satellites/space segment Archives - Page 17 of 23 - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

satellites/space segment

Air Force Secures ITU Filing with GPS L5 Signal Transmission
April 10, 2009

Air Force Secures ITU Filing with GPS L5 Signal Transmission

Time Series and Power Spectrum of the L5 Demonstration Signal

The GPS IIR-20(M) satellite successfully transmitted for the first time a GPS signal in the L5 frequency band today (April 10), according to the U.S. Air Force operators of the Global Positioning System. L5, the third civil GPS signal, will eventually support safety-of-life applications for aviation and provide improved availability and accuracy to users.

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By Inside GNSS
GPS L5 Signal Goes on the Air April 10
April 9, 2009

GPS L5 Signal Goes on the Air April 10

Stanford “Big Dish” Antenna

U.S. Air Force officials are moving quickly to turn on the new civil GPS L5 signal after lengthy delays due to technical problems had brought the program close to an International Telecommunications Union (ITU) deadline for transmitting on the frequency.

The Air Force plans to begin transmitting the signal at 5 a.m. (PDT) on April 10 using the Block II R-20(M) satellite launched March 24. An L5 signal demonstration is planned the same day, organized by the GPS Wing and SRI International. The L5 spectrum will be received and plotted at the SRI’s 150-foot “big dish” antenna facility in the hills over looking Stanford University, California.

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By Inside GNSS
SSTL Leads Team Developing GNSS-Based Remote Sensing of Sea State
March 24, 2009

SSTL Leads Team Developing GNSS-Based Remote Sensing of Sea State

Sea State Monitoring

Surrey Satellite Technology Limited (SSTL) will lead a British project to exploit signals from GPS and other GNSS satellites that are reflected from the Earth for remote sensing purposes.

The project will investigate a prototype instrument capable of measuring the roughness of the sea and soil moisture content, providing data for atmospheric science and for operational ocean and weather forecasting.

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By Inside GNSS
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GPS Satellite with L5 Payload Launches Successfully

GPS Satellite with L5 Payload Launches Successfully

Block IIR-20(M) launch from Cape Canaveral. Photo by Carleton Bailie, United Launch Alliance.

GPS program managers and users — especially the U.S. civil aviation community — can breathe a sign of relief following the successful launch Tuesday (March 24) of a satellite carrying a demonstration payload of the new L5 signal.

Built by the Lockheed Martin Company, the modernized Block II replenishment spacecraft, GPS IIR-20(M), is moving toward plane B, slot 2 to replace space vehicle number (SVN) 30. If all goes well, U.S. Air Force controllers expect to set the satellite healthy for navigation users worldwide next month.

Among other signals and capabilities, the IIR-20(M) will be the first to transmit the new GPS civil signal centered on 1176.45MHz (±12 MHz) within the protected aeronautical radionavigation service (ARNS) band. This so-called L5 signal will provide a second safety-of-life signal that meets the technical requirements for enabling aircraft to make precision landings in high multipath environments.

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By Inside GNSS
More Problems with GPS IIF; IIR-(20)M Is L5’s Plan B
March 18, 2009

More Problems with GPS IIF; IIR-(20)M Is L5’s Plan B

Just when you thought it was safe to go back in the water . . .

Discovery of a power anomaly in signal generator of the first GPS Block IIF space vehicle (SV) has thrown a new wrinkle into the long-delayed follow-on generation of spacecraft.

Meanwhile, it’s all systems go (and all fingers crossed) for launch of a modernized Block IIR satellite IIR-20(M) with the demonstration L5 navigation payload designed to secure priority GPS access to the frequency.

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By Inside GNSS
Munich Summit Highlights Satellite Navigation Plans, GNSS Program Struggles
March 6, 2009

Munich Summit Highlights Satellite Navigation Plans, GNSS Program Struggles

Paul Verhoef, European Commission (left), and Yin Jun, China Ministry of Science and Technology


Highlights of the 2009 Munich Satellite Navigation Summit (March 3- 5): Russia will place its first CDMA signal on the GLONASS L3 frequency that overlaps the European Galileo E5b spectrum; China plans to launch three Compass satellites this year and seven more next year to provide a regional capability for Compass/Beidou, followed by completion of the full 30-MEO, 5-GEO constellation after 2015 and before 2020; Galileo program discussions revealed tensions around negotiations with China about a frequency overlay of Compass signals on the security-oriented Public Regulated Service as well as the question of whether the costs to build Galileo can be kept within the €3.4-billion limit agreed by the European Council and the European Parliament; the GPS Block IIR-20(M) satellite with an L5 demonstration payload will be launched later this month in what may be the program’s last chance to secure primary GPS access to the frequency.

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By Inside GNSS
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Satellite Collision Raises Issue of Similar GNSS Risks
February 13, 2009

Satellite Collision Raises Issue of Similar GNSS Risks

GPS Orbital Decay. Aerospace Corporation

The February 10 collision of an active Iridium satellite and a defunct Russian military communications satellite underlines a concern raised recently at the International Committee on GNSS (ICG) about the need to include coordination of space vehicle (SV) operations.

In comments during a session of Working Group A (compatibility and interoperability) during the ICG’s recent meeting in Pasadena, California, Professor Grigory Stupak of the Russian Institute for Space Device Engineering (RISDE), noted that Russia’s “position is that compatibility includes more than just signals,” among other things, “the sharing of orbits and disposal of satellites.”

Similar concerns have been expressed in recent years by organizations that have studied the possibility of GNSS satellites, particularly those that have been “parked” in disposal or graveyard orbits, to drift and possibly collide with one another.

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By Glen Gibbons
New Russian GLONASS Satellites in Operation

New Russian GLONASS Satellites in Operation

The last of three GLONASS satellites launched December 25 began broadcasting a healthy navigation signal today (February 12), according to the Russian Space Agency’s Information-Analytical Center, bringing Russia’s operational GNSS constellation to 20 spacecraft.

One satellite, space vehicle number (SVN) 701 launched more than five years ago, has been off-line and in “maintenance” status for the last month. Another spacecraft, SVN 722, is transmitting only in the GLONASS L1 band.

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By Glen Gibbons
Russia Launches Three More GLONASS-M Space Vehicles
December 26, 2008

Russia Launches Three More GLONASS-M Space Vehicles

Proton with three GLONASS-Ms

The Russian Federal Space Agency (Roscosmos) successfully launched a Proton-M rocket and three GLONASS-M satellites at 10:53 a.m. (GMT) on December 25 from the Baikonur spaceport in Kazakhstan.

The spacecraft were placed into orbital plane 1 on the GLONASS constellation, where they will occupy slots 2, 3, and 8, according to the Roscosmos Information-Analytical Center.

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By Glen Gibbons
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