A method to improve navigation for a vehicle by utilizing detected multipath on the vehicle, the method comprising: receiving, with a monitor antenna, at least one first navigation signal transmitted from at least one satellite (140, 170), wherein the monitor antenna is located at a position on a front area of the vehicle; receiving, with a reference antenna, at least one second navigation signal transmitted from the at least one satellite (150, 180), wherein the reference antenna is located at a position on a back area of the vehicle; processing, with at least one monitor receiver, the at least one first navigation signal to obtain monitor measurement information; processing, with at least one reference receiver, the at least one second navigation signal to obtain reference measurement information; generating, with at least one processor, an estimate of a state of the reference antenna by using the monitor measurement information, the reference measurement information, and estimates of speed and direction of the vehicle, the state comprising at least one of a position of the vehicle, a velocity of the vehicle, and time offsets for the vehicle; using, with the at least one processor, the monitor measurement information to determine whether to isolate and exclude the reference measurement information obtained from the at least one second navigation signal from individual satellites by continuously measuring the distance between the reference antenna and previous locations of the monitor antenna using dead reckoning sensors of the vehicle speed and direction, and if the reference antenna is known to be far from any previous location of the monitor antenna, not significantly considering the monitor measurement information. receiving, with a monitor antenna, at least one first navigation signal transmitted from at least one satellite (140, 170), wherein the monitor antenna is located at a position on a front area of the vehicle; receiving, with a reference antenna, at least one second navigation signal transmitted from the at least one satellite (150, 180), wherein the reference antenna is located at a position on a back area of the vehicle; processing, with at least one monitor receiver, the at least one first navigation signal to obtain monitor measurement information; processing, with at least one reference receiver, the at least one second navigation signal to obtain reference measurement information; generating, with at least one processor, an estimate of a state of the reference antenna by using the monitor measurement information, the reference measurement information, and estimates of speed and direction of the vehicle, the state comprising at least one of a position of the vehicle, a velocity of the vehicle, and time offsets for the vehicle; using, with the at least one processor, the monitor measurement information to determine whether to isolate and exclude the reference measurement information obtained from the at least one second navigation signal from individual satellites by continuously measuring the distance between the reference antenna and previous locations of the monitor antenna using dead reckoning sensors of the vehicle speed and direction, and if the reference antenna is known to be far from any previous location of the monitor antenna, not significantly considering the monitor measurement information.