Patent ID: 7623871

Claim:
A method for determining a position estimate for a wireless terminal, comprising: obtaining a pseudo-range measurement for at least one transmitter which is included in a first position determination sub-system having synchronous transmitters; obtaining a pseudo-range measurement for at least one transmitter which is included in a second position determination sub-system; accessing a residual associated with each of the at least one transmitter included in the first sub-system, wherein the residual is based on a difference between a previous position estimate obtained at a first time using the first position determination sub-system and previous position estimate obtained at the first time using the second position determination sub-system; correcting the pseudo-range measurement for each of the at least one transmitter included in the first position determination sub-system based on the associated residual for the transmitter; and determining a position estimate for the terminal based on a plurality of measurements associated with a plurality of transmitters, wherein the plurality of measurements include at least one corrected pseudo-range measurement for the at least one transmitter included in the first position determination sub-system.