METHOD IN DIGITAL QUADRATURE MODULATOR AND DEMODULATOR, AND DIGITAL QUADRATURE MODULATOR AND DEMODULATOR

摘要

The invention relates to a method for measuring imperfections in a digital quadrature modulator and demodulator operation, and to a digital quadrature modulator and quadrature demodulator. The modulator of the invention comprises means (11) for modulating quadrature-phase I and Q input signals to generate an output signal comprising quadrature-phase I and Q components; means (12) for taking momentary amplitude samples from the output signal of the modulator (11) at a rate based on a symbol clock (SCLK) of the modulator; means (13) for classifying a direction angle of the symbol to be modulated at a particular time into a particular direction angle sector; means (13) for linking the amplitude samples of the output signal to the direction angle sector corresponding to the symbol to be transmitted at a particular time; and means (13) for comparing the amplitudes of the samples belonging to each direction angle sector with other direction angle sectors or with an ideal value for determining the imperfections of the output signal of the modulator.