200601 January/February 2006 Archives - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

Russia Launches GLONASS Trio

Inside GNSS — Mon, 02 Jan 2006 06:11:47 +0000

Russia gave a Christmas gift to the GNSS world with its launch of three GLONASS satellites, including two modernized GLONASS-M spacecraft, on December 25 2005.

Russia gave a Christmas gift to the GNSS world with its launch of three GLONASS satellites, including two modernized GLONASS-M spacecraft, on December 25 2005.

The spacecraft (Cosmos 798, 713, and 714) will be placed into slots 19, 24, and 23, respectively, of orbital plane 3. Cosmos 793, currently on orbit, will be moved from slot 23 into slot 20.

The launch brings the number of operational GLONASS satellites to 16 and fills out the first and third orbital planes. The second orbital plane remains without satellites.

Four GLONASS-M are now in place with the capability of broadcasting a second civil signal in the L2 band. See more details about recent developments and plans for the GLONASS system in the article, “GLONASS: The Once and Future GNSS” In the January-February 2006 Inside GNSS magazine.

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New EC DG-TREN Director-General

Inside GNSS — Mon, 02 Jan 2006 06:09:23 +0000

Matthias Ruete has been named as director-general of the European Commission’s Directorate- General for Energy and Transport (EC DG-TREN), which has overall responsibility for implementation of the Galileo program on behalf of the European Union (EU). He replaces François Lamoreaux.

Ruete is very familiar with the Galileo program, having served as director of DG-TREN’s international relations, trans-European transport and infrastructure networks directorate from 1998-2000, which oversaw development of Europe’s GNSS program during its middle years.

From 2001 to 2004 he was a director in the EC’s Directorate-General for Enlargement, involved with negotiations and preparations for nations entering or applying to become members of the EU.

Last year he was a director with the DG for Enterprise and Industry directorate responsible for coordination of competitiveness.

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GPS L2C is on the air

Inside GNSS — Mon, 02 Jan 2006 05:56:17 +0000

Civil GPS users now have a second full signal available to them — albeit on only one satellite and “at the user’s own risk” — courtesy of the first modernized Block IIR (IIR- 14M) spacecraft launched last September. And the world’s geodetic community is already moving to take advantage of it with announcement of an addendum to the receiver autonomous exchange (RINEX) format used to combine high-precision position data from different types of GPS receivers.

The GPS Operations Center at Schriever Air Force Base announced availability of the L2C in a December 16 Notice Advisory to Navstar Users (NANU). The signal is transmitted at the GPS L2 frequency centered at 1227.60 MHz. Satellite IIR-14M, placed into the orbital plane/slot C4, is also known by its space vehicle and pseudorandom noise code numbers: SVN53/PRN17.

Military users will have additional access to two versions of the new military M-code, one at L2 and the other at L1 (centered at 1575.42 MHz).

Meanwhile, on January 11 Prof. Dr. Werner Gurtner, head of the satellite laser ranging department at the Astronomical Institute of the University of Berne, Switzerland, announced definition of a new C2 code in the RINEX format widely used by geodesists and incorporated by manufacturers into numerous high-precision GPS receivers. Gurtner is one of the originators of the RINEX format introduced more than 16 years ago.

The definition is included in Version 2.11 of the format, which also includes clarifications to the RINEX geostationary satellite-based augmentation (SBAS GEO) Navigation Message file.

These introduce four new observables into the Met Data Files (wind speed and direction, rain, and hail indicator) and define codes for the Galileo System (E), Galileo System Time (GAL) and frequency numbers for the various Galileo frequency bands, L5 for GPS, and SBAS.

Version 2.11 also contains file names for high-rate tracking data recommended by the International GNSS Service (IGS). Documentation is available at the IGS ftp server .

In its Dec. 16 NANU, the U.S. Air Force emphasized that it would not guarantee the availability or quality of L2C signals until initial operational capability (IOC) — or the broadcast of the signal on at least 21 satellites.

Moreover, the Air Force cautioned users that the new signal is under development and may be used for a variety of test applications prior to IOC. Consequently, until that time availability and quality of the L2C signal may be subject to change without prior notice. “Therefore,” the NANU concludes, “any use of the L2C signal prior to being declared operational is at the user’s own risk.”

Some GPS manufacturers have already begun producing receivers capable of processing the L2C signal. Among these are the Trimble R7 and R8 receivers, Septentrio’s PolaRx2C, NovAtel’s OEMV family, the Topcon Paradign G3 chipset and equivalent Javad Navigation Systems GeNiuSS chip. In addition to these varieties of user equipment, Spirent Communications’ GSS7700 hardware simulation system can also generate L2C signals.

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First Galileo Satellite Begins Broadcasts

Inside GNSS — Mon, 02 Jan 2006 05:53:37 +0000

European Space Agency (ESA) and Surrey Satellite Technology Ltd.(SSTL) operators have completed the on-orbit preparations and activated the navigation payload for GIOVE-A, the first Galileo satellite launched December 28.

Galileo RF transmissions began January 12, and ESA and SSTL operators have successfully received and decoded the payload signals.

GIOVE A was placed in orbit at an altitude of 23,260 kilometers by a Russian Soyuz-Fregat rocket operated by Starsem that lifted off from the Baikonur cosmodrome in Kazakhstan.

The 600-kilogram satellite, built for ESA in just 30 months and for €28 million by SSTL of Guildford, United Kingdom, has three primary objectives: securing use of the frequencies allocated by the International Telecommunications Union (ITU) for the Galileo system, demonstrating critical technologies for the navigation payload of future operational Galileo satellites, and assessing the radiation environment of the orbits planned for the Galileo constellation.

GIOVE A will transmit in the frequencies allocated to Galileo: E2, L1, E1, E5, and E6. Evaluation of the signals is being made through the Chilbolton Observatory Facilities for Atmospheric and Radio Research in the UK and ESA’s station in Redu, Belgium.

A Galileo Experimental Test Receiver developed by Belgian GNSS company Septentrio Satellite Navigation NV is one of the receivers that is being used to verify the acquisition, tracking, and noise characteristics of all transmitted signals.

Formerly known as GSTB-V2/A, the GIOVE A satellite is carrying two redundant, small-size rubidium atomic clocks built by Temex Neuchatel Time (Switzerland), each with a stability of 10 nanoseconds per day, and two signal generation units — one built by SSTL capable of generating a simple Galileo signal and the other built by Alcatel Alenia Space (Italy) that provides a more representative Galileo signal.

The signals are broadcast through an L-band phased-array antenna designed to cover all of the visible Earth under the satellite. Two additional instruments monitor the types of radiation to which the satellite is exposed during its two-year mission.

The various Galileo signal modes will now be generated sequentially using the various GIOVE A payload chains. Payload commissioning activities should be completed by mid-February.

Additional measurement campaigns will then be carried out to assess the medium earth orbit radiation environment, characterize the performance of the on-board clocks, and perform signal-in-space experimentation.

A second, larger and more advanced demonstrator satellite, GIOVE B built by the Galileo Industries consortium, will be launched later this year in the spring. (An American news outlet reported an April 14 launch, but an ESA official said that it was too early to confirm a specific date, which would depend on the performance of GIOVE A.)

In addition to a rubidium clock, GIOVE B will carry a passive hydrogen maser (PHM), an extremely accurate clock that has been developed under ESA contract. The PHM will be the first of its kind to be flown in space and have its performance tested in a realistic environment.

GIOVE A is broadcasting an experimental signal through two separate channels at a time. GIOVE B will transmit signals through three separate channels.

ITU rules require that, once a satellite is transmitting, transmissions cannot be interrupted for more than four months. For this reason, the GIOVE B satellite will provide a back-up system once launched to ensure that these crucial frequencies are secured, according to SSTL.

After the two GIOVE spacecraft are checked out, four operational satellites built by Galileo Industries will be launched by 2008 to validate the basic Galileo space and related ground segments.

Once this in orbit validation (IOV) phase is completed, the remaining satellites will be launched to achieve full operational capability by 2010. ESA signed a contract with Galileo Industries on January 19 to provide continuing management and technical services during the IOV phase.

For its Galileo role beyond the IOV phase, ESA is currently preparing what is called “Galileo evolution” related to the next generation of the system,” says Dominique Detain, communications manager for ESA’s navigation department.

The December 28 launch represents the culmination of a process to develop a European GNSS that began more than a decade ago.

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