Global Navigation Satellite Systems Engineering, Policy, and Design
The U.S. Coast Guard Navigation Center (NAVCEN) has issued an alert today (February 2, 2015) regarding problems with some brands and models of GPS receivers as the result of inclusion of information about a future leap second.
By Inside GNSS
Three threads of legislation running through the new congressional session —location privacy, critical infrastructure protection, and updates to the Communications Act — are worth careful monitoring by the GPS community. One bill in particular, the Terrorism Prevention and Critical Infrastructure Protection Act of 2015, could expand the definition of critical infrastructure to include the GPS system — something GNSS experts have been advocating for several years.
By Inside GNSS
After a delay to reformulate the system design, South Korea is moving ahead to implement a national enhanced Loran (eLoran) system to provide uninterrupted positioning, navigation, and timing (PNT) services in the wake of GPS jamming by North Korea.
By Inside GNSS
Galileo Sensor Stations (GSSs) pick up Galileo signals in space (SIS) to perform clock synchronisation and orbit measurements which are fed back to the twin Galileo Control Centres to serve as the basis of the navigation message incorporating clock and position corrections and associated integrity data. Uplink Stations (ULSs) then uplink this navigation message to the Galileo satellite navigation payloads for rebroadcast to users. Telemetry, Tracking and Command Stations (TT&Cs) provide the link between the Control Centres and the satellite platforms. ESA figureGalileo’s operation controllers will temporarily stop updating satellite orbital positions in the system’s navigation messages beginning near the end of this month in order to help implement upgrades in the ground mission segment, the European Space Agency (ESA) announced today (January 19, 2015).
Although the Galileo satellites will continue to transmit navigation signals, the generation and uplink of updated navigation messages will be interrupted during the last week of January for about five weeks.
By Inside GNSS
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. SLAVE TRADE
Bangkok, Thailand
These days getting the United States, Russia, China, and Europe to agree on a common policy seems to be an increasingly rare event.
That’s why the long-standing comity among system operators in the GNSS sphere is particularly notable and welcome. “Interoperable and compatible” is the first principle espoused by the four nations under the aegis of the International Committee on GNSS.
By Dee Ann Divis
ICM SMT 360 timing moduleTrimble has introduced a new portfolio of GNSS-based time and frequency products to address the synchronization needs of the fast-growing 4G LTE (Long Term Evolution) small-cell telecom market.
Mobile telecom networks, whether 3G, 4G LTE, LTE-Advanced (LTE-A) wireless technologies, or a combination, need high-precision synchronization and syntonization.
By Inside GNSS
In a nod to the usefulness of international enhanced Loran (eLoran) systems the U.S. Department OF Defense (DoD) in January began a search for companies able to supply some 50,000 eLoran receivers. Meanwhile a multi-agency team continues sketching out the structure of a potential U.S. eLoran system for federal officials weighing a relaunch of the program as a backup to GPS.
By Inside GNSS
The group that sets standards for aircraft navigation receivers is planning work on four new types of devices including the first multi-signal and multi-constellation aviation receivers and a more cost effective navigation system to help planes traverse GPS-impaired areas.
By Inside GNSS
A decade has passed since the first GNSS system-level authentication protocols were proposed, and yet the current ongoing discussion is still, “Do we really need GNSS signal authentication?” Indeed, the current argument is whether we need authentication at the system level (the satellite broadcast service) or whether user-based authentication (anti-spoofing) is sufficient for a number of application requirements.
By Inside GNSS
No reality show contestant ever neared the finish line without the producers serving up another challenge. And so it is for would-be multi-GNSS users in the United States.
After dodging budget cuts, thwarting other teams’ attempts to grab critical frequencies, and dealing with jamming and technical problems, members of the U.S. GNSS community were thrown another curve late last year when they learned that signals from GLONASS and other international constellations must be authorized for use in the United States.
By Dee Ann Divis
Running San Francisco Marathon, with daughter, Tanera. Note GPS watch.SIDEBAR: Frank van Diggelen’s Compass Points
“It all traces back to my parents,” says Frank van Diggelen. “My father, Tromp van Diggelen, was a surfer. He taught me to surf and swim, in that order, when I was five. I was racing sailboats before I was 10, and there’s a lot of navigation there. Even when you’re just on a lake, the racing is all about reading the wind, understanding angles of convergence, velocity-made-good, and so on.”
By Inside GNSS
College Hall at Cranwell, Lincolnshire, EnglandTerry Moore will speak about "What Next for GNSS" at the Royal Institute of Navigation Anderson Memorial Lecture at Whittle Hall, RAF Cranwell, Sleaford, Lincs, U.K. on March 2, 2015.
By Inside GNSS
