US 5,241,567 AGranted

Circuit for demodulating PSK modulation signals

AssigneeJapan Radio Co., Ltd.

InventorYukihiro Shimakata

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Abstract

In a differential-detection demodulator circuit, a PSK modulated signal is compared with a locally oscillated signal to obtain a phase difference between the two signals, whereupon the phase difference is demodulated. A phase detector circuit of the digital type outputs the phase difference signal. The digital phase comparator circuit compares plural reference signals, which give predetermined delays to the locally oscillated signals having carrier frequencies, with the inputted modulated signals. Preferably, a pulse signal having a phase difference between the inputted modulated signal and the locally oscillated signal is produced, and the pulse width of this pulse signal is measured by a counter. By digitalizing the entire phase comparator, it is possible to realize demodulation with low electrical power consumption and simple circuit construction.

Claims5

Dependent claims

A demodulator circuit for demodulating a PSK modulated signal, comprising:

(a) a local oscillator means for outputting a locally oscillated signal having a frequency equal to a PSK modulated carrier frequency;
(b) a digital phase detector circuit for receiving both the modulated signal and the locally oscillated signal and comparing the two signals and outputting a phase data representative of a phase difference between the two signals;
(c) a 1-symbol delay circuit for delaying, by a time of 1 symbol, the phase data outputted from said phase detector circuit;
(d) a subtractor for receiving each phase data outputted from said phase detector circuit and said 1-symbol delay circuit and obtaining a change of the phase data during the time of 1-symbol and outputting the phase data as a phase difference signal;
and
(e) a decision means for making a decision on a value of demodulation data based on the phase difference signal outputted from the subtractor.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/724,184Filed 1 Jul 1991
Priority: JP 2-1787445 Jul 1990
Granted: 31 Aug 1993
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H04L 27/2332
Using non-coherent demodulation: using a non-coherent carrier
H03D 13/001
Circuits for comparing the phase or frequency of two mutually-independent oscillations: in which a pulse counter is used followed by a conversion…
H04L 27/2337
Using temporal properties of the received signal: using digital techniques to measure the time between zero-crossings
H04L 2027/003
Correction of carrier offset: at baseband only