Columns and Editorials

January 19, 2012

GNSS Hotspots

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. ICE BREAKER
Nome, Alaska USA

√ Two 2 1/2 pound GPS-guided UAVs that tolerate extreme cold helped bring fuel to snowbound Nome, Alaska over two weeks in January. On daily photographic missions, the Aeryon Scouts helped University of Fairbanks researchers map ice thickness in the frozen harbor so a Coast Guard icebreaker could slowly guide a Russian fuel tanker close enough to pump the fuel to shore.

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By Inside GNSS

GPS – The DoD’s Profit Center

Why Washington continues to talk about deficits while the country is talking about jobs and foreclosures is kind of a mystery, but let’s play along.

Following the failure of Congress’s would-be budget-cutting committee that wasn’t so super, the Department of Defense is facing about $500 billion in mandatory cuts over the next 10 years.

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By Dee Ann Divis

Code Tracking and Pseudoranges

FIGURE 2: Pseudorange computation based on transmission. On the left side, the satellites are transmitting mes¬sages synchronously. On the right side, the four subframes are received asynchronously, due to the different propagation time. The TLM word is taken as a referene. The time differences ?i are computed on the basis of the relative arrival times of the front of the first bit of the TLM word.

Q: How can pseudorange measurements be generated from code tracking?

A: Every GNSS receiver processes the received signals to obtain an estimate of the propagation time of the signal from the satellites to the receiver. These propagation times are then expressed in meters to solve for the user position using trilateration.

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By Inside GNSS

New Austerity Squeezes GPS as DoD Tightens Its Belt

Embracing the need for debt-driven discipline, the White House has revised its strategy for the nation’s defense, taking a more fiscally constrained approach that reduces the number of troops and future spending on defense systems.

The new plan, formally announced January 5, was already being put into effect last summer. “The strategic guid­ance was the compass by which we steered the budget review leading to the president’s budget for fiscal year ‘13 and the years thereafter,” Deputy Secretary of Defense Ashton B. Carter told reporters.

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By Dee Ann Divis