A method of providing frame synchronization for GPS signals can include performing coherent bit extraction on the GPS bits and then performing coherent frame boundary detection based on the bits of the coherent bit extraction. Concurrently, differential bit extraction on the GPS bits and differential frame boundary detection based on bits of the differential bit extraction can be performed. Whichever of the coherent frame boundary detection and the differential frame boundary detection first finds a frame boundary, then that frame boundary is used for the frame synchronization. A method of providing string synchronization for GLONASS signals includes performing coherent and differential bit extraction on the GLONASS bits.