Just a short time ago I read August’s Expert Advice by the Masked Engineer. I wish to lend full unflinching support to everything stated in that tract.

One advantage I have over that author: I’m self-employed — no one tells me to be quiet. At the same time I have bent over backwards to offer full cooperation for corrective efforts, and will continue to do that. What I offer is technical — not administrative — support. I’m not anyone’s boss.

As evidence of my complete concurrence, let me cite some manuscripts I wrote or coauthored during the past two decades, in reverse chronological order. Read the rest of this entry »

Assume that your mobile phone knows your mode of transportation (stationary, walking, riding a car, etc.) automatically. How could navigation algorithms take advantage of this information? Here’s a possible way this information can be used. When you are not moving at all, it would turn off the GPS receiver to save power, or apply Doppler positioning techniques when the standard positioning fails. When you pick up your phone and start walking, the navigator switches to Pedestrian Dead Reckoning (PDR) mode. In the PDR mode a direct view to satellites is not needed for updating the positioning as the sensor-based step counting and heading estimation takes care of position updates during the GPS signal outages. Finally, when you start your car, the phone detects “driving”-mode and allows the map-matching algorithm to fix the positions on a road network. It is clear that automatic recognition of motion mode would help the navigator in the difficult process of obtaining accurate PVT estimate from noisy observations. How would it be possible to do such recognition? In this article we will show how the data obtained from accelerometers can be used to distinguish between the relevant motion modes.

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Senlin Peng, Virginia Tech
Yanhong Kou, Beihang University
Jade Morton, Miami University

Following the successful launch of the GPS Block IIF SVN62 satellite on May 28, 2010, the Software GPS Receiver Laboratory at Miami University has been actively monitoring and analyzing the satellite signals.  This article presents the tracking results of 300 seconds of L1, L2C, and L5 signals collected on July 10, 2010 starting at 13:46:39.615 UTC time in Oxford, OH (39^o31’N, 84^o45’W).  The satellite elevation and azimuth were centered at approximately 31.5^o and 74.73^o during this short time interval.  The Transform-Domain Instrumentation Global Navigation Satellite System Receiver (TRIGR), a triple frequency RF front end and data collection system designed and built at the Ohio University Avionics Engineering Center, and a Novatel 703GGG antenna were used to collect the RF samples.  The receiver samples the L1, L2C, and L5 signals with 8-bit resolution at 56.32MHz frequency.  This article presents preliminary receiver code and carrier tracking results and analysis of the signal qualities. Read the rest of this entry »

Introduction

Today’s most common navigation solutions rely (either completely or partly) on Global Navigation Satellite Systems (GNSS). However, situations might easily arise where GNSS signal is either not available at all, or does not provide navigation solution with sufficient accuracy e.g., indoors, in narrow streets or gorges. No general solution has been found so far to GNSS-denied navigation, but algorithms which are situation and sensor dependent have been proposed and tested for both personal and vehicle navigation. Stereo cameras have been extensively used in the past 20 years by the computer vision community to determine visual odometry information. Integrating camera information with a complementary sensor like an IMU is a very complex task that has been addressed less frequently, even though it has a lot of advantages. Stereo cameras (much like our eyes) are used to estimate the 3D location of the objects surrounding the platform, and then the platform odometry information can be derived from those locations. Since LiDAR sensors are more accurate in providing 3D information about the scene, a natural extension of the stereo cameras based odometry would be a LiDAR based odometry. Read the rest of this entry »

Mark Smearcheck and Michael Veth
Air Force Institute of Technology

Introduction

Increasing availability and performance of state-of-the-art navigation sensors motivates the need for a highly accurate reference system commonly referred to as a time-space position information (TSPI) device. The Advanced Navigation Center at the Air Force Institute of Technology is working with the Air Force Flight Test Center to develop a next generation time-space position information (TSPI) system to be used for test and evaluation of modern navigation devices.

TSPI systems such as the GPS Aided Inertial Navigation Reference (GAINR) or Advanced Range Data System (ARDS) accompany navigation sensors during flight testing to collect the precise position, velocity, and attitude. Current GAINR TSPI performance levels include 1.0 m of position uncertainty, 0.1 m/s of velocity uncertainty, and 1.75 mrad of attitude uncertainty (Shockley & Ruff, 2008). Goal performance levels for next generation TSPI call for an order of magnitude improvement over current systems. Read the rest of this entry »

By A. Hauschild,  O. Montenbruck, P. Steigenberger, W. Cao, R.B. Langley, L. Urquhart, and M. Santos

Precise point positioning (PPP) has gained an increasing importance with the availability of precise orbit and clock information, for example from the International GNSS Service (IGS). Whereas PPP was limited in the past to post-processing due to the latency of the precise satellites ephemerides, the increasing number of real-time orbit and clock products opens a broad field of possibilities not only limited to positioning. With the increasing number of global navigation satellite systems, which are currently built-up as alternatives or augmentations to GPS, processing of mixed constellations will gain more importance for PPP.

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By Gabriele Giorgi, Peter J.G. Teunissen, Sandra Verhagen, and Peter J. Buist

Precise GNSS attitude determination is based on the GNSS carrier phase measurements. In order to benefit from these precise measurements, the unknown integer number of cycles needs to be resolved. For attitude determination applications, the process of integer ambiguity resolution largely benefits from the inclusion of a priori baseline length constraints. These constraints have been embedded into the core of the LAMBDA method, which has been extended as the constrained (C-) LAMBDA method. Its improved performance for reducing the Time-To-Fix has been tested with different real-world static and dynamic tests. Read the rest of this entry »

By Dean Bruckner, Frank van Graas and Trent Skidmore, Ohio University

Flight test results are presented for a single-frequency, airborne-only carrier phase position domain smoothing (CPDS) algorithm intended for use in differential or relative GPS architectures for aircraft precision approach and landing. Significant performance improvement is obtained compared to the conventional 100-s Local Area Augmentation System (LAAS) ground/air smoothing technique. Read the rest of this entry »

By C. Kessler, C. Ascher and Prof. G.F. Trommer
Institute of Systems Optimization, Karlsruhe Institute of Technology

The Institute of Systems Optimization (ITE) at the Karlsruhe Institute of Technology (KIT) is developing a Multi-Sensor Pedestrian Navigation System (MSPNS) for indoor applications with mapping capabilities based on a DUAL-IMU approach, laser measurements as well as Vision aiding. Different sensor configurations and aiding techniques are investigated to determine the optimal setup of our modular system for each particular application scenario.

Providing accurate positioning information in indoor scenarios is a crucial factor for first responders and firefighters. Both precise indoor localization and obtaining building information of previously unknown environments are essential for effective coordination. Therefore, a robust and accurate indoor MSPNS with mapping capabilities enables fast and successful missions and reduces risk for the deployed personnel.

However, the mentioned applications make high demands on navigational hard- and software. Read the rest of this entry »

By John Lavrakas, Advanced Research Corporation

The U.S. has provided the highly accurate and dependable GPS service to users worldwide for nearly two decades. In addition to this service, the U.S. has made corresponding commitments as to the types and quality of current and future GPS service through various documents, such as the GPS Standard Positioning Service Performance Standard, the Federal Radionavigation Plan, and numerous interface specifications. The question is, how is the U.S. doing in meeting these commitments?

The service provided by GPS has historically been excellent with each succeeding year demonstrating improvements in reduced range, position, and timing errors and better availability of signals.  Despite these improvements, however, signal and service aberrations have occurred, resulting in brief periods of poor performance for users.  Read the rest of this entry »