A radio frequency signal is frequency-translated to form a complex first intermediate signal where a frequency corresponding to a GPS center frequency is at an intermediate frequency. In a multiplexing conversion unit a complex multiplexed conversion signal which assumes different conversion frequencies is derived from a clock signal where the frequency of the latter is divided alternately by one of two divisors in a divider circuit and further by two in a phase shifter. The conversion signal is mixed with the first intermediate signal in a conversion mixer to provide a multiplexed second intermediate signal where, depending in each case on the conversion frequency, a frequency corresponding to a GLONASS center frequency and a frequency corresponding to a BeiDou center frequency are alternately shifted close to the intermediate frequency. The first intermediate signal and the second intermediate signal are then processed in a baseband unit.