The System: Galileo in Its Glory

January 1, 2012By

  GALILEO PROTOFLIGHTMODEL satellite began transmitting E1 and E5 signals in early December. ESA reports them well within power and shape specifications, and suited for interoperability with GPS. The Galileo ProtoFlightModel (PFM) in-orbit validation (IOV) satellite GSAT0101 began transmitting E1 signals on December 10 using the E11 ranging code, and E5 signals early on December 14. Launched at the same... read more

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Innovation: Know Your Enemy

January 1, 2012By

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

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

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Expert Advice: Test-Based Civil Receiver Certification

December 1, 2011By

Disaster-preparedness plans recognize the individual’s role in his or her own survival. When storms approach, have water, food, and basic survival gear on hand. It takes time for help to arrive. The civil GPS industry faces an oncoming storm of interference, and the receiver is the first line of defense. As we integrate GPS into all facets of our lives and infrastructure, we become more subject to disruptions, both unintentional and intentional. Newark International Airport now sees several jamming events per day. In Taiwan, one airport experiences an average of 117 events per day! read more

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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

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Consumer GPS/GLONASS: Accuracy and Availability Trials of a One-Chip Receiver in Obstructed Environments

December 1, 2011By

A one-chip multiconstellation GNSS receiver, now in volume production, has been tested in severe urban environments to demonstrate the benefits of multiconstellation operation in a consumer receiver. Bringing combined GPS/GLONASS from a few tens of thousands of surveying receivers to many millions of consumer units, starting with satnav personal navigation devices in 2011, followed by OEM car systems and mobile phones, significant shifts the marketplace. The confidence of millions of units in use and on offer should encourage manufacturers of frequency-specific components, such as antennas and SAW filters, to enter volume mode in terms of size and price. read more

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Innovation: Digging into GPS Integrity

November 1, 2011By

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

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The System: Galileo IOV Satellites Now in Orbit

November 1, 2011By

The first two satellites for Europe’s Galileo global navigation satellite system were lofted into orbit October 21 by the first Russian Soyuz vehicle ever launched from Europe’s Spaceport in French Guiana in a milestone mission, reports the European Space Agency (ESA). The launch occurred one day after initially scheduled to resolve a problem with the ground-support fueling system. The Soyuz... read more

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