GNSS & the Law

October 1, 2010

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. GARMIN RECALL
Olathe, Kansas USA

√ In late August, Kansas-based GPS consumer manufacturer Garmin International Inc. recalled 1.25 million Nuvi GPS units whose batteries can overheat and catch fire. In September, Nissan and Suzuki recalled Nuvi units in their vehicles. Check the special recall website to see if you are affected.

Read More >

By Inside GNSS

Launch Fever

It is not all about the satellites, of course.

And, despite the thrill of launches — the Fourth of July and every other national holiday celebration all grown up — it’s not about the rockets.

When evaluating the progress of GNSS programs, however, satellites and launches are a way to keep count — in fact, it is the way most of us do keep count.

By that measure, then, the numbers are adding up quickly.

Read More >

By Inside GNSS
September 15, 2010

A Search for Spectrum: GNSS Signals in S-Band, Part II

GNSS utilization of the S-band portion of the radio spectrum provides some challenges to designers of both GNSS navigation signals as well as signals used by other services, in terms of interference avoidance and signal power.

An important existing user of S-band spectrum is the Globalstar communications satellite system. The voice and data services provided by Globalstar employ the 2483.5–2500 MHz band for its satellite downlink communications to user terminals. Additionally, these satellites use multi-beam antennas to enable frequency reuse.

Read More >

By Inside GNSS
August 27, 2010

The Missing ICD

Successful launch of three Compass (Beidou-2) satellites so far this year and reports of another two planned later in 2010 have elevated awareness of China’s accelerating GNSS program.

Added to the two spacecraft placed in orbit in 2007 and 2009, that would bring the modernized Beidou constellation up to seven — halfway to the 13 or 14 satellites planned for the regional system scheduled to be available by 2012.

Read More >

By Inside GNSS
August 26, 2010

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. WHO WON?
Portland, Oregon and Munich, Germany
√ Judges all over the world are poring over 357 GNSS app innovations submitted to the 2010 European Satellite Navigation Contest from Europe, Australia, the Middle East, Taiwan and North America.  Inside GNSS’s USA Challenge will announce our five finalists at ION GNSS 2010 in Portland, Oregon. The winners will celebrate on October 18 in Munich.

Read More >

By Inside GNSS
August 17, 2010

A Search for Spectrum

FIGURE 1: Example of accuracy close to one centimeter provided by the integer ambiguity resolution on undifferenced phase (IARUP) technique using GPS L1 and L2 signals

In recent years, researchers have explored possible new allocations for Radio Determination Satellite Service (RDSS) and Radio Navigation Satellite Service (RNSS) spectrum from a regulatory point of view. These studies have mainly discussed S-band and C-band in addition to L-band.

The International Telecommunications Union (ITU) Radio Regulations define RNSS as a subset of RDSS. Although the allocations are differentiated — RDSS usually has a paired uplink — both can actually be used for satellite navigation.

Read More >

By Inside GNSS

A Fully Digital Model for Kalman Filters

Q: Is it possible to define a fully digital state model for Kalman filtering?

A: The Kalman filter is a mathematical method, purpose of which is to process noisy measurements in order to obtain an estimate of some relevant parameters of a system. It represents a valuable tool in the GNSS area, with some of its main applications related to the computation of the user position/velocity/time (PVT) solution and to the integration of GNSS receivers with an inertial navigation system (INS) or other sensors.

Read More >

By Inside GNSS
July 23, 2010

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. EARTHQUAKE!
Seattle, Washington USA
√ Want to know where an earthquake will occur and how big it will be? The Pacific Northwest Geodetic Array (PANGA) geodesy lab can tell you. They use 350 continuously operating high-precision GPS receivers and can analyze and share quake data in less than a minute. (Fact: A megaquake is likely 50 miles from Seattle).

PANGA’s website

Read More >

By Inside GNSS
July 21, 2010

Interesting. Too Interesting?

In the world of GNSS we usually think of more as better. More systems, more satellites, more signals — all contribute to greater availability of robust positioning, navigation, and timing.

Certainly that was the mood at the June meeting of the Asia-Pacific Economic Cooperation — GNSS Implementation Team (APEC-GIT) in Seattle, Washington.

Read More >

By Inside GNSS
June 22, 2010

Generating Carrier Phase Measurements

Q: What is the carrier phase measurement? How is it generated in GNSS receivers?

A: Simply put, the carrier phase measurement is a measure of the range between a satellite and receiver expressed in units of cycles of the carrier frequency. This measurement can be made with very high precision (of the order of millimeters), but the whole number of cycles between satellite and receiver is not measurable.

Read More >

By Inside GNSS