Homodyne receiver and process for direct conversion

Abstract

The invention pertains to a homodyne receiver and a process for direct conversion of angle-modulated carrier signals, especially those that have a d.c.-voltage component in the converted signal (IF). With many types of-modulation the (short-time) d.c. component of the conversion signal contains information about the modulating signal. Additional d.c. offsets are usually separated out by using a bandpass for the IF signal. In the process, however, the information-containing d.c. components of the converted signal are lost; as a result the demodulated signal is disturbed and in particular the distortion factor is raised. To avoid this the invention provides that the local oscillator for generating inphase and quadrature signals has a frequency offset from the carrier frequency of the receiver signal so that the frequency differential between carrier and frequency and oscillator frequency is in the transmission band of the bandpass used to suppress undesirable mixes, carrier reminders and d.c. offsets.

Dependencies are inferred from the claim text.