201209 September/October 2012 Archives - Page 2 of 2 - Inside GNSS

201209 September/October 2012

September 3, 2012

Vector Delay Lock Loops

Equations 1 – 4

GNSS receivers determine their position and clock bias by measuring the arrival times of satellite signals. Delay lock loops (DLLs) are used in traditional receivers to measure the arrival times of the signals.

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By Inside GNSS

GPS Civil Funding

The Federal Aviation Administration (FAA) has told those awaiting their slice of the GPS civil program budget that the funds are on the way.

The money, which is supposed to support that portion of the GPS program springing from the needs of civilian users, has been held up for months. In fact, as of late August — with less than 40 days left to go in the fiscal year — the money had not been transferred to either the military’s GPS Directorate or the National Coordination Office (NCO) for Space-Based Positioning, Navigation, and Timing (PNT).

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By Dee Ann Divis

Improving GNSS Attitude Determination

This article describes an integration of a single-frequency GNSS, two-antenna heading system with low-cost inertial and magnetic field sensors in order to improve the availability and reliability of pure GNSS attitude determination. This method calculates a redundant attitude solution in an error-state Kalman filter using different sensor setups. As a result, the process of carrier phase ambiguity resolution accelerates.

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By Inside GNSS

Spoofs, Proofs & Jamming

TABLE 1. Spoofer antenna requirements for various hardened GPS signal types

“Here is Edward Bear, coming downstairs now, bump, bump, bump, on the back of his head, behind Christopher Robin. It is, as far as he knows, the only way of coming downstairs, but sometimes he feels that there really is another way, if only he could stop bumping for a moment and think of it. And then he feels that perhaps there isn’t.”
– A.A. Milne, Winnie-the-Pooh

Is our faith in the integrity and infallibility of the Global Positioning System misplaced or, perhaps, insufficiently grounded?

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By Inside GNSS

PNT Advisory Board Seeks Details on Economic Benefits of GPS

To help counter pressures from federal budget cutters and wireless advocates searching for more broadband spectrum, the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board is crafting a study documenting the economic benefits of GPS.

“We have a new assignment . . . to discover and disclose the economic contributions of the Global Positioning System,” Chairman Jim Schlesinger told the board at an August 15, 1012 meeting of the advisory board.

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By Dee Ann Divis