Innovation: Navigation from LEO

Current Capability and Future Promise
GPS signals are so weak, they cannot be used reliably where they are obstructed such as indoors or in concrete canyons. But if the satellites were much closer, their signals would be much stronger. The low Earth orbit Iridium constellation is already orbiting, and providing a PNT service. This month we learn about its current capability and future promise. read more

Innovation: Checking the accuracy of an inertial-based pedestrian navigation system with a drone

I’m Walking Here!
An ingenious navigation technique makes use of how the human body works to develop an accurate pedestrian navigation system — one whose accuracy has been checked using drone imagery. read more

Innovation: Laser ranging to GNSS satellites

May 24, 2017By

In this article, author Urs Hugentobler looks at the history of laser ranging to navigation satellites, how that ranging has improved the accuracy of the orbits of those satellites, and what the future portends for this important contribution to space geodesy. read more

Innovation: Orbit determination of LEO satellites with real-time corrections

Precision on board
Described are the results of realistic simulations carried out to precisely position a low-Earth-orbit satellite using a source of real-time GPS corrections actually transmitted by a network of geostationary satellites. Even accounting for data outages, 3D positioning accuracies better than a decimeter have been obtained. Precision on board? Not right now but likely coming real soon. read more

Innovation: Position estimation using non-line-of-sight GPS signals

March 15, 2017By and

Reflected Blessings.
A technique developed by researchers at the University of Illinois at Urbana-Champaign distinguishes a reflected non-line-of-sight (NLOS) signal of a particular satellite from the LOS signal and characterizes the NLOS signal as coming from a virtual mirror-image satellite in the direction of the signal reflection point. By using information on the position and orientation of the reflector, the NLOS signal can be treated as an additional LOS signal. read more

Innovation: Mitigating interference with a dual-polarized antenna array in a real environment

Double Take
A diversely polarized antenna array combines signal processing in the spatial and polarization domains for significant improvement in receiver robustness against interference. The C/N0 of line-of-sight components is improved since the receiver can use the power present in the left-hand circularly polarized channels, and also interference mitigation improves. read more

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Innovation: Correlator beamforming for low-cost multipath mitigation

January 13, 2017By , and

GNSS Pest Control
A new solution for GNSS multipath employs a multi-element antenna with RF signal switching and a single front end to reduce complexity, power consumption and cost. Correlator beamforming, initially used in the 2.4 GHz frequency band where it has proven effective at mitigating multipath in heavy industrial environments, has been successfully adapted for GNSS use. read more

Innovation: Precise positioning using raw GPS measurements from Android smartphones

November 7, 2016By and

Precision GNSS for everyone
In this month’s column, we take a look at some initial efforts to independently process smartphone measurements. How good are the results? Read on. read more

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