Method and circuit arrangement for demodulation of a quadrature amplitude-or phase-modulated signal

摘要

For digital demodulation of a quadrature amplitude- or phase-modulated signal (xE(t)), this is sampled with a sampling frequency fs and A/D converted, which has the relationship 1 $f_s=\frac{4·f_0}{1+2·\mathrm{lambda}}$ with the carrier frequency f0, whereby lambda is a whole number greater than or equal to zero. The multiplications of the sampled and A/D converted quadrature amplitude- or phase-modulated signal usually necessary for demodulation, with the signal 2 $\cos \left(2·\mathrm{pi}·\frac{f_0}{f_s}·k\right)$ and the signal 3 $\sin \left(2·\mathrm{pi}·\frac{f_0}{f_s}·k\right)$ can be easily performed, whereby the individual sample values of the quadrature amplitude- or phase-modulated signal are multiplied by the value -1, 0 or 1.