Disclosed is a method and apparatus for processing signals in a
satellite/laser positioning system capable of generating location
coordinates from received satellite signals and a received laser signal.
A height coordinate bias value is maintained by a filter processor during
periods when the laser signal is available. The height coordinate bias
value represents an estimated difference between a satellite signal
derived height coordinate and a laser signal derived height coordinate.
During periods when the laser signal is available, the laser signal
derived height coordinate is output. During periods when the laser signal
is not available, a corrected height coordinate value is generated by
applying the height coordinate bias value to the satellite signal derived
height coordinate.