Title:
DEMODULAITON APPARATUS OF DIGITAL SIGNAL MODULATED ACCORDING TO ALTERNATE MODULATION PATTERN TECHNIQUE
Document Type and Number:
Japanese Patent JPH0621989
Kind Code:
A
Abstract:
PURPOSE: To attain a simple and inexpensive configuration of the demodulator by demodulating a reception signal having a carrier frequency that is modulated by orthogonal phase modulation on two axes according to the π/4-QPSK digital modulation technology that uses two 4-phase state patterns shifted and selected alternately. CONSTITUTION: A received modulation signal 21 is given to multipliers 24, 25, where the signal is demodulated into a phase-demodulated signal 22 and an orthogonal-phase demodulated signal 23 by a local signal 26 with a carrier frequency whose phase is shifted by 90 deg. at a phase shifter 27. The signal 26 is supplied from an oscillator 28 that is voltage-controlled by a control signal 29 after passing through a low pass filter loop 29. Similarly the demodulation signals 22, 23 are filtered by low pass filters 30, 31. A phase control means 32 provides an estimate signal 35 to an alternate inverting means 34 that is controlled by a polarity inversion signal 48 and the means 34 that receives an estimate signal 35 denotes as E=(P).(Q)..(P+Q).(P-Q) by an estimating device 33 connected with the means 34.
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Inventors:
TEIERII PODORAKU
Application Number:
JP7682393A
Publication Date:
January 28, 1994
Filing Date:
April 02, 1993
Export Citation:
Assignee:
ALCATEL TELSPACE
International Classes:
H04J11/00; H04L27/22; H04L27/227; H04L27/00; (IPC1-7): H04L27/22; H04J11/00
Attorney, Agent or Firm:
Yoshio Kawaguchi (2 outside)
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