Title:
TRANSMISSION SYSTEM
Document Type and Number:
Japanese Patent JPH0229176
Kind Code:
A
Abstract:
PURPOSE: To eliminate the distortions which are caused in an in-phase channel demodulator by the signals included in a quadrature phase channel by supplying a quadrature phase carrier signal and an information signal to a double balanced modulator within the quadrature phase channel and also preparing an inverse Nyquist strobe filter. CONSTITUTION: A 90 deg. phase shifter 13 forms a carrier signal and a a carrier signal of a quadrature phase which are generated by an oscillator 11 and is connected to a double balanced modulator 15. A modulated quadrature phase carrier is sent to a filter circuit 20 having an inverse Nyquist transmission function and supplied to a BPF 25 contained in the filter 20. The BPF 25 supplies an output signal having the same amplitude/phase pair frequency response as an IF filter included in the corresponding receiver to a double balanced mixer 29 which uses the local oscillation frequency defined by doubling the quadrature phase carrier by a frequency multiplier 31. Then the modulated carrier is transmitted through an LPF 37 and turned into a mirror image of the signal of the output terminal of the BPF 25 after a signal of difference frequency is selected. Thus, the distortions of signals included in a quadrature phase channel can be prevented in a detection mode.
Inventors:
AREN ETSUCHI BOODOMAN
Application Number:
JP12163889A
Publication Date:
January 31, 1990
Filing Date:
May 17, 1989
Export Citation:
Assignee:
PHILIPS NV
International Classes:
H04N7/015; H04N7/04; H04N7/08; H04N7/081; (IPC1-7): H04N7/00; H04N7/08
Attorney, Agent or Firm:
Akihide Sugimura (1 outside)
Next Patent: JPH0229177