Patent ID: 7932859

Claim:
A method comprising: receiving a first signal from a satellite of a first satellite positioning system, the first signal having a first modulation sequence length, the first signal including a Galileo pilot signal including a 100 millisecond pseudorandom noise pilot signal sequence; receiving a second signal from a satellite of a second satellite positioning system, the second signal having a second modulation sequence length different from the first modulation sequence length, the second signal including a 6 second long Global Positioning System subframe, the Global Positioning System subframe including Global Positioning System pseudorandom noise sequences, each Global Positioning System pseudorandom noise sequence having a 1 millisecond length; determining a time offset between the first signal Galileo pilot signal from the satellite of the first satellite positioning system and the second signal Global Positioning System subframe from the satellite of the second satellite positioning system based on an estimated propagation delay of the first signal and the second signal; and establishing a position of a satellite positioning receiver based on the time offset wherein the method further comprises: estimating a propagation delay of the first signal Galileo pilot signal from the satellite of the first satellite positioning system; ascertaining a relative Galileo pilot signal transmit time for the first signal Galileo pilot signal from the satellite of the first satellite positioning system based on the propagation delay; deciding a search space for the second signal Global Positioning System subframe based on the Galileo pilot signal transmit time and the time offset between the first signal Galileo pilot signal and the second signal Global Positioning System subframe; and estimating a second satellite positioning system system time based on the search space, wherein establishing comprises establishing a position of a satellite positioning receiver based on the second satellite positioning system system time.