Multiple Receiver, Zero-Length Baseline Kinematic GPS Positioning Techniques for Airborne Gravity Measurement

Abstract

Despite advances in GPS receiver technology, undetected and uncorrected cycle slips remain a major problem which must be overcome before kinematic GPS interferometric positioning can be routinely used in airborne geophysical investigations. In an airborne scalar gravity survey, it is necessary to know the aircraft’ s geodetic position at a 1 Hz rate, or higher, to determine the vertical acceleration correction. An hour-long track, observing a minimum of four satellites in both the LI and L2 frequencies, yields 288,000 observations which must be checked for cycle slips. It has been suggested that the operation of multiple receivers (Brozena et al., 1989) would increase the likelihood that, for each observation epoch and for each satellite under observation, at least one receiver would maintain lock. Furthermore, if two or more receivers were operated from a single antenna, those observations would be stationary with respect to each other regardless of aircraft motion and could be examined using the double-difference techniques commonly used in static GPS work (Mader et al., 1991).