Signal Processing

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

Patch Antennas for the New GNSS

February 1, 2012By

Small ceramic patch elements offer nearly perfect single-frequency receive characteristics and have become the standard for GPS L1 antennas. However, the new generation of GNSS receivers now being introduced track many satellites in multiple constellations. Are these narrow-band devices up to the task for wider bandwidths? read more

This article is tagged with , and posted in Signal Processing

Innovation: Know Your Enemy

January 1, 2012By
Inno-Opener

Signal Characteristics of Civil GPS Jammers
GPS jamming is a continuing threat. A detailed understanding of how the available jammers work is necessary to judge their effectiveness and limitations. A team of researchers from Cornell University and the University of Texas at Austin reports on their analyses of the signal properties of 18 commercially available GPS jammers. read more

Straight Talk on Anti-Spoofing: Securing the Future of PNT

January 1, 2012By
Spoofing

Disruption created by intentional generation of fake GPS signals could have serious economic consequences. This article discusses how typical civil GPS receivers respond to an advanced civil GPS spoofing attack, and four techniques to counter such attacks: spread-spectrum security codes, navigation message authentication, dual-receiver correlation of military signals, and vestigial signal defense. Unfortunately, any kind of anti-spoofing, however necessary, is a tough sell. read more

Low-Complexity Spoofing Mitigation

December 1, 2011By
Figure 3. Null steering toward the spoofer signals.

Most anti-spoofing techniques are computationally complicated or limited to a specific spoofing scenario. A new approach uses a two-antenna array to steer a null toward the direction of the spoofing signals, taking advantage of the spatial filtering and the periodicity of the authentic and spoofing signals. It requires neither antenna-array calibration nor a spoofing detection block, and can be employed as an inline anti-spoofing module at the input of conventional GPS receivers. read more

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

Innovation: Digging into GPS Integrity

November 1, 2011By
Inn-opener

Charting the Evolution of Signal-in-Space Performance by Data Mining 400,000,000 Navigation Messages
There are four important requirements of any navigation system: accuracy, availability, continuity, and integrity. In this month’s column we take a look at one particular aspect of GPS integrity: that of the signal in space and find out how trustworthy is the satellite ephemeris and clock information in the broadcast navigation message. read more

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