Algorithms & Methods

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

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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

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

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

Innovation: Multipath Minimization Method

July 1, 2011By
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Mitigation Through Adaptive Filtering for Machine Automation Applications
Multipath is real and omnipresent, a detriment when GPS is used for positioning, navigation, and timing. The authors look at a technique to reduce multipath by using a pair of antennas on a moving vehicle together with a sophisticated mathematical model. This reduces the level of multipath on carrier-phase observations and thereby improves the accuracy of the vehicle’s position. read more

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Innovation: Doppler-Aided Positioning

May 1, 2011By
Figure 1. Satellite tracking and carrier-phase anomaly summary during the observation time-span. These data were collected in a dense urban environment in both static and kinematic mode. The superimposed red-points show epochs where carrier-phase observables are either missing or contaminated with cycle slips, loss of locks, and/or other measurement anomalies.

Improving Single-Frequency RTK in the Urban Enviornment
A look at how Doppler measurements can be used to smooth noisy code-based pseudoranges to improve the precision of autonomous positioning as well as to improve the availability of single-frequency real-time kinematic positioning, especially in urban environments. read more

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Innovation: Accuracy versus Precision

May 1, 2010By
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A Primer on GPS Truth
True to its word origins, accuracy demands careful and thoughtful work. This article provides a close look at the differences between the precision and accuracy of GPS-determined positions, and should alleviate the confusion between the terms — making abuse of the truth perhaps less likely in the business of GPS positioning. read more

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Innovation: Hybrid Positioning

March 1, 2010By
Figure 11. The electronic car used in the test.

A Prototype System for Navigation in GPS-Challenged Environments
A team of Australian and U.S. researchers have integrated a ground-based system with GPS and INS to create a hybrid system that provides precise and accurate position information continuously in a variety of environments where GPS alone comes up short. read more

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Multi-Sensor, Multi-Network Positioning

February 1, 2010By
FIGURE 1. Sample WLAN or Bluetooth fingerprint map, in meters.

Currently, no single technology, system, or sensor can provide a positioning solution any time, anywhere. The key is to utilize multiple technologies. We are now exploring a multi-sensor multi-network (MSMN) approach for a seamless indoor-outdoor solution. Its hardware platform is described in the previous article. The digital signal processor (DSP) is embedded in the GPS module. All sensors are integrated to the DSP that hosts core software for real-time sensor data acquisition and real-time processing to estimate user location. A smartphone handset provides wireless network measurements. read more

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