Algorithms & Methods

Innovation: Hunting for GNSS Echoes

November 1, 2013By
Figure 1. ARTEMISA simulation platform architecture.

Analysis of Signal Tracking Techniques for Multipath Mitigation
Researchers involved with ARTEMISA describe their efforts to generate synthetic multipath of GPS L1 and Galileo E1 signals and to test different signal tracking techniques in a simulated receiver to see which techniques best minimize the effects of multipath on positioning solutions. read more

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Innovation: Under Cover

September 1, 2013By
FIGURE 1. Artist’s impression of the synthetic-aperture GNSS system for surveying in a forest.

Synthetic-Aperture GNSS Signal Processing
We take a look at a novel GNSS signal-processing technique, which uses the principles of SAR to improve code and carrier-phase observations in degraded environments such as under forest canopy. The technique can simultaneously reject multipath signals while maximizing the direct line-of-sight signal power from a satellite. Along with a specially programmed software receiver, it uses either a single conventional antenna mounted, say, on a pedestrian’s backpack for GIS applications or a special rotating antenna for high-accuracy surveying. Want to learn more? Read on. read more

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GNSS PPP Workshop Early Registration Extended to May 3

April 25, 2013By

The International Association of Geodesy, Natural Resources Canada, the International GNSS Service, and York University will be hosting GNSS Precise Point Positioning: Reaching Full Potential in Ottawa, Canada, June 12-14, 2013. The primary objective of this workshop is to provide a forum for international experts from academia, government and industry to discuss PPP-related matters, including data processing, error modelling, data... read more

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Innovation: Getting at the Truth

January 1, 2013By
Inn-opener

A Civilian GPS Position Authentication System
When a GPS receiver reports its position to a monitoring center using a radio signal of some kind, how do we know that the receiver or its associated communications unit is telling the truth? It’s not that difficult to generate false position reports and mislead the monitoring center into believing the receiver is located elsewhere — unless an authentication procedure is used. In this month’s column, we look at the development of a clever system that uses the concept of supplicant and authenticator to assess the truthfulness of position reports. read more

This article is tagged with and posted in Algorithms & Methods, Design & Test, From the Magazine, Innovation

Innovation: Getting Along

November 1, 2012By
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Collaborative Navigation in Transitional Environments
In this month’s article, a team of researchers at The Ohio State University discusses a system under development for collaborative navigation in transitional environments — environments in which GPS alone is insufficient for continuous and accurate navigation. Their prototype system involves a land-based deployment vehicle and a human operator carrying a personal navigator sensor assembly, which initially navigate together before the personal navigator transitions to an indoor environment. This system will have multiple applications including helping first responders to emergencies. Read on. read more

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The Kinematic GPS Challenge: First Gravity Comparison Results

March 14, 2012By

By Theresa Diehl The National Geodetic Survey (NGS) has issued a “Kinematic GPS Challenge” to the community in support of NGS’ airborne gravity data collection program, called Gravity for the Redefinition of the American Vertical Datum (GRAV-D). The “Challenge” is meant to provide a unique benchmarking opportunity for the kinematic GPS community by making available two flights of data from... read more

Innovation: Filling in the Gaps

October 1, 2011By
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Improving Navigation Continuity Using Parallel Cascade Identification
To reliably navigate with fewer than four satellites, GPS pseudoranges needs to be augmented with measurements from other sensors, such as a reduced inertial sensor system or RISS. What is the best way to combine the RISS measurements with the GPS measurements? The classic approach is to integrate the measurements in a conventional tightly coupled Kalman filter. But in this month’s column, we look at how a mathematical procedure called parallel case identification can improve the Kalman filter’s job, when navigating with three, two, one, or even no GPS satellites. read more

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Innovation: The Right Attitude

September 1, 2011By
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Experimenting with GPS on Board High-Altitude Balloons
In this month’s column, we look at how a team of Dutch and Japanese researchers is using GPS to determine the attitude of a payload launched from a high-altitude balloon. read more