Abstract: A navigation satellite receiver that nulls interference and enhances satellite signals using differences in their spatial positions and that includes four antennas in a spatial array respectively connected to four amplitude and phase balanced receiver downconverter channels. Five satellite tracking channels are each connected to all four receiver channels and each includes despreaders and I/Q accumulators for early, late and punctual correlation. The despreader and accumulator combinations provide four-by-one vectors called aperture estimates. A code-gated maximum likelihood processor whitens these by multiplication with the mathematical inverse Cholesky factor of the interference data. This vector is generated in a millisecond block "k" and is multiplied by a similarly generated vector formed in a previous millisecond block "k-1". The magnitude of the resulting product is used for code tracking, and the phase of the result provides for carrier tracking.

Abstract: A rawinsonde system embodiment of the present invention includes a digital GPS snapshot buffer and a serial communications controller for transmitting message frames formed of a combination of digital GPS data from the snapshot buffer and digitized hardwired meteorological data input from a humidity-temperature-pressure instrument. The message frames are telemetered at a relatively low rate over a meteorological radio band to a ground station. Substantially all of the conventional GPS digital signal processing is performed by the ground station, including carrier recovery, PRN code locking, pseudo-range extraction, ephemeris data extraction, almanac collection, satellite selection, navigation solution calculation and differential corrections. Ground processing further includes Kalman filter wind velocity calculation.