Receiver Design

Spoofing Detection and Mitigation with a Moving Handheld Receiver

September 1, 2010By

A single spoofing source has a different spatial signal distribution from the authentic GPS signal. An antenna array can estimate the spatial distribution of the received signal and thus discriminate the spoofing signal from the authentic one. Moving a handheld receiver with a single antenna during signal capture snapshots produces a form of a synthetic array, highly effective in discriminating spoofing signals sourced from a point-source jammer. read more

This article is tagged with , , and posted in Receiver Design

Part 2: The Origins of GPS, Fighting to Survive

June 1, 2010By
At the JPO. Frank Butterfield of Aerospace, Col. Parkinson, and Cdr. Bill Huston, deputy JPO director from the U.S. Navy,
in the early 1970s. A model of a Phase I GPS satellite stands on the table between the latter two.

GPS Phase I program approval meant that the real work could begin. The conclusion of a two-part history, told by the people who made it. read more

Part 1: The Origins of GPS, and the Pioneers Who Launched the System

May 1, 2010By
Mathematician Bill Guier (l) and physicist George Weiffenbach (r), told APL Research Center director Frank T. McClure (c), about their success using Doppler tracking for satellites. “McClure’s brain started going into fast forward,” remembered John Dassoulas. “Knowing the navigational challenges the U.S. Navy faced, McClure said, ‘Well, if you can find out where the satellite is, you ought to be able to turn that problem upside down and find out where you are.’ “

The original system study, the key innovations, and the forgotten heroes of the world’s first — and still greatest — global navigation satellite system. True history, told by the people who made it. Part One of a Two-Part Special Feature. read more

Testing Software Receivers

December 1, 2009By

To meet the challenges inherent in producing a low-cost, highly CPU-efficient software receiver, the multiple offset post-processing method leverages the unique features of software GNSS receivers to greatly improve the coverage and statistical validity of receiver testing compared to traditional, hardware-based testing setups, in some cases by an order of magnitude or more. read more

This article is tagged with and posted in LBS/Wireless, Mobile Devices, Receiver Design

The Smartphone Revolution

December 1, 2009By

Seven technologies put GPS in mobile phones around the world. Here is the how and why of location’s entry into modern consumer mobile communications. read more

This article is tagged with , and posted in LBS/Wireless, Mobile Devices, Receiver Design

Higher Timing Accuracy, Lower Cost

November 1, 2009By
AURORA BOREALIS seen from Churchill, Manitoba, Canada. Ionospheric scintillation research can benefit from this new method.

Inside a typical GNSS receiver, the estimate of the error in the local oscillator is formed as a component of the navigation solution, which is in turn based on the output of each satellite-tracking channel propagating its estimate of carrier and code measurements to a common future point. But this method limits the resolution with which the noise of the local oscillator can be quantified. To bypass this shortcoming requires a method of coherently gathering information about the phase change in the local oscillator across all available satellite signals: to use the same samples simultaneously for all satellites in view to estimate the center-point phase error common across the visible constellation. We explore how. read more

This article is tagged with and posted in Receiver Design, Simulators & Tools, Timing

Real-Time Software Receivers: Challenges, Status, Perspectives

September 1, 2009By
FIGURE 2. Single-instruction single-data versus single-instruction multiple-data.

By Marcel Baracchi-Frei, Grégoire Waelchli, Cyril Botteron, and Pierre-André Farine The idea of a software receiver is to replace the data processing implemented in hardware with software and to sample the analog input signal as close as possible to the antenna. Thus, the hardware is reduced to the minimum — antenna and analog-to-digital converters (ADCs) — while all the signal processing... read more

This article is tagged with and posted in GNSS, Receiver Design

Innovation: GNSS Radio (PDF)

May 1, 2006By

Innovation: GNSS Radio: A System Analysis and Algorithm Development Research Tool for PCs (PDF) By J.K. Ray, S.M. Deshpande, R.A. Nayak, and M.E. Cannon Published: May 2006 GPS World In this month’s column, a team of researchers from India and Canada describe a GNSS radio and how they have used it to develop and test algorithms for processing both legacy... read more

This article is tagged with and posted in Algorithms & Methods, Innovation, Receiver Design