Signal Processing

Galileo and Compass: A Tale of Also-Runnings

December 19, 2012By

Beating up the backstretch neck and neck, tied for third in the GNSS race, Galileo and Compass today offer some signals and some satellites to GNSS users — as long as those users are researchers. Galileo has more going for it in the way of signals, while Compass holds an edge in the number of satellites. Without an interface control... read more

Directions 2013: Doing More with Less to Advance GNSS

December 1, 2012By

The history of GNSS shows each year has always been more successful than the year prior, and in 2013 we expect the trend to continue. In the United States, the role of GPS will continue to expand, and the applications for our technology will reach sectors we never imagined. As our international partner countries continue to launch GNSS satellites, and user equipment develops further, our community will increase its globalization, and international cooperation will reach new heights. read more

Directions 2013: Dealing with Interference

December 1, 2012By

In my vision of the future of GNSS, I see a pressing need to manage radio-frequency spectrum more efficiently. This will drive the creation of official standards for GNSS receivers, and better design of those receivers with better filters at lower cost, to protect against out-of-band and near-band interference. This in turn will enable user to undertake widespread monitoring and reporting of in-band interference, and create the freedom for many technologies to explore wider and more productive use of all bands of the radio-frequency spectrum. read more

This article is tagged with , and posted in From the Magazine, GNSS Opinions, Signal Processing

Innovation: The Devil Is in the Details

July 1, 2012By
FIGURE 4. A CPSE observed on SVN48 (PRN07) on September 15, 2010, at 19:21:42 GPS Time. (Click to enlarge.)

Looking Closely at Received GPS Carrier Phase
The stability of a received GPS signal determines how well the receiver can track the signal and the accuracy of the positioning results it provides. While the satellites use a very stable oscillator and modulation system to generate their signals, just how stable are the resulting phase-modulated carriers? In particular, do received signals always conform to the published system specifications? In this month’s column we take a look at a specially designed receiver for analyzing GPS carrier phase and some of the interesting results that have been obtained. read more

This article is tagged with and posted in From the Magazine, GNSS, Innovation, Signal Processing

Reminder: Leap Second This Weekend

June 29, 2012By

News courtesy of CANSPACE Listserv. Likely none of us needs a reminder as the upcoming leap second has been all over the news outlets for the past few days. But just to provide the details again, read this article. Presumably, all GPS receiver manufacturers have checked to make sure their receivers will handle the leap second properly. However, at least... read more

This article is tagged with , and posted in Featured Stories, Signal Processing, Timing

Massive GPS Jamming Attack by North Korea

May 8, 2012By

Large coordinated cyber attacks from North Korea near its border with South Korea produced electronic jamming signals that affected GPS navigation for passenger aircraft, ships, and in-car navigation for roughly a week in late April and early May. To date, no accidents, casualties, or fatalities have been attributed to jammed navigation signals aboard 337 commercial flights in and out of South... read more

Innovation: Simulating GPS Signals

May 1, 2012By
FIGURE 3. Signal Architect simulation flow. (Click to enlarge.)

It Doesn't Have to Be Expensive
GNSS signal simulators can be expensive and beyond the limited budgets of many researchers. In this month’s column, we look at one company’s approach to providing GNSS signal simulation at a low cost — one that virtually any researcher can afford.GNSS signal simulators can be expensive and beyond the limited budgets of many researchers. In this month’s column, we look at one company’s approach to providing GNSS signal simulation at a low cost — one that virtually any researcher can afford. read more

Innovation: Ionospheric Scintillations

April 1, 2012By
FIGURE 1 Global occurrence characteristics of scintillation. (Figure courtesy of P. Kintner)

How Irregularities in Electron Density Perturb Satellite Navigation Systems
In this month’s column, the international Satellite-Based Augmentation Systems Ionospheric Working Group presents an abridged version of their recently completed white paper on the effect of ionospheric scintillations on GNSS and the associated augmentation systems. read more