to the separate antennas a 1 to a n a common clock 154 usually of the receiver 152 is used as a reference to process carrier signal information from the antennas a 1 to a n to thereby enable differential carrier phase gps position detection each of the antennas a i to a n connects to the receiver 152 via a respective antenna adapter module 110 1 to 110 n in this particular embodiment these adapter modules 110 1 to 110 n have separate down converters 112 1 to 112 n that down convert the radio frequency rf carrier signals to an intermediate frequency signal if this down conversion can be accomplished for example via low side mixing with the common clock signal clk 153 from the clock 154 of the receiver 152 in more detail in one embodiment the down converters 112 1 to 112 n synthesize a lo signal preferably from the clock signal clk 153 and also preferably a multiple of the frequency of the clock the lo signal is used to heterodyne the carrier signals and obtain a lower frequency difference signal i e low side mixing specifically this lo signal is used to produce the intermediate frequency signal if it.