September 2010

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Boeing Company researchers collected real-time airborne position data during extensive flight tests on Boeing 747 and 777 aircraft using high-precision commercial satellite-based positioning systems rather than with traditional differential GPS techniques — and it worked.

Finnish researchers propose a new carrier-to-noise ratio (CNR) estimation method — an important metric in GNSS receiver operation — based on use of the level crossing rate of a receiver’s correlation function.

The second part of this article on simulators and simulator techniques and testing examines simulator designs, specification requirements for different types of equipment tests, and whether a specific simulator design is suitable for a particular test. See Part 1 in the July-August 2010 issue.

Distances between GNSS satellites and user equipment are measured from the antenna phase centers of the transmitting antenna. However, phase centers vary among types and generations of spacecraft and the calculation requires knowledge of orientation or attitude. A European Space Operations Center researcher  analyzed the initial performance of the first GPS Block IIF space vehicle and found some expected — and unexpected — results.

Frequency allocations suitable for GNSS services are getting crowded. System providers face an ever tougher job as they try to bring on new signals and services while maintaining RF compatibility and, in some cases, spectral separation. This two-part column explores the possibility, advantages, and disadvantages of using allocations in a portion of the S-band spectrum.

Release of an ICD would be good for both the Compass program and the community of GNSS receiver designers and end users who are looking for the additional signal resources that the Chinese system can bring.

What about fully digital state models for Kalman filters? Columnist Mark Petovello asks Letizia Lo Presti, Marco Rao and Simone Savasta for the answer.

GNSS data points and factoids to amuse and inform