Pulse or digital communications – Receivers – Angle modulation
Patent
1997-02-14
2000-03-14
Bocure, Tesfaldet
Pulse or digital communications
Receivers
Angle modulation
375326, 375345, 329300, H04L 2714
Patent
active
060382686
ABSTRACT:
In this disclosure, a single combination of a multiplier and amplifier is utilized in a time-sharing manner for two-axis, in-phase an orthogonal phase components (I-axis and Q-axis components, respectively) so that the problem of a phase error relating to the use of the two separate circuits which are used for the respective two-axis components cannot be produced. Further, in this disclosure, this amplifier is constructed as a variable gain amplifier for the purpose of the application of AGC (automatic gain control) through the use of signal power obtained form the amplifier output, and any DC offset is automatically corrected using detecting and correcting means. After a process has been made in which the two-axis components are separated from the amplifier output, frequency detection is made by a frequency detector with linear frequency detection characteristics, which carries out a calculating operation of the separated two-axis components, and an output signal is provided by two-value judging the demodulated output thus obtained. Further, by carrying out comparison between the input and output of the two-value judging circuit, any center frequency error of the FSK signal is detected irrespective of code contents of the FSK signal, and the frequency of the local carrier for the direct conversion is controlled using the thus detected frequency error output.
REFERENCES:
patent: 5091921 (1992-02-01), Minami
patent: 5263194 (1993-11-01), Ragan
patent: 5414736 (1995-05-01), Hasegawa et al.
patent: 5446762 (1995-08-01), Ohba et al.
Bocure Tesfaldet
General Research of Electronics Inc.
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