Title:
RADIO COMMUNICATION EQUIPMENT USING ORTHOGONAL MODULATION DEMODULATION CIRCUIT
Document Type and Number:
Japanese Patent JP3125717
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain a radio communication equipment using an orthogonal modulation demodulation circuit by which fluctuation in DC offset error is more accurately corrected.
SOLUTION: An orthogonal demodulation circuit 3 receives a QPSK signal and provides an output of an orthogonal base band signal, a base band signal generating circuit 8 receives transmission data and converts the data into two orthogonal analog base band signals, an orthogonal modulation circuit 10 receives the analog base band signal and a modulated frequency signal and provides an output of the QPSK signal, a changeover circuit 14 selects the analog base band signal or the QPSK signal, an A/D converter circuit 5 quantizes an output signal from the changeover circuit 14 and an offset error detection means 15 detects a DC offset error. Thus, even when the radio communication equipment is in operation, the DC offset error due to temperature fluctuation and power supply voltage fluctuation is reduced.
Inventors:
Junichi Ishii
Application Number:
JP14146497A
Publication Date:
January 22, 2001
Filing Date:
May 30, 1997
Export Citation:
Assignee:
NEC
International Classes:
H04L25/06; H04L27/20; H04L27/18; H04L27/22; H04L27/233; (IPC1-7): H04L27/20; H04L27/22
Domestic Patent References:
| JP1079693A | ||||
| JP6268553A | ||||
| JP389751A | ||||
| JP389750A |
Attorney, Agent or Firm:
Takao Maruyama