Patent ID: 6424683
Filing Date: 2002-07-23
Classification: H04L

Abstract:
A circuit for demodulating two-dimensional data symbols transmitted by a carrier-based data transmission, comprising:a tuner having a first intermediate frequency stage for converting a carrier frequency of a reception-side input signal containing the two-dimensional data symbols to a first intermediate frequency f1, a surface wave filter connected downstream of said first intermediate frequency stage, and a second intermediate frequency stage for converting the carrier frequency of the input signal to a second intermediate frequency f2 being lower than the first intermediate frequency f1 and connected downstream of said surface wave filter; and a quadrature demodulator connected downstream of said tuner and converting the input signal at the second carrier intermediate frequency f2 to a baseband and splitting the input signal into in-phase and quadrature components, said quadrature demodulator having an A/D converter with a prescribed sampling frequency fa and an anti-alias filter connected upstream of said A/D converter for removing interfering spectral components, the first intermediate frequency f1, the second intermediate frequency f2 and the sampling frequency fa being approximately defined by one of: f2=f1/5 and fa=4Â·f2; and f2=f1/5 and fa=4/5Â·f1.