Global Navigation Satellite Systems Engineering, Policy, and Design
Experts at the German Aerospace Center (DLR) are analyzing signals from Japan’s first quasi-zenith satellite, Michibiki, which began transmissions (including the first transmission from space of the new civil signal, L1C) on October 26, according to the Japan Aerospace Exploration Agency (JAXA).
By Inside GNSS
Catamaran Hotel, San DiegoThe Institute of Navigation International Technical Meeting (ITM) will take place January 24-26 at the Catamaran Hotel on Mission Bay in San Diego California.
Paul Kline of Honeywell Aerospace is the general chair. Jade Morton of Miami University, Ohio, is the program chair.
"Robotics Navigation" is the plenary session topic. Invited speakers will discuss current trends and future technologies that support navigation for surveillance, search and rescue, undergound and underwater robotics and unmanned air vehicles.
By Inside GNSS
FIGURE 1: Screenshot of RF simulation software showing GPS + GLONASS + Galileo constellationsIn the first article in this series (Inside GNSS, July/August, 2010) we looked at the range of tasks that require GNSS signal simulation during design, manufacturing, certification, and maintenance of GNSS equipment. The second installment (Inside GNSS, September, 2010) described a range of simulation solutions.
In this final article, we try to find a simulation solution that best suits a particular task.
By Inside GNSS
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.
By Inside GNSS
High-precision users of GNSS are used to solving for carrier phase integer ambiguities, but the recent publication of a GPS technical document has fixed a different kind of phase ambiguity — a linguistic one
By Inside GNSS
Artist’s rendering of GPS III satellite. Lockheed Martin imageMore than two years into a multi-billion-dollar contract, the Lockheed Martin team developing the U.S. Air Force’s next-generation GPS Block III satellites continues to defy the physics of large aerospace programs by successfully completing the program’s Critical Design Review (CDR) phase last week — two months ahead of the baseline schedule.
By Inside GNSS
The GPS Wing has authorized publication of three technical documents with updated specifications for the U.S. Global Positioning System, including the next-generation GPS Block IIIA satellites now in development, the L5 radio link, and the new L1 civil signal (L1C) that will be available with the GPS III spacecraft.
By Inside GNSS
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.
By Inside GNSS
FIGURE 1: Geographical overview of the 170 IGS stations tracking SVN62/PRN25 during its current 90-day checkout period. The blue curve illustrates the ground track of the spacecraft on August 9, 2010.For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
On May 27, 2010, the U.S. Air Force successfully launched the first satellite of the Block II “follow-on” (Block IIF) series, the fourth generation of GPS spacecraft that features more precise and powerful signals, an extended design life, and several other technical advances.
By Inside GNSS
GPS IIF satellite on Boeing assembly lineThe first GPS IIF satellite (SVN62/PRN25) is on orbit and doing well, despite some well-publicized speculation about higher-the-expected range residuals detected by researchers at the German Aerospace Center (DLR).
By Inside GNSS
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.
By Inside GNSS
GPS IIF-SV1 launch. United Launch Alliance photo[Updated July 22, 2010] Air Force officials at the GPS Wing have confirmed that higher-the-expected range residuals detected by researchers at the German Aerospace Center (DLR) are appearing in signals transmitted by the first GPS IIF satellite, designated SVN/62/PRN25.
But the Air Force and Boeing Space and Intelligence Systems, which built the spacecraft, point out SVN62 is currently performing within specifications, and the signal phenomenon does not appear likely to have any significant effect on GPS positioning when the satellite is declared operational.
By Inside GNSS
Space weather and aviation (NASA image)EUROCONTROL, Europe’s air traffic control agency, is studying the effect of solar events on civil aviation applications and developing ways to maintain air safety when GNSS signals are affected.
By Inside GNSS
