Magazine Section Archives - Page 48 of 66 - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

July 5, 2012

Single- versus Dual-Frequency Precise Point Positioning

Q: What are the tradeoffs between using L1-only and L1+L2 for PPP?

A: Precise point positioning (PPP) is a technique that can compute positions with a high accuracy anywhere on the globe using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be downloaded from the International GNSS Service (IGS) or obtained in real-time from a number of service providers, using either the Internet or satellite links.

By Inside GNSS

INS Face Off

TOP PHOTO: Antenna configurations on trials vehicle: Dual GPS antennas for the INS under test and single GPS antenna for the CIMU; BOTTOM PHOTO: Commercial IMU/DGPS system used for reference (left), FOG-based INS configuration (middle), and MEMS-based INS configuration 2 (right)

The automobile versus the horse and buggy. Cloud computing opposite desktop software. The trend is predictable, yet it is always surprising when one technology takes over the market space of another. After all, television did kill off the radio star.

By Inside GNSS

Drones to the Rescue!

August 1994, early morning. Spain’s Central Pyrenees Mountains still in darkness.

At the outset of an ascent to a 3,000-meter peak along the international border, one of the co-authors encounters a group of tourist hikers who have begun searching for a colleague who had left the camp the previous evening. In the pre-sunrise gloom, helicopters cannot yet operate.

A week later, the body of the hiker is found. The rescue efforts came, unfortunately, too late.

By Inside GNSS

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May 28, 2012

Figures 1, 2 & 3: Demystifying GLONASS Inter-Frequency Carrier Phase Biases

Return to main article: "Demystifying GLONASS Inter-Frequency Carrier Phase Biases"

By Inside GNSS

May 27, 2012

GNSS Hotspots | May 2012

One of 12 magnetograms recorded at Greenwich Observatory during the Great Geomagnetic Storm of 1859

1996 soccer game in the Midwest, (Rick Dikeman image)

Nouméa ground station after the flood

A pencil and a coffee cup show the size of NASA’s teeny tiny PhoneSat

Bonus Hotspot: Naro Tartaruga AUV

Pacific lamprey spawning (photo by Jeremy Monroe, Fresh Waters Illustrated)

“Return of the Bucentaurn to the Molo on Ascension Day”, by (Giovanni Antonio Canal) Canaletto

The U.S. Naval Observatory Alternate Master Clock at 2nd Space Operations Squadron, Schriever AFB in Colorado. This photo was taken in January, 2006 during the addition of a leap second. The USNO master clocks control GPS timing. They are accurate to within one second every 20 million years (Satellites are so picky! Humans, on the other hand, just want to know if we’re too late for lunch) USAF photo by A1C Jason Ridder.

Detail of Compass/ BeiDou2 system diagram

Hotspot 6: Beluga A300 600ST

1. GROWTH SPURT
California/Nevada, USA
√ The age of the Sierra Nevada mountains — home of Yosemite Valley and Lake Tahoe — is puzzling to geodesists. Integrating GPS and inSAR, Universities of Nevada and Glasgow teams studied the area’s uplift and found that it is growing by 1 to 2 millimeters per year. The verdict? The entire range could have arisen in less than 3 million years.

By Inside GNSS

Figure 3: How do GNSS-derived heights differ from other height systems?

Return to main article: "How do GNSS-derived heights differ from other height systems?"

By Inside GNSS

Multi-GNSS Integration

iNsight team members: (L to R) Zeynep Elmas and Terry Moore (Nottingham), Marek Ziebart (UCL), Mojtaba Bahrami (at that time of UCL), Carl Milner (then of Imperial), Alper Ucar (Westminster), Chris Hide (Nottingham), Shaojun Feng (Imperial), Ziyi Jiang (UCL) and Paul Groves (UCL). Not pictured, Washington Ochieng (Imperial) and Izzet Kale (Westminster).

The diversity and redundancy provided by multiple, independent, compatible, and in some respects, interoperable GNSS systems must be a good thing, right?

Well, almost certainly. But as with many things in life and technology, the devil’s in the details. And, as the varied characteristics and design specifications of new GNSSes and regional systems become clearer, it may not be too early to sort out those details.

By Inside GNSS

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IP Rights and Wrongs

As Desi Arnaz often said to Lucille Ball during an “I Love Lucy” episode on TV, “You’ve got some ’splaining to do.”

I refer, of course, to the untoward and unexpected initiative by the British Ministry of Defense (MoD) to patent the technical innovations that underlie the planned next generation of civil GNSS signals.

By Dee Ann Divis