The System: Galileo, Compass, GPS Launches All Succeed

November 1, 2012  - By
Image: GPS World

October 12: A Soyuz launcher carrying two Galileo In-Orbit Validation (IOV) satellites deployed its twins into orbit within 4 hours after take-off, at close to 23 200 km altitude. They join two earlier IOV spacecraft launched in October 2011. Once all four are operational in space, they will provide the minimum number of satellites required for navigational fixes — enabling system validation testing when all are visible in the sky.

The satellites were built by a consortium led by the Astrium division of EADS, which produced the platforms and has responsibility for the payloads, while Thales Alenia Space handled assembly and testing.

October 11: The L5 transmitter aboard GPS Block IIF-3 satellite SVN65/PRN24 was switched on, transmitting the civilian safety-of-life GPS signal, designed to meet demanding requirements for safety-of-life transportation and other high-performance applications.

A day earlier, SVN65 began transmitting L1 and L2 signals as PRN24 on October 8. A number of stations of the International GNSS Service are tracking the satellite. As of press date for this magazine (October 25) the satellite is included in broadcast almanacs although it is set unhealthy and will continue to be so until satellite commissioning is completed. The satellite is drifting towards its designated orbital position of Slot 1 in Plane A.

The launch of the GPS Block IIF-3 satellite took place as scheduled October 4, aboard a United Launch Alliance Delta IV rocket from Cape Canaveral, Florida.

October 1: The two BeiDou-2/Compass satellites launched on September 18 reached their circular medium-Earth orbits and started transmitting navigation signals. Several stations participating in the International GNSS Service’s Multi-GNSS Experiment as well as some in the Cooperative Network for GNSS Observation started tracking the satellites on September 26.

Meanwhile, China is in the final stage of preparations for Compass G6 (G2R) satellite launch, scheduled to occur on October 25 from Xichang Launch Center.

October 3: The Indian Space Research Organization announced that the orbit-raising maneuvers of GSAT-10 satellite have been successfully completed from ISRO’s Master Control Facility. The maneuvers placed  the GSAT-10, launched September 30, in an orbit with 35,000-kilometer high orbit, with an orbit period of 23 hours 50 minutes, and a designated location of 83 degree East. GSAT-10 contains a payload to support the Indian GPS and GEO Augmented Navigation (GAGAN) satellite-based augmentation system. The satellite will likely use PRN code 128.

Looking forward:

November 2: A Russian rocket  carrying a Luch data-relay satellite with a payload to service the the Russian satnav system is due to launch on this day, postponed from earlier dates in August and October. The second of a set of three geostationary satellites launched to reactivate Roscosmos’s Luch Multifunctional Space Relay System, it will also carry transponders for the System for Differential Correction and Monitoring (SDCM), Russia’s satellite-based augmentation system. The transponders will broadcast GNSS corrections on the standard GPS L1 frequency using C/A PRN codes assigned by DoD’s Global Positioning Systems Directorate. According to the most recent announcement, it will be positioned at 16 degrees West longitude, joining Luch-5A, already  in an orbital slot at 95 degrees East longitude.

Protecting GNSS Presentation at ION and INTERGEO

How to test receivers, how to monitor interference, and how to report interference formed the focus of “Protecting GNSS,” a presentation given at ION-GNSS in September and at the INTERGEO exhibition in Germany in October. GPS World hopes to present a video of the talk and its presentation slides at in the near future.

In his talk, CEO Javad Ashjaee of JAVAD GNSS discusses the differences between out-of-band interference (“easy to deal with”) and in-band interference (“more difficult to deal with”). For the latter case, he offers a 64th-order adaptive filter for narrow-band carrier-wave (CW) interference, known as J-Shield, that is incorporated in current JAVAD GNSS receivers, for example the Triumph-VS and Victor-VS. This feature implements, he states, embedded real-time monitoring at the touch of two buttons on the receiver.

Users can then view, in the radio-frequency analysis stage, five different aspects of interference detection and monitoring:
◾    Spectrum shape
◾    Average automatic gain control (AGC)
◾    AGC variations
◾    carrier-to-noise (C/N0) losses
◾    Real-time cycle slips.

In subsequent digital analysis, after digital processing of the signals, Ashjaee showed interference detected by the company’s receivers operating from its San Jose office (see slide, interference with L2) and Moscow office, regarding both GPS and GLONASS signals.

Reporting. TRIUMPH-VS and Victor-VS can send interference reports to FTP sites and authorized persons can view them via browsers (computers, iPhones, and so on). The receivers can also email reports to intended people.

Ashjaee advocated for GNSS receivers in all reference stations to have such interference monitoring and reporting features. In this way, users could monitor interference in their area before performing tasks, just as pilots check the weather before take-off.


China, Europe to Negotiate Spectrum

The European Union (EU) and China will reportedly meet in December in Paris to discuss overlapping radio frequencies both plan to use for their future encrypted government/military satellite navigation services.

The meeting will be conducted under what the Joint Statement on Space Technology Cooperation specifies as the ITU Framework. ITU is the International Telecommunication Union of Geneva, a United Nations affiliate that regulates satellite orbital slots and frequencies.

The statement was signed as an annex to a broader EU-China summit held September 20 in Brussels. The two sides continue collaboration on satellite navigation despite the signal conflict, which has been a subject of debate for at least two years.

The 27-nation EU and China have agreed to continue the China-Europe GNSS Technology Training and Cooperation Center.

Contract for 37 New GLONASS Birds

A federal target program, approved by the Russian Government, has provided measures to maintain and develop the GLONASS system. The Reshetnev Company from 2012 to 2020 will manufacture 15  GLONASS-M satellites and 22 GLONASS-K. The work in this direction is taking place at ISS at full speed. Now the company is making space apparatus GLONASS-M No. 50 (likely to be known as 750 once launched) and has signed contracts with related enterprises for the supply of equipment for a few more satellites in this series. ISS has already completed the manufacture of satellites GLONASS-M No. 47, No. 48, and No. 49. Routine tests confirmed compliance characteristics of the design and with operational documentation. The space vehicles have been put in the assembly shop for safekeeping. ISS has sent a next-generation navigation satellite GLONASS-K No. 12L to the spaceport. A decision on the launch date of the navigation satellites will be made by Roscosmos after an analysis of the state of the GLONASS constellation.

Leadership Awards, Directions 2013 Next Month

The following individuals received GPS World 2012 Leadership Awards in September in Nashville, Tennessee. The magazine’s Leadership Dinner and awards were sponsored by Lockheed Martin and Deimos Space.

Satellites: Martin Unwin, Surrey Satellite Technology Limited.  One of the driving forces behind the GIOVE-A satellite (recently retired) and the Galileo IOV satellites.

Signals: Todd Humphrey, Radionavigation Laboratory , University of Texas at Austin. Leader of several seminal studies on spoofing and jamming; testified this summer before Congress on the subject.

Services: Waldemar Kunysz, NextNav LLC. Work on WAPS (Widea Area Positioning System) design and implementation in the continental USA. He spent the previous 16 years with NovAtel on various research projects and novel antenna designs.

Products: Robert Lutwak, Symmetricom. Practical advances to overcome the intrinsic physical barriers to affordable chip-scale atomic clocks, enabling precision time and time transfer in mobile GNSS and communications systems.

Remarks by the award winners on the future of GNSS will appear as Directions 2013 in December issue.



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