Error detecting method and device and signal demodulating method and device

An error detecting method for calculating a phase error in a PSK modulated signal having a modulation phase number changing in a time division manner wherein a received phase of the modulated signal is mapped as a point on a complex plane by allocating an inphase signal and a quadrature signal generated from the modulated signal as corresponding to values of the axis of abscissas and the axis of ordinates, and wherein said complex plane is considered divided into a plurality of signal areas based on said a predetermined maximum modulation phase number, the method comprising:

• calculating a phase error between the received phase of the modulated signal mapped on the complex plane and a reference phase in each of said plurality of signal areas;
• discriminating one signal area of said plurality of signal areas to which the received phase is mapped on the basis of the inphase signal and the quadrature signal;
• and
• selecting one from the plurality of phase errors calculated above, in accordance with the discriminated signal area.

An error detecting device for calculating a phase error in a PSK modulated signal having a predetermined modulation phase number, wherein a received phase of the modulated signal is mapped on a complex plane by allocating an inphase signal and a quadrature signal generated from the modulated signal as values of the axis of abscissas and the axis of ordinates, wherein said complex plane is considered divided into a plurality of signal areas based on said predetermined modulation phase number, and wherein said phase error is calculated between the received phase of the modulated signal thus mapped and a reference phase in each of said plurality of signal areas, the device comprising:

• signal converter for mapping the received phase of the modulated signal onto the complex plane by allocating the inphase signal and the quadrature signal as the values of the axis of abscissas and the axis of ordinates, respectively;
• calculator for calculating the phase error between the received phase of the modulated signal mapped by said signal converter and a reference phase in each of the plurality of signal areas, said phase error calculated as a perpendicular distance between the mapped position of the modulated signal and a reference straight line;
• calculator for discriminating which one signal area of said plurality of signal areas the received phase is mapped, based on the in-phase signal and the quadrature signal;
• and
• selector for selecting one from said plurality of calculated phase errors, based on said discriminated area.

A signal demodulating method comprising:

• receiving a PSK modulated signal having a predetermined modulation phase number;
• generating an inphase signal and a quadrature signal from the modulated signal;
• mapping a received phase of the modulated signal as a point on a complex plane divided into a plurality of signal areas corresponding to said modulation phase numbers, by allocating said inphase signal and said quadrature signal as values of the axis of abscissas and the axis of ordinates;
• calculating a plurality of phase errors for each received phase corresponding to a plurality of signal areas determined on said predetermined modulation phase number, each said phase error being a distance between the received phase of the modulated signal mapped as a point on the complex plane and a reference phase in each of said plurality of signal areas;
• discriminating one signal area to which the received phase is mapped, from the plurality of signal areas, on the basis of the inphase signal and the quadrature signal;
• selecting one from the plurality of phase errors calculated above, in accordance with the discriminating signal area;
• and
• synchronously demodulating said inphase signal and said quadrature signal by feeding back the selected phase error.

A signal demodulating method comprising:

• receiving a PSK modulated signal having different modulation phase numbers sequentially transmitted in a time division manner;
• generating an inphase signal and a quadrature signal from the modulated signal and detecting the modulation phase numbers sequentially changing in the time division manner;
• mapping a received phase of the modulated signal on a complex plane divided into a plurality of signal areas corresponding to said modulation phase number, by allocating said inphase signal and said quadrature signal as values of the axis of abscissas and the axis of ordinates;
• calculating a phase error between the received phase of the modulated signal mapped on the complex plane and a reference phase in each of a plurality of signal areas corresponding to a maximum modulation phase number, so as to obtain a plurality of phase errors;
• discriminating one signal area to which the received phase is mapped, from the plurality of signal areas corresponding to the modulation phase number, on the basis of the inphase signal and the quadrature signal;
• selecting one from the plurality of phase errors calculated above, in accordance with the discriminated signal area;
• and
• synchronously demodulating said inphase signal and said quadrature signal by feeding back the selected phase error.

A signal demodulating device comprising:

• a data receiving means for receiving a PSK modulated signal having a predetermined modulation phase number;
• a signal generating means for generating an inphase signal and a quadrature signal from the modulated signal received by said data receiving means;
• a signal mapping means for mapping a received phase on the modulated signal on a complex plane divided into a plurality of signal areas corresponding to said modulation phase number, by allocating said inphase signal and said quadrature signal as values of the axis of abscissas and the axis of ordinates;
• an error calculating means for calculating the phase error between the received phase of the modulated signal mapped by said signal mapping means and a reference phase in each of the plurality of signal areas, as a distance between the mapped position of the modulated signal and a reference straight line corresponding to each of said plurality of signal areas, so as to obtain a plurality of phase errors;
• an area discriminating means for discriminating one signal area to which the received phase is mapped, from the plurality of signal areas, on the basis of the inphase and the quadrature signal;
• an error selecting means for selecting one from the plurality of phase errors calculated by said error calculating means, in accordance with the signal area discriminated by said area discriminating means;
• and
• signal synchronizing means for synchronously demodulating said inphase signal and said quadrature signal by feeding back the selected phase error selected by said error selecting means.

A signal demodulating device comprising:

• a data receiver receiving a PSK modulated signal having different modulation phase numbers sequentially transmitted in a time division manner;
• a signal generator for generating an inphase signal and a quadrature signal from the modulated signal received by said data receiver;
• a phase number detector for detecting the modulation phase numbers sequentially changing in the time division manner, of the modulated signal received by said data receiver;
• a signal transformer for mapping a received phase of the modulated signal as a point on a complex plane divided into a plurality of signal areas corresponding to said modulation phase number, by allocating said inphase signal and said quadrature signal as values of the axis of abscissas and the axis of ordinates;
• an error calculator for calculating the phase error between the received phase of the modulated signal as mapped to be a point and a reference phase in each of a plurality of signal areas corresponding to a maximum modulation phase number, so as to obtain a plurality of phase errors;
• an area discriminator discriminating one signal area to which the received phase is mapped, from the plurality of signal areas corresponding to the modulation phase number of the modulated signal, on the basis of the inphase signal and the quadrature signal;
• an error selector selecting one from the plurality of phase errors calculated by said error calculator, in accordance with the discriminated signal area;
• and
• signal demodulator synchronously demodulating said inphase signal and said quadrature signal, based on feeding back the selected phase error.