications – Receivers – Automatic frequency control
Patent
1998-02-05
2000-06-27
Chin, Stephen
Pulse or digital communications
Receivers
Automatic frequency control
375216, 375232, 375321, 331 2, H04L 2706
Patent
active
060815639
ABSTRACT:
A phase detection circuit detects a phase of a phase detection signal output from a complex multiplication circuit. A frequency error detection circuit detects a frequency error of a phase-detected signal, with the first frequency error detection characteristic in which a first frequency domain is defined as a detection range. An average circuit converts a signal having the detected frequency error into a signal having a second frequency error detection characteristic in which a second frequency domain other than the first frequency domain is defined as a detection range. After the average circuit calculates an average of frequency error signals for each period of time, it converts an average signal into a signal having the original first frequency error detection characteristic and outputs it to an AFC loop filter.
REFERENCES:
patent: 5418815 (1995-05-01), Ishikawa et al.
patent: 5440268 (1995-08-01), Taga et al.
patent: 5774789 (1998-06-01), Croft et al.
patent: 5832043 (1998-11-01), Eory
patent: 5909148 (1999-06-01), Tanaka
Mochizuki, N et al: "Performance of a QPSK Demodlator using a Double-Product Type AFC Circuit for Very-Low CNR Environments", Technical Report of IEICE, A-P97-14, SANE 97-5, SAT97-5 (1997-4).
Seki Takashi
Taga Noboru
Chin Stephen
Kabushiki Kaisha Toshiba
Liu Shuwang
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