Aerospace and Defense

Code Tracking and Pseudoranges

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

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
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USAF Awards Lockheed Additional GPS IIIA Satellite Buy
January 12, 2012

USAF Awards Lockheed Additional GPS IIIA Satellite Buy

The U.S. Air Force has awarded Lockheed Martin a $238 million contract for production of the third and fourth satellites in the next-generation GPS constellation, known as GPS III.  The acquisition of the next two GPS IIIA satellites at one time will allow the Lockheed Martin-led team to maximize efficiencies in satellite manufacturing.

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By Inside GNSS
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GNSS Hotspots | November 2011
November 21, 2011

GNSS Hotspots | November 2011

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. Portland, Oregon and Los Angeles, California USA
TWINS!

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By Inside GNSS
Oh No! Not LightSquared Again!
November 16, 2011

Oh No! Not LightSquared Again!

Please.

Please. Please. Please. 

Can we please talk about something besides LightSquared?

Not yet? You mean, they are still here?

And we have so many other GNSS-related topics that deserve comment: 

Some peculiar cuts in civil GPS funds and GPS III budgets being proposed by congressional committees. 

A re-examination — aka analysis of alternatives — of GPS and PNT options in general. Space weather and an impending solar max. Warrantless GPS-aided tracking before the Supreme Court.

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By Inside GNSS
GNSS Systems Reports: Compass ICD, Expanded QZSS, GLONASS Launches, GPS Budget Issues, Galileo Reprofiling
October 4, 2011

GNSS Systems Reports: Compass ICD, Expanded QZSS, GLONASS Launches, GPS Budget Issues, Galileo Reprofiling

[Updated October 3] All five of the world’s major satellite navigation systems are poised to offer new capability — if the money comes through — program representatives told attendees at the recent Institute of Navigation’s GNSS 2011 conference in Portland.

The satellite navigation systems in China, Japan, and the United States have each recently had new satellites added, while those in Russia and Europe are poised for new launches. Budgets are in flux for most systems, however, so it remains to be seen how the systems will advance over the next year.

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By Inside GNSS
TRANM
September 18, 2011

TRANM

» Return to ESNC page

The following is one of the five top submissions to the 2011 USA Challenge. The North American regional contest in the European Satellite Navigation Competition(ESNC) is a global search for the newest, best and most innovative GNSS application ideas with €20,000 in prize money for the international winner, the 2011 Galileo Master.

TRANM

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By Inside GNSS
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